# Source code for sqlobject.main

    """
    SQLObject
    ---------

    :author: Ian Bicking <ianb@colorstudy.com>

    SQLObject is a object-relational mapper.  See SQLObject.html or
    SQLObject.rst for more.

    With the help by Oleg Broytman and many other contributors.
    See Authors.rst.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as
    published by the Free Software Foundation; either version 2.1 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
    USA.
    """
    import sys
    import threading
    import weakref
    import types
    import warnings
    from . import sqlbuilder
    from . import dbconnection
    from . import col
    from . import styles
    from . import joins
    from . import index
    from . import classregistry
    from . import declarative
    from . import events
    from .sresults import SelectResults
    from .util.threadinglocal import local
    from sqlobject.compat import PY2, with_metaclass, string_type, unicode_type

    if ((sys.version_info[0] == 2) and (sys.version_info[:2] < (2, 6))) or \
       ((sys.version_info[0] == 3) and (sys.version_info[:2] < (3, 4))):
        raise ImportError("SQLObject requires Python 2.6, 2.7 or 3.4+")

    if not PY2:
        # alias for python 3 compatability
        long = int

    """
    This thread-local storage is needed for RowCreatedSignals. It gathers
    code-blocks to execute _after_ the whole hierachy of inherited SQLObjects
    is created. See SQLObject._create
    """

    NoDefault = sqlbuilder.NoDefault

    class SQLObjectNotFound(LookupError):
        pass

    class SQLObjectIntegrityError(Exception):
        pass

    def makeProperties(obj):
        """
        This function takes a dictionary of methods and finds
        methods named like:
        * _get_attr
        * _set_attr
        * _del_attr
        * _doc_attr
        Except for _doc_attr, these should be methods.  It
        then creates properties from these methods, like
        property(_get_attr, _set_attr, _del_attr, _doc_attr).
        Missing methods are okay.
        """

        if isinstance(obj, dict):
            def setFunc(var, value):
                obj[var] = value
            d = obj
        else:
            def setFunc(var, value):
                setattr(obj, var, value)
            d = obj.__dict__

        props = {}
        for var, value in d.items():
            if var.startswith('_set_'):
                props.setdefault(var[5:], {})['set'] = value
            elif var.startswith('_get_'):
                props.setdefault(var[5:], {})['get'] = value
            elif var.startswith('_del_'):
                props.setdefault(var[5:], {})['del'] = value
            elif var.startswith('_doc_'):
                props.setdefault(var[5:], {})['doc'] = value
        for var, setters in props.items():
            if len(setters) == 1 and 'doc' in setters:
                continue
            if var in d:
                if isinstance(d[var], (types.MethodType, types.FunctionType)):
                    warnings.warn(
                        "I tried to set the property %r, but it was "
                        "already set, as a method (%r).  Methods have "
                        "significantly different semantics than properties, "
                        "and this may be a sign of a bug in your code."
                        % (var, d[var]))
                continue
            setFunc(var,
                    property(setters.get('get'), setters.get('set'),
                             setters.get('del'), setters.get('doc')))

    def unmakeProperties(obj):
        if isinstance(obj, dict):
            def delFunc(obj, var):
                del obj[var]
            d = obj
        else:
            delFunc = delattr
            d = obj.__dict__

        for var, value in list(d.items()):
            if isinstance(value, property):
                for prop in [value.fget, value.fset, value.fdel]:
                    if prop and prop.__name__ not in d:
                        delFunc(obj, var)
                        break

    def findDependencies(name, registry=None):
        depends = []
        for klass in classregistry.registry(registry).allClasses():
            if findDependantColumns(name, klass):
                depends.append(klass)
            else:
                for join in klass.sqlmeta.joins:
                    if isinstance(join, joins.SORelatedJoin) and \
                            join.otherClassName == name:
                        depends.append(klass)
                        break
        return depends

    def findDependantColumns(name, klass):
        depends = []
        for _col in klass.sqlmeta.columnList:
            if _col.foreignKey == name and _col.cascade is not None:
                depends.append(_col)
        return depends

    def _collectAttributes(cls, new_attrs, look_for_class):
        """Finds all attributes in `new_attrs` that are instances of
        `look_for_class`. The ``.name`` attribute is set for any matching objects.
        Returns them as a list.

        """
        result = []
        for attr, value in new_attrs.items():
            if isinstance(value, look_for_class):
                value.name = attr
                delattr(cls, attr)
                result.append(value)
        return result

    class CreateNewSQLObject:
        """
        Dummy singleton to use in place of an ID, to signal we want
        a new object.
        """
        pass

    class sqlmeta(with_metaclass(declarative.DeclarativeMeta, object)):
        """
        This object is the object we use to keep track of all sorts of
        information.  Subclasses are made for each SQLObject subclass
        (dynamically if necessary), and instances are created to go
        alongside every SQLObject instance.
        """

        table = None
        idName = None
        idSequence = None
        # This function is used to coerce IDs into the proper format,
        # so you should replace it with str, or another function, if you
        # aren't using integer IDs
        idType = int
        style = None
        lazyUpdate = False
        defaultOrder = None
        cacheValues = True
        registry = None
        fromDatabase = False
        # Default is false, but we set it to true for the *instance*
        # when necessary: (bad clever? maybe)
        expired = False

        # This is a mapping from column names to SOCol (or subclass)
        # instances:
        columns = {}
        columnList = []

        # This is a mapping from column names to Col (or subclass)
        # instances; these objects don't have the logic that the SOCol
        # objects do, and are not attached to this class closely.
        columnDefinitions = {}

        # These are lists of the join and index objects:
        indexes = []
        indexDefinitions = []
        joins = []
        joinDefinitions = []

        # These attributes shouldn't be shared with superclasses:
        _unshared_attributes = ['table', 'columns', 'childName']

        # These are internal bookkeeping attributes; the class-level
        # definition is a default for the instances, instances will
        # reset these values.

        # When an object is being created, it has an instance
        # variable _creating, which is true.  This way all the
        # setters can be captured until the object is complete,
        # and then the row is inserted into the database.  Once
        # that happens, _creating is deleted from the instance,
        # and only the class variable (which is always false) is
        # left.
        _creating = False
        _obsolete = False
        # Sometimes an intance is attached to a connection, not
        # globally available.  In that case, self.sqlmeta._perConnection
        # will be true.  It's false by default:
        _perConnection = False

        # Inheritance definitions:
        parentClass = None  # A reference to the parent class
        childClasses = {}  # References to child classes, keyed by childName
        childName = None  # Class name for inheritance child object creation

        # Does the row require syncing?
        dirty = False

        # Default encoding for UnicodeCol's
        dbEncoding = None

        def __classinit__(cls, new_attrs):
            for attr in cls._unshared_attributes:
                if attr not in new_attrs:
                    setattr(cls, attr, None)
            declarative.setup_attributes(cls, new_attrs)

        def __init__(self, instance):
            self.instance = weakref.proxy(instance)

        @classmethod
        def send(cls, signal, *args, **kw):
            events.send(signal, cls.soClass, *args, **kw)

        @classmethod
        def setClass(cls, soClass):
            cls.soClass = soClass
            if not cls.style:
                cls.style = styles.defaultStyle
                try:
                    if cls.soClass._connection and cls.soClass._connection.style:
                        cls.style = cls.soClass._connection.style
                except AttributeError:
                    pass
            if cls.table is None:
                cls.table = cls.style.pythonClassToDBTable(cls.soClass.__name__)
            if cls.idName is None:
                cls.idName = cls.style.idForTable(cls.table)

            # plainSetters are columns that haven't been overridden by the
            # user, so we can contact the database directly to set them.
            # Note that these can't set these in the SQLObject class
            # itself, because they specific to this subclass of SQLObject,
            # and cannot be shared among classes.
            cls._plainSetters = {}
            cls._plainGetters = {}
            cls._plainForeignSetters = {}
            cls._plainForeignGetters = {}
            cls._plainJoinGetters = {}
            cls._plainJoinAdders = {}
            cls._plainJoinRemovers = {}

            # This is a dictionary of columnName: columnObject
            # None of these objects can be shared with superclasses
            cls.columns = {}
            cls.columnList = []
            # These, however, can be shared:
            cls.columnDefinitions = cls.columnDefinitions.copy()
            cls.indexes = []
            cls.indexDefinitions = cls.indexDefinitions[:]
            cls.joins = []
            cls.joinDefinitions = cls.joinDefinitions[:]

        ############################################################
        # Adding special values, like columns and indexes
        ############################################################

        ########################################
        # Column handling
        ########################################

        @classmethod
        def addColumn(cls, columnDef, changeSchema=False, connection=None):
            post_funcs = []
            cls.send(events.AddColumnSignal, cls.soClass, connection,
                     columnDef.name, columnDef, changeSchema, post_funcs)
            sqlmeta = cls
            soClass = cls.soClass
            del cls
            column = columnDef.withClass(soClass)
            name = column.name
            assert name != 'id', (
                "The 'id' column is implicit, and should not be defined as "
                "a column")
            assert name not in sqlmeta.columns, (
                "The class %s.%s already has a column %r (%r), you cannot "
                "add the column %r"
                % (soClass.__module__, soClass.__name__, name,
                   sqlmeta.columnDefinitions[name], columnDef))
            # Collect columns from the parent classes to test
            # if the column is not in a parent class
            parent_columns = []
            for base in soClass.__bases__:
                if hasattr(base, "sqlmeta"):
                    parent_columns.extend(base.sqlmeta.columns.keys())
            if hasattr(soClass, name):
                assert (name in parent_columns) or (name == "childName"), (
                    "The class %s.%s already has a variable or method %r, "
                    "you cannot add the column %r" % (
                        soClass.__module__, soClass.__name__, name, name))
            sqlmeta.columnDefinitions[name] = columnDef
            sqlmeta.columns[name] = column
            # A stable-ordered version of the list...
            sqlmeta.columnList.append(column)

            ###################################################
            # Create the getter function(s).  We'll start by
            # creating functions like _SO_get_columnName,
            # then if there's no function named _get_columnName
            # we'll alias that to _SO_get_columnName.  This
            # allows a sort of super call, even though there's
            # no superclass that defines the database access.
            if sqlmeta.cacheValues:
                # We create a method here, which is just a function
                # that takes "self" as the first argument.
                getter = eval(
                    'lambda self: self._SO_loadValue(%s)' %
                    repr(instanceName(name)))

            else:
                # If we aren't caching values, we just call the
                # function _SO_getValue, which fetches from the
                # database.
                getter = eval('lambda self: self._SO_getValue(%s)' % repr(name))
            setattr(soClass, rawGetterName(name), getter)

            # Here if the _get_columnName method isn't in the
            # definition, we add it with the default
            # _SO_get_columnName definition.
            if not hasattr(soClass, getterName(name)) or (name == 'childName'):
                setattr(soClass, getterName(name), getter)
                sqlmeta._plainGetters[name] = 1

            #################################################
            # Create the setter function(s)
            # Much like creating the getters, we will create
            # _SO_set_columnName methods, and then alias them
            # to _set_columnName if the user hasn't defined
            # those methods themself.

            # @@: This is lame; immutable right now makes it unsettable,
            # making the table read-only
            if not column.immutable:
                # We start by just using the _SO_setValue method
                setter = eval(
                    'lambda self, val: self._SO_setValue'
                    '(%s, val, self.%s, self.%s)' % (
                        repr(name),
                        '_SO_from_python_%s' % name, '_SO_to_python_%s' % name))
                setattr(soClass, '_SO_from_python_%s' % name, column.from_python)
                setattr(soClass, '_SO_to_python_%s' % name, column.to_python)
                setattr(soClass, rawSetterName(name), setter)
                # Then do the aliasing
                if not hasattr(soClass, setterName(name)) or (name == 'childName'):
                    setattr(soClass, setterName(name), setter)
                    # We keep track of setters that haven't been
                    # overridden, because we can combine these
                    # set columns into one SQL UPDATE query.
                    sqlmeta._plainSetters[name] = 1

            ##################################################
            # Here we check if the column is a foreign key, in
            # which case we need to make another method that
            # fetches the key and constructs the sister
            # SQLObject instance.
            if column.foreignKey:

                # We go through the standard _SO_get_columnName deal
                # we're giving the object, not the ID of the
                # object this time:
                origName = column.origName
                if sqlmeta.cacheValues:
                    # self._SO_class_className is a reference
                    # to the class in question.
                    getter = eval(
                        'lambda self: self._SO_foreignKey'
                        '(self._SO_loadValue(%r), self._SO_class_%s, %s)' %
                        (instanceName(name), column.foreignKey,
                         column.refColumn and repr(column.refColumn)))
                else:
                    # Same non-caching version as above.
                    getter = eval(
                        'lambda self: self._SO_foreignKey'
                        '(self._SO_getValue(%s), self._SO_class_%s, %s)' %
                        (repr(name), column.foreignKey,
                         column.refColumn and repr(column.refColumn)))
                setattr(soClass, rawGetterName(origName), getter)

                # And we set the _get_columnName version
                if not hasattr(soClass, getterName(origName)):
                    setattr(soClass, getterName(origName), getter)
                    sqlmeta._plainForeignGetters[origName] = 1

                if not column.immutable:
                    # The setter just gets the ID of the object,
                    # and then sets the real column.
                    setter = eval(
                        'lambda self, val: '
                        'setattr(self, %s, self._SO_getID(val, %s))' %
                        (repr(name), column.refColumn and repr(column.refColumn)))
                    setattr(soClass, rawSetterName(origName), setter)
                    if not hasattr(soClass, setterName(origName)):
                        setattr(soClass, setterName(origName), setter)
                        sqlmeta._plainForeignSetters[origName] = 1

                classregistry.registry(sqlmeta.registry).addClassCallback(
                    column.foreignKey,
                    lambda foreign, me, attr: setattr(me, attr, foreign),
                    soClass, '_SO_class_%s' % column.foreignKey)

            if column.alternateMethodName:
                func = eval(
                    'lambda cls, val, connection=None: '
                    'cls._SO_fetchAlternateID(%s, %s, val, connection=connection)'
                    % (repr(column.name), repr(column.dbName)))
                setattr(soClass, column.alternateMethodName, classmethod(func))

            if changeSchema:
                conn = connection or soClass._connection
                conn.addColumn(sqlmeta.table, column)

            if soClass._SO_finishedClassCreation:
                makeProperties(soClass)

            for func in post_funcs:
                func(soClass, column)

        @classmethod
        def addColumnsFromDatabase(sqlmeta, connection=None):
            soClass = sqlmeta.soClass
            conn = connection or soClass._connection
            for columnDef in conn.columnsFromSchema(sqlmeta.table, soClass):
                if columnDef.name not in sqlmeta.columnDefinitions:
                    if isinstance(columnDef.name, unicode_type) and PY2:
                        columnDef.name = columnDef.name.encode('ascii')
                    sqlmeta.addColumn(columnDef)

        @classmethod
        def delColumn(cls, column, changeSchema=False, connection=None):
            sqlmeta = cls
            soClass = sqlmeta.soClass
            if isinstance(column, str):
                if column in sqlmeta.columns:
                    column = sqlmeta.columns[column]
                elif column + 'ID' in sqlmeta.columns:
                    column = sqlmeta.columns[column + 'ID']
                else:
                    raise ValueError('Unknown column ' + column)
            if isinstance(column, col.Col):
                for c in sqlmeta.columns.values():
                    if column is c.columnDef:
                        column = c
                        break
                else:
                    raise IndexError(
                        "Column with definition %r not found" % column)
            post_funcs = []
            cls.send(events.DeleteColumnSignal, cls.soClass, connection,
                     column.name, column, post_funcs)
            name = column.name
            del sqlmeta.columns[name]
            del sqlmeta.columnDefinitions[name]
            sqlmeta.columnList.remove(column)
            delattr(soClass, rawGetterName(name))
            if name in sqlmeta._plainGetters:
                delattr(soClass, getterName(name))
            delattr(soClass, rawSetterName(name))
            if name in sqlmeta._plainSetters:
                delattr(soClass, setterName(name))
            if column.foreignKey:
                delattr(soClass,
                        rawGetterName(soClass.sqlmeta.style.
                                      instanceIDAttrToAttr(name)))
                if name in sqlmeta._plainForeignGetters:
                    delattr(soClass, getterName(name))
                delattr(soClass,
                        rawSetterName(soClass.sqlmeta.style.
                                      instanceIDAttrToAttr(name)))
                if name in sqlmeta._plainForeignSetters:
                    delattr(soClass, setterName(name))
            if column.alternateMethodName:
                delattr(soClass, column.alternateMethodName)

            if changeSchema:
                conn = connection or soClass._connection
                conn.delColumn(sqlmeta, column)

            if soClass._SO_finishedClassCreation:
                unmakeProperties(soClass)
                makeProperties(soClass)

            for func in post_funcs:
                func(soClass, column)

        ########################################
        # Join handling
        ########################################

        @classmethod
        def addJoin(cls, joinDef):
            sqlmeta = cls
            soClass = cls.soClass
            # The name of the method we'll create.  If it's
            # automatically generated, it's generated by the
            # join class.
            join = joinDef.withClass(soClass)
            meth = join.joinMethodName

            sqlmeta.joins.append(join)
            index = len(sqlmeta.joins) - 1
            if joinDef not in sqlmeta.joinDefinitions:
                sqlmeta.joinDefinitions.append(joinDef)

            # The function fetches the join by index, and
            # then lets the join object do the rest of the
            # work:
            func = eval(
                'lambda self: self.sqlmeta.joins[%i].performJoin(self)' % index)

            # And we do the standard _SO_get_... _get_... deal
            setattr(soClass, rawGetterName(meth), func)
            if not hasattr(soClass, getterName(meth)):
                setattr(soClass, getterName(meth), func)
                sqlmeta._plainJoinGetters[meth] = 1

            # Some joins allow you to remove objects from the
            # join.
            if hasattr(join, 'remove'):
                # Again, we let it do the remove, and we do the
                # standard naming trick.
                func = eval(
                    'lambda self, obj: self.sqlmeta.joins[%i].remove(self, obj)' %
                    index)
                setattr(soClass, '_SO_remove' + join.addRemoveName, func)
                if not hasattr(soClass, 'remove' + join.addRemoveName):
                    setattr(soClass, 'remove' + join.addRemoveName, func)
                    sqlmeta._plainJoinRemovers[meth] = 1

            # Some joins allow you to add objects.
            if hasattr(join, 'add'):
                # And again...
                func = eval(
                    'lambda self, obj: self.sqlmeta.joins[%i].add(self, obj)' %
                    index)
                setattr(soClass, '_SO_add' + join.addRemoveName, func)
                if not hasattr(soClass, 'add' + join.addRemoveName):
                    setattr(soClass, 'add' + join.addRemoveName, func)
                    sqlmeta._plainJoinAdders[meth] = 1

            if soClass._SO_finishedClassCreation:
                makeProperties(soClass)

        @classmethod
        def delJoin(sqlmeta, joinDef):
            soClass = sqlmeta.soClass
            for join in sqlmeta.joins:
                # previously deleted joins will be None, so it must
                # be skipped or it'll error out on the next line.
                if join is None:
                    continue
                if joinDef is join.joinDef:
                    break
            else:
                raise IndexError(
                    "Join %r not found in class %r (from %r)"
                    % (joinDef, soClass, sqlmeta.joins))
            meth = join.joinMethodName
            sqlmeta.joinDefinitions.remove(joinDef)
            for i in range(len(sqlmeta.joins)):
                if sqlmeta.joins[i] is join:
                    # Have to leave None, because we refer to joins
                    # by index.
                    sqlmeta.joins[i] = None
            delattr(soClass, rawGetterName(meth))
            if meth in sqlmeta._plainJoinGetters:
                delattr(soClass, getterName(meth))
            if hasattr(join, 'remove'):
                delattr(soClass, '_SO_remove' + join.addRemovePrefix)
                if meth in sqlmeta._plainJoinRemovers:
                    delattr(soClass, 'remove' + join.addRemovePrefix)
            if hasattr(join, 'add'):
                delattr(soClass, '_SO_add' + join.addRemovePrefix)
                if meth in sqlmeta._plainJoinAdders:
                    delattr(soClass, 'add' + join.addRemovePrefix)

            if soClass._SO_finishedClassCreation:
                unmakeProperties(soClass)
                makeProperties(soClass)

        ########################################
        # Indexes
        ########################################

        @classmethod
        def addIndex(cls, indexDef):
            cls.indexDefinitions.append(indexDef)
            index = indexDef.withClass(cls.soClass)
            cls.indexes.append(index)
            setattr(cls.soClass, index.name, index)

        ########################################
        # Utility methods
        ########################################

        @classmethod
        def getColumns(sqlmeta):
            return sqlmeta.columns.copy()

        def asDict(self):
            """
            Return the object as a dictionary of columns to values.
            """
            result = {}
            for key in self.getColumns():
                result[key] = getattr(self.instance, key)
            result['id'] = self.instance.id
            return result

        @classmethod
        def expireAll(sqlmeta, connection=None):
            """
            Expire all instances of this class.
            """
            soClass = sqlmeta.soClass
            connection = connection or soClass._connection
            cache_set = connection.cache
            cache_set.weakrefAll(soClass)
            for item in cache_set.getAll(soClass):
                item.expire()

    sqlhub = dbconnection.ConnectionHub()

    # Turning it on gives earlier warning about things
    # that will be deprecated (having this off we won't flood people
    # with warnings right away).
    warnings_level = 1
    exception_level = None
    # Current levels:
    #  1) Actively deprecated
    #  2) Deprecated after 1
    #  3) Deprecated after 2

    def deprecated(message, level=1, stacklevel=2):
        if exception_level is not None and exception_level <= level:
            raise NotImplementedError(message)
        if warnings_level is not None and warnings_level <= level:
            warnings.warn(message, DeprecationWarning, stacklevel=stacklevel)

    # if sys.version_info[:2] < (2, 6):
    #     deprecated("Support for Python 2.5 has been declared obsolete "
    #     "and will be removed in the next release of SQLObject")

    def setDeprecationLevel(warning=1, exception=None):
        """
        Set the deprecation level for SQLObject.  Low levels are more
        actively being deprecated.  Any warning at a level at or below
        ``warning`` will give a warning.  Any warning at a level at or
        below ``exception`` will give an exception.  You can use a higher
        ``exception`` level for tests to help upgrade your code.  ``None``
        for either value means never warn or raise exceptions.

        The levels currently mean:

          1) Deprecated in current version.  Will be removed in next version.

          2) Planned to deprecate in next version, remove later.

          3) Planned to deprecate sometime, remove sometime much later.

        As the SQLObject versions progress, the deprecation level of
        specific features will go down, indicating the advancing nature of
        the feature's doom.  We'll try to keep features at 1 for a major
        revision.

        As time continues there may be a level 0, which will give a useful
        error message (better than ``AttributeError``) but where the
        feature has been fully removed.
        """
        global warnings_level, exception_level
        warnings_level = warning
        exception_level = exception

    class _sqlmeta_attr(object):

        def __init__(self, name, deprecation_level):
            self.name = name
            self.deprecation_level = deprecation_level

        def __get__(self, obj, type=None):
            if self.deprecation_level is not None:
                deprecated(
                    'Use of this attribute should be replaced with '
                    '.sqlmeta.%s' % self.name, level=self.deprecation_level)
            return getattr((type or obj).sqlmeta, self.name)

    _postponed_local = local()

    # SQLObject is the superclass for all SQLObject classes, of
    # course.  All the deeper magic is done in MetaSQLObject, and
    # only lesser magic is done here.  All the actual work is done
    # here, though -- just automatic method generation (like
    # methods and properties for each column) is done in
    # MetaSQLObject.

    class SQLObject(with_metaclass(declarative.DeclarativeMeta, object)):

        _connection = sqlhub

        sqlmeta = sqlmeta

        # DSM: The _inheritable attribute controls wheter the class can by
        # DSM: inherited 'logically' with a foreignKey and a back reference.
        _inheritable = False  # Is this class inheritable?
        _parent = None  # A reference to the parent instance
        childName = None  # Children name (to be able to get a subclass)

        # The law of Demeter: the class should not call another classes by name
        SelectResultsClass = SelectResults

        def __classinit__(cls, new_attrs):

            # This is true if we're initializing the SQLObject class,
            # instead of a subclass:
            is_base = cls.__bases__ == (object,)

            cls._SO_setupSqlmeta(new_attrs, is_base)

            implicitColumns = _collectAttributes(cls, new_attrs, col.Col)
            implicitJoins = _collectAttributes(cls, new_attrs, joins.Join)
            implicitIndexes = _collectAttributes(cls, new_attrs,
                                                 index.DatabaseIndex)

            if not is_base:
                cls._SO_cleanDeprecatedAttrs(new_attrs)

            if '_connection' in new_attrs:
                connection = new_attrs['_connection']
                del cls._connection
                assert 'connection' not in new_attrs
            elif 'connection' in new_attrs:
                connection = new_attrs['connection']
                del cls.connection
            else:
                connection = None

            cls._SO_finishedClassCreation = False

            ######################################################
            # Set some attributes to their defaults, if necessary.
            # First we get the connection:
            if not connection and not getattr(cls, '_connection', None):
                mod = sys.modules[cls.__module__]
                # See if there's a __connection__ global in
                # the module, use it if there is.
                if hasattr(mod, '__connection__'):
                    connection = mod.__connection__

            # Do not check hasattr(cls, '_connection') here - it is possible
            # SQLObject parent class has a connection attribute that came
            # from sqlhub, e.g.; check __dict__ only.
            if connection and ('_connection' not in cls.__dict__):
                cls.setConnection(connection)

            sqlmeta = cls.sqlmeta

            # We have to check if there are columns in the inherited
            # _columns where the attribute has been set to None in this
            # class.  If so, then we need to remove that column from
            # _columns.
            for key in sqlmeta.columnDefinitions.keys():
                if (key in new_attrs and new_attrs[key] is None):
                    del sqlmeta.columnDefinitions[key]

            for column in sqlmeta.columnDefinitions.values():
                sqlmeta.addColumn(column)

            for column in implicitColumns:
                sqlmeta.addColumn(column)

            # Now the class is in an essentially OK-state, so we can
            # set up any magic attributes:
            declarative.setup_attributes(cls, new_attrs)

            if sqlmeta.fromDatabase:
                sqlmeta.addColumnsFromDatabase()

            for j in implicitJoins:
                sqlmeta.addJoin(j)
            for i in implicitIndexes:
                sqlmeta.addIndex(i)

            def order_getter(o):
                return o.creationOrder
            sqlmeta.columnList.sort(key=order_getter)
            sqlmeta.indexes.sort(key=order_getter)
            sqlmeta.indexDefinitions.sort(key=order_getter)
            # Joins cannot be sorted because addJoin created accessors
            # that remember indexes.
            # sqlmeta.joins.sort(key=order_getter)
            sqlmeta.joinDefinitions.sort(key=order_getter)

            # We don't setup the properties until we're finished with the
            # batch adding of all the columns...
            cls._notifyFinishClassCreation()
            cls._SO_finishedClassCreation = True
            makeProperties(cls)

            # We use the magic "q" attribute for accessing lazy
            # SQL where-clause generation.  See the sql module for
            # more.
            if not is_base:
                cls.q = sqlbuilder.SQLObjectTable(cls)
                cls.j = sqlbuilder.SQLObjectTableWithJoins(cls)

            classregistry.registry(sqlmeta.registry).addClass(cls)

        @classmethod
        def _SO_setupSqlmeta(cls, new_attrs, is_base):
            """
            This fixes up the sqlmeta attribute.  It handles both the case
            where no sqlmeta was given (in which we need to create another
            subclass), or the sqlmeta given doesn't have the proper
            inheritance.  Lastly it calls sqlmeta.setClass, which handles
            much of the setup.
            """
            if ('sqlmeta' not in new_attrs and not is_base):
                # We have to create our own subclass, usually.
                # type(className, bases_tuple, attr_dict) creates a new subclass.
                cls.sqlmeta = type('sqlmeta', (cls.sqlmeta,), {})
            if not issubclass(cls.sqlmeta, sqlmeta):
                # We allow no superclass and an object superclass, instead
                # of inheriting from sqlmeta; but in that case we replace
                # the class and just move over its attributes:
                assert cls.sqlmeta.__bases__ in ((), (object,)), (
                    "If you do not inherit your sqlmeta class from "
                    "sqlobject.sqlmeta, it must not inherit from any other "
                    "class (your sqlmeta inherits from: %s)"
                    % cls.sqlmeta.__bases__)
                for base in cls.__bases__:
                    superclass = getattr(base, 'sqlmeta', None)
                    if superclass:
                        break
                else:
                    assert 0, (
                        "No sqlmeta class could be found in any superclass "
                        "(while fixing up sqlmeta %r inheritance)"
                        % cls.sqlmeta)
                values = dict(cls.sqlmeta.__dict__)
                for key in list(values.keys()):
                    if key.startswith('__') and key.endswith('__'):
                        # Magic values shouldn't be passed through:
                        del values[key]
                cls.sqlmeta = type('sqlmeta', (superclass,), values)

            if not is_base:  # Do not pollute the base sqlmeta class
                cls.sqlmeta.setClass(cls)

        @classmethod
        def _SO_cleanDeprecatedAttrs(cls, new_attrs):
            """
            This removes attributes on SQLObject subclasses that have
            been deprecated; they are moved to the sqlmeta class, and
            a deprecation warning is given.
            """
            for attr in ():
                if attr in new_attrs:
                    deprecated("%r is deprecated and read-only; please do "
                               "not use it in your classes until it is fully "
                               "deprecated" % attr, level=1, stacklevel=5)

        @classmethod
        def get(cls, id, connection=None, selectResults=None):

            assert id is not None, \
                'None is not a possible id for %s' % cls.__name__

            id = cls.sqlmeta.idType(id)

            if connection is None:
                cache = cls._connection.cache
            else:
                cache = connection.cache

            # This whole sequence comes from Cache.CacheFactory's
            # behavior, where a None returned means a cache miss.
            val = cache.get(id, cls)
            if val is None:
                try:
                    val = cls(_SO_fetch_no_create=1)
                    val._SO_validatorState = sqlbuilder.SQLObjectState(val)
                    val._init(id, connection, selectResults)
                    cache.put(id, cls, val)
                finally:
                    cache.finishPut(cls)
            elif selectResults and not val.sqlmeta.dirty:
                val._SO_writeLock.acquire()
                try:
                    val._SO_selectInit(selectResults)
                    val.sqlmeta.expired = False
                finally:
                    val._SO_writeLock.release()
            return val

        @classmethod
        def _notifyFinishClassCreation(cls):
            pass

        def _init(self, id, connection=None, selectResults=None):
            assert id is not None
            # This function gets called only when the object is
            # created, unlike __init__ which would be called
            # anytime the object was returned from cache.
            self.id = id
            self._SO_writeLock = threading.Lock()

            # If no connection was given, we'll inherit the class
            # instance variable which should have a _connection
            # attribute.
            if (connection is not None) and \
                    (getattr(self, '_connection', None) is not connection):
                self._connection = connection
                # Sometimes we need to know if this instance is
                # global or tied to a particular connection.
                # This flag tells us that:
                self.sqlmeta._perConnection = True

            if not selectResults:
                dbNames = [col.dbName for col in self.sqlmeta.columnList]
                selectResults = self._connection._SO_selectOne(self, dbNames)
                if not selectResults:
                    raise SQLObjectNotFound(
                        "The object %s by the ID %s does not exist" % (
                            self.__class__.__name__, self.id))
            self._SO_selectInit(selectResults)
            self._SO_createValues = {}
            self.sqlmeta.dirty = False

        def _SO_loadValue(self, attrName):
            try:
                return getattr(self, attrName)
            except AttributeError:
                try:
                    self._SO_writeLock.acquire()
                    try:
                        # Maybe, just in the moment since we got the lock,
                        # some other thread did a _SO_loadValue and we
                        # have the attribute!  Let's try and find out!  We
                        # can keep trying this all day and still beat the
                        # performance on the database call (okay, we can
                        # keep trying this for a few msecs at least)...
                        result = getattr(self, attrName)
                    except AttributeError:
                        pass
                    else:
                        return result
                    self.sqlmeta.expired = False
                    dbNames = [col.dbName for col in self.sqlmeta.columnList]
                    selectResults = self._connection._SO_selectOne(self, dbNames)
                    if not selectResults:
                        raise SQLObjectNotFound(
                            "The object %s by the ID %s has been deleted" % (
                                self.__class__.__name__, self.id))
                    self._SO_selectInit(selectResults)
                    result = getattr(self, attrName)
                    return result
                finally:
                    self._SO_writeLock.release()

        def sync(self):
            if self.sqlmeta.lazyUpdate and self._SO_createValues:
                self.syncUpdate()
            self._SO_writeLock.acquire()
            try:
                dbNames = [col.dbName for col in self.sqlmeta.columnList]
                selectResults = self._connection._SO_selectOne(self, dbNames)
                if not selectResults:
                    raise SQLObjectNotFound(
                        "The object %s by the ID %s has been deleted" % (
                            self.__class__.__name__, self.id))
                self._SO_selectInit(selectResults)
                self.sqlmeta.expired = False
            finally:
                self._SO_writeLock.release()

        def syncUpdate(self):
            if not self._SO_createValues:
                return
            self._SO_writeLock.acquire()
            try:
                if self.sqlmeta.columns:
                    columns = self.sqlmeta.columns
                    values = [(columns[v[0]].dbName, v[1])
                              for v in sorted(
                                  self._SO_createValues.items(),
                                  key=lambda c: columns[c[0]].creationOrder)]
                    self._connection._SO_update(self, values)
                self.sqlmeta.dirty = False
                self._SO_createValues = {}
            finally:
                self._SO_writeLock.release()

            post_funcs = []
            self.sqlmeta.send(events.RowUpdatedSignal, self, post_funcs)
            for func in post_funcs:
                func(self)

        def expire(self):
            if self.sqlmeta.expired:
                return
            self._SO_writeLock.acquire()
            try:
                if self.sqlmeta.expired:
                    return
                for column in self.sqlmeta.columnList:
                    delattr(self, instanceName(column.name))
                self.sqlmeta.expired = True
                self._connection.cache.expire(self.id, self.__class__)
                self._SO_createValues = {}
            finally:
                self._SO_writeLock.release()

        def _SO_setValue(self, name, value, from_python, to_python):
            # This is the place where we actually update the
            # database.

            # If we are _creating, the object doesn't yet exist
            # in the database, and we can't insert it until all
            # the parts are set.  So we just keep them in a
            # dictionary until later:
            d = {name: value}
            if not self.sqlmeta._creating and \
                    not getattr(self.sqlmeta, "row_update_sig_suppress", False):
                self.sqlmeta.send(events.RowUpdateSignal, self, d)
            if len(d) != 1 or name not in d:
                # Already called RowUpdateSignal, don't call it again
                # inside .set()
                self.sqlmeta.row_update_sig_suppress = True
                self.set(**d)
                del self.sqlmeta.row_update_sig_suppress
            value = d[name]
            if from_python:
                dbValue = from_python(value, self._SO_validatorState)
            else:
                dbValue = value
            if to_python:
                value = to_python(dbValue, self._SO_validatorState)
            if self.sqlmeta._creating or self.sqlmeta.lazyUpdate:
                self.sqlmeta.dirty = True
                self._SO_createValues[name] = dbValue
                setattr(self, instanceName(name), value)
                return

            self._connection._SO_update(
                self, [(self.sqlmeta.columns[name].dbName,
                        dbValue)])

            if self.sqlmeta.cacheValues:
                setattr(self, instanceName(name), value)

            post_funcs = []
            self.sqlmeta.send(events.RowUpdatedSignal, self, post_funcs)
            for func in post_funcs:
                func(self)

        def set(self, _suppress_set_sig=False, **kw):
            if not self.sqlmeta._creating and \
                    not getattr(self.sqlmeta, "row_update_sig_suppress", False) \
                    and not _suppress_set_sig:
                self.sqlmeta.send(events.RowUpdateSignal, self, kw)
            # set() is used to update multiple values at once,
            # potentially with one SQL statement if possible.

            # Filter out items that don't map to column names.
            # Those will be set directly on the object using
            # setattr(obj, name, value).
            def is_column(_c):
                return _c in self.sqlmeta._plainSetters

            def f_is_column(item):
                return is_column(item[0])

            def f_not_column(item):
                return not is_column(item[0])
            items = kw.items()
            extra = dict(filter(f_not_column, items))
            kw = dict(filter(f_is_column, items))

            # _creating is special, see _SO_setValue
            if self.sqlmeta._creating or self.sqlmeta.lazyUpdate:
                for name, value in kw.items():
                    from_python = getattr(self, '_SO_from_python_%s' % name, None)
                    if from_python:
                        kw[name] = dbValue = from_python(value,
                                                         self._SO_validatorState)
                    else:
                        dbValue = value
                    to_python = getattr(self, '_SO_to_python_%s' % name, None)
                    if to_python:
                        value = to_python(dbValue, self._SO_validatorState)
                    setattr(self, instanceName(name), value)

                self._SO_createValues.update(kw)

                for name, value in extra.items():
                    try:
                        getattr(self.__class__, name)
                    except AttributeError:
                        if name not in self.sqlmeta.columns:
                            raise TypeError(
                                "%s.set() got an unexpected keyword argument "
                                "%s" % (self.__class__.__name__, name))
                    try:
                        setattr(self, name, value)
                    except AttributeError as e:
                        raise AttributeError('%s (with attribute %r)' % (e, name))

                self.sqlmeta.dirty = True
                return

            self._SO_writeLock.acquire()

            try:
                # We have to go through and see if the setters are
                # "plain", that is, if the user has changed their
                # definition in any way (put in something that
                # normalizes the value or checks for consistency,
                # for instance).  If so then we have to use plain
                # old setattr() to change the value, since we can't
                # read the user's mind.  We'll combine everything
                # else into a single UPDATE, if necessary.
                toUpdate = {}
                for name, value in kw.items():
                    from_python = getattr(self, '_SO_from_python_%s' % name, None)
                    if from_python:
                        dbValue = from_python(value, self._SO_validatorState)
                    else:
                        dbValue = value
                    to_python = getattr(self, '_SO_to_python_%s' % name, None)
                    if to_python:
                        value = to_python(dbValue, self._SO_validatorState)
                    if self.sqlmeta.cacheValues:
                        setattr(self, instanceName(name), value)
                    toUpdate[name] = dbValue
                for name, value in extra.items():
                    try:
                        getattr(self.__class__, name)
                    except AttributeError:
                        if name not in self.sqlmeta.columns:
                            raise TypeError(
                                "%s.set() got an unexpected keyword argument "
                                "%s" % (self.__class__.__name__, name))
                    try:
                        setattr(self, name, value)
                    except AttributeError as e:
                        raise AttributeError('%s (with attribute %r)' % (e, name))

                if toUpdate:
                    toUpdate = sorted(
                        toUpdate.items(),
                        key=lambda c: self.sqlmeta.columns[c[0]].creationOrder)
                    args = [(self.sqlmeta.columns[name].dbName, value)
                            for name, value in toUpdate]
                    self._connection._SO_update(self, args)
            finally:
                self._SO_writeLock.release()

            post_funcs = []
            self.sqlmeta.send(events.RowUpdatedSignal, self, post_funcs)
            for func in post_funcs:
                func(self)

        def _SO_selectInit(self, row):
            for _col, colValue in zip(self.sqlmeta.columnList, row):
                if _col.to_python:
                    colValue = _col.to_python(colValue, self._SO_validatorState)
                setattr(self, instanceName(_col.name), colValue)

        def _SO_getValue(self, name):
            # Retrieves a single value from the database.  Simple.
            assert not self.sqlmeta._obsolete, (
                "%s with id %s has become obsolete"
                % (self.__class__.__name__, self.id))
            # @@: do we really need this lock?
            # self._SO_writeLock.acquire()
            column = self.sqlmeta.columns[name]
            results = self._connection._SO_selectOne(self, [column.dbName])
            # self._SO_writeLock.release()
            assert results is not None, "%s with id %s is not in the database" % (
                self.__class__.__name__, self.id)
            value = results[0]
            if column.to_python:
                value = column.to_python(value, self._SO_validatorState)
            return value

        def _SO_foreignKey(self, value, joinClass, idName=None):
            if value is None:
                return None
            if self.sqlmeta._perConnection:
                connection = self._connection
            else:
                connection = None
            if idName is None:  # Get by id
                return joinClass.get(value, connection=connection)
            return joinClass.select(
                getattr(joinClass.q, idName) == value,
                connection=connection).getOne()

        def __init__(self, **kw):
            # If we are the outmost constructor of a hiearchy of
            # InheritableSQLObjects (or simlpy _the_ constructor of a "normal"
            # SQLObject), we create a threadlocal list that collects the
            # RowCreatedSignals, and executes them if this very constructor is left
            try:
                _postponed_local.postponed_calls
                postponed_created = False
            except AttributeError:
                _postponed_local.postponed_calls = []
                postponed_created = True

            try:
                # We shadow the sqlmeta class with an instance of sqlmeta
                # that points to us (our sqlmeta buddy object; where the
                # sqlmeta class is our class's buddy class)
                self.sqlmeta = self.__class__.sqlmeta(self)
                # The get() classmethod/constructor uses a magic keyword
                # argument when it wants an empty object, fetched from the
                # database.  So we have nothing more to do in that case:
                if '_SO_fetch_no_create' in kw:
                    return

                post_funcs = []
                self.sqlmeta.send(events.RowCreateSignal, self, kw, post_funcs)

                # Pass the connection object along if we were given one.
                if 'connection' in kw:
                    connection = kw.pop('connection')
                    if getattr(self, '_connection', None) is not connection:
                        self._connection = connection
                        self.sqlmeta._perConnection = True

                self._SO_writeLock = threading.Lock()

                if 'id' in kw:
                    id = self.sqlmeta.idType(kw['id'])
                    del kw['id']
                else:
                    id = None

                self._create(id, **kw)

                for func in post_funcs:
                    func(self)
            finally:
                # if we are the creator of the tl-storage, we
                # have to exectute and under all circumstances
                # remove the tl-storage
                if postponed_created:
                    try:
                        for func in _postponed_local.postponed_calls:
                            func()
                    finally:
                        del _postponed_local.postponed_calls

        def _create(self, id, **kw):

            self.sqlmeta._creating = True
            self._SO_createValues = {}
            self._SO_validatorState = sqlbuilder.SQLObjectState(self)

            # First we do a little fix-up on the keywords we were
            # passed:
            for column in self.sqlmeta.columnList:

                # Then we check if the column wasn't passed in, and
                # if not we try to get the default.
                if column.name not in kw and column.foreignName not in kw:
                    default = column.default

                    # If we don't get it, it's an error:
                    # If we specified an SQL DEFAULT, then we should use that
                    if default is NoDefault:
                        if column.defaultSQL is None:
                            raise TypeError(
                                "%s() did not get expected keyword argument "
                                "'%s'" % (self.__class__.__name__, column.name))
                        else:
                            # There is defaultSQL for the column -
                            # do not put the column to kw
                            # so that the backend creates the value.
                            continue

                    # Otherwise we put it in as though they did pass
                    # that keyword:

                    kw[column.name] = default

            self.set(**kw)

            # Then we finalize the process:
            self._SO_finishCreate(id)

        def _SO_finishCreate(self, id=None):
            # Here's where an INSERT is finalized.
            # These are all the column values that were supposed
            # to be set, but were delayed until now:
            setters = self._SO_createValues.items()
            setters = sorted(
                setters, key=lambda c: self.sqlmeta.columns[c[0]].creationOrder)
            # Here's their database names:
            names = [self.sqlmeta.columns[v[0]].dbName for v in setters]
            values = [v[1] for v in setters]
            # Get rid of _SO_create*, we aren't creating anymore.
            # Doesn't have to be threadsafe because we're still in
            # new(), which doesn't need to be threadsafe.
            self.sqlmeta.dirty = False
            if not self.sqlmeta.lazyUpdate:
                del self._SO_createValues
            else:
                self._SO_createValues = {}
            del self.sqlmeta._creating

            # Do the insert -- most of the SQL in this case is left
            # up to DBConnection, since getting a new ID is
            # non-standard.
            id = self._connection.queryInsertID(self,
                                                id, names, values)
            cache = self._connection.cache
            cache.created(id, self.__class__, self)
            self._init(id)
            post_funcs = []
            kw = dict([('class', self.__class__), ('id', id)])

            def _send_RowCreatedSignal():
                self.sqlmeta.send(events.RowCreatedSignal, self, kw, post_funcs)
                for func in post_funcs:
                    func(self)
            _postponed_local.postponed_calls.append(_send_RowCreatedSignal)

        def _SO_getID(self, obj, refColumn=None):
            return getID(obj, refColumn)

        @classmethod
        def _findAlternateID(cls, name, dbName, value, connection=None):
            if isinstance(name, str):
                name = (name,)
                value = (value,)
            if len(name) != len(value):
                raise ValueError(
                    "'column' and 'value' tuples must be of the same size")
            new_value = []
            for n, v in zip(name, value):
                from_python = getattr(cls, '_SO_from_python_' + n)
                if from_python:
                    v = from_python(
                        v, sqlbuilder.SQLObjectState(cls, connection=connection))
                new_value.append(v)
            condition = sqlbuilder.AND(
                *[getattr(cls.q, _n) == _v for _n, _v in zip(name, new_value)])
            return (connection or cls._connection)._SO_selectOneAlt(
                cls,
                [cls.sqlmeta.idName] +
                [column.dbName for column in cls.sqlmeta.columnList],
                condition), None

        @classmethod
        def _SO_fetchAlternateID(cls, name, dbName, value, connection=None,
                                 idxName=None):
            result, obj = cls._findAlternateID(name, dbName, value, connection)
            if not result:
                if idxName is None:
                    raise SQLObjectNotFound(
                        "The %s by alternateID %s = %s does not exist" % (
                            cls.__name__, name, repr(value)))
                else:
                    names = []
                    for i in range(len(name)):
                        names.append("%s = %s" % (name[i], repr(value[i])))
                    names = ', '.join(names)
                    raise SQLObjectNotFound(
                        "The %s by unique index %s(%s) does not exist" % (
                            cls.__name__, idxName, names))
            if obj:
                return obj
            if connection:
                obj = cls.get(result[0], connection=connection,
                              selectResults=result[1:])
            else:
                obj = cls.get(result[0], selectResults=result[1:])
            return obj

        @classmethod
        def _SO_depends(cls):
            return findDependencies(cls.__name__, cls.sqlmeta.registry)

        @classmethod
        def select(cls, clause=None, clauseTables=None,
                   orderBy=NoDefault, limit=None,
                   lazyColumns=False, reversed=False,
                   distinct=False, connection=None,
                   join=None, forUpdate=False):
            return cls.SelectResultsClass(cls, clause,
                                          clauseTables=clauseTables,
                                          orderBy=orderBy,
                                          limit=limit,
                                          lazyColumns=lazyColumns,
                                          reversed=reversed,
                                          distinct=distinct,
                                          connection=connection,
                                          join=join, forUpdate=forUpdate)

        @classmethod
        def selectBy(cls, connection=None, **kw):
            conn = connection or cls._connection
            return cls.SelectResultsClass(cls,
                                          conn._SO_columnClause(cls, kw),
                                          connection=conn)

        @classmethod
        def tableExists(cls, connection=None):
            conn = connection or cls._connection
            return conn.tableExists(cls.sqlmeta.table)

        @classmethod
        def dropTable(cls, ifExists=False, dropJoinTables=True, cascade=False,
                      connection=None):
            conn = connection or cls._connection
            if ifExists and not cls.tableExists(connection=conn):
                return
            extra_sql = []
            post_funcs = []
            cls.sqlmeta.send(events.DropTableSignal, cls, connection,
                             extra_sql, post_funcs)
            conn.dropTable(cls.sqlmeta.table, cascade)
            if dropJoinTables:
                cls.dropJoinTables(ifExists=ifExists, connection=conn)
            for sql in extra_sql:
                connection.query(sql)
            for func in post_funcs:
                func(cls, conn)

        @classmethod
        def createTable(cls, ifNotExists=False, createJoinTables=True,
                        createIndexes=True, applyConstraints=True,
                        connection=None):
            conn = connection or cls._connection
            if ifNotExists and cls.tableExists(connection=conn):
                return
            extra_sql = []
            post_funcs = []
            cls.sqlmeta.send(events.CreateTableSignal, cls, connection,
                             extra_sql, post_funcs)
            constraints = conn.createTable(cls)
            if applyConstraints:
                for constraint in constraints:
                    conn.query(constraint)
            else:
                extra_sql.extend(constraints)
            if createJoinTables:
                cls.createJoinTables(ifNotExists=ifNotExists,
                                     connection=conn)
            if createIndexes:
                cls.createIndexes(ifNotExists=ifNotExists,
                                  connection=conn)
            for func in post_funcs:
                func(cls, conn)
            return extra_sql

        @classmethod
        def createTableSQL(cls, createJoinTables=True, createIndexes=True,
                           connection=None):
            conn = connection or cls._connection
            sql, constraints = conn.createTableSQL(cls)
            if createJoinTables:
                join_sql = cls.createJoinTablesSQL(connection=conn)
                if join_sql:
                    sql += ';\n' + join_sql
            if createIndexes:
                index_sql = cls.createIndexesSQL(connection=conn)
                if index_sql:
                    sql += ';\n' + index_sql
            return sql, constraints

        @classmethod
        def createJoinTables(cls, ifNotExists=False, connection=None):
            conn = connection or cls._connection
            for join in cls._getJoinsToCreate():
                if (ifNotExists and
                        conn.tableExists(join.intermediateTable)):
                    continue
                conn._SO_createJoinTable(join)

        @classmethod
        def createJoinTablesSQL(cls, connection=None):
            conn = connection or cls._connection
            sql = []
            for join in cls._getJoinsToCreate():
                sql.append(conn._SO_createJoinTableSQL(join))
            return ';\n'.join(sql)

        @classmethod
        def createIndexes(cls, ifNotExists=False, connection=None):
            conn = connection or cls._connection
            for _index in cls.sqlmeta.indexes:
                if not _index:
                    continue
                conn._SO_createIndex(cls, _index)

        @classmethod
        def createIndexesSQL(cls, connection=None):
            conn = connection or cls._connection
            sql = []
            for _index in cls.sqlmeta.indexes:
                if not _index:
                    continue
                sql.append(conn.createIndexSQL(cls, _index))
            return ';\n'.join(sql)

        @classmethod
        def _getJoinsToCreate(cls):
            joins = []
            for join in cls.sqlmeta.joins:
                if not join:
                    continue
                if not join.hasIntermediateTable() or \
                        not getattr(join, 'createRelatedTable', True):
                    continue
                if join.soClass.__name__ > join.otherClass.__name__:
                    continue
                joins.append(join)
            return joins

        @classmethod
        def dropJoinTables(cls, ifExists=False, connection=None):
            conn = connection or cls._connection
            for join in cls.sqlmeta.joins:
                if not join:
                    continue
                if not join.hasIntermediateTable() or \
                        not getattr(join, 'createRelatedTable', True):
                    continue
                if join.soClass.__name__ > join.otherClass.__name__:
                    continue
                if ifExists and \
                   not conn.tableExists(join.intermediateTable):
                    continue
                conn._SO_dropJoinTable(join)

        @classmethod
        def clearTable(cls, connection=None, clearJoinTables=True):
            # 3-03 @@: Maybe this should check the cache... but it's
            # kind of crude anyway, so...
            conn = connection or cls._connection
            conn.clearTable(cls.sqlmeta.table)
            if clearJoinTables:
                for join in cls._getJoinsToCreate():
                    conn.clearTable(join.intermediateTable)

        def destroySelf(self):
            post_funcs = []
            self.sqlmeta.send(events.RowDestroySignal, self, post_funcs)
            # Kills this object.  Kills it dead!

            klass = self.__class__

            # Free related joins on the base class
            for join in klass.sqlmeta.joins:
                if isinstance(join, joins.SORelatedJoin):
                    q = "DELETE FROM %s WHERE %s=%d" % (join.intermediateTable,
                                                        join.joinColumn, self.id)
                    self._connection.query(q)

            depends = []
            depends = self._SO_depends()
            for k in depends:
                # Free related joins
                for join in k.sqlmeta.joins:
                    if isinstance(join, joins.SORelatedJoin) and \
                            join.otherClassName == klass.__name__:
                        q = "DELETE FROM %s WHERE %s=%d" % (join.intermediateTable,
                                                            join.otherColumn,
                                                            self.id)
                        self._connection.query(q)

                cols = findDependantColumns(klass.__name__, k)

                # Don't confuse the rest of the process
                if len(cols) == 0:
                    continue

                query = []
                delete = setnull = restrict = False
                for _col in cols:
                    if _col.cascade is False:
                        # Found a restriction
                        restrict = True
                    query.append(getattr(k.q, _col.name) == self.id)
                    if _col.cascade == 'null':
                        setnull = _col.name
                    elif _col.cascade:
                        delete = True
                assert delete or setnull or restrict, (
                    "Class %s depends on %s accoriding to "
                    "findDependantColumns, but this seems inaccurate"
                    % (k, klass))
                query = sqlbuilder.OR(*query)
                results = k.select(query, connection=self._connection)
                if restrict:
                    if results.count():
                        # Restrictions only apply if there are
                        # matching records on the related table
                        raise SQLObjectIntegrityError(
                            "Tried to delete %s::%s but "
                            "table %s has a restriction against it" %
                            (klass.__name__, self.id, k.__name__))
                else:
                    for row in results:
                        if delete:
                            row.destroySelf()
                        else:
                            row.set(**{setnull: None})

            self.sqlmeta._obsolete = True
            self._connection._SO_delete(self)
            self._connection.cache.expire(self.id, self.__class__)

            for func in post_funcs:
                func(self)

            post_funcs = []
            self.sqlmeta.send(events.RowDestroyedSignal, self, post_funcs)
            for func in post_funcs:
                func(self)

        @classmethod
        def delete(cls, id, connection=None):
            obj = cls.get(id, connection=connection)
            obj.destroySelf()

        @classmethod
        def deleteMany(cls, where=NoDefault, connection=None):
            conn = connection or cls._connection
            conn.query(conn.sqlrepr(sqlbuilder.Delete(cls.sqlmeta.table, where)))

        @classmethod
        def deleteBy(cls, connection=None, **kw):
            conn = connection or cls._connection
            conn.query(conn.sqlrepr(sqlbuilder.Delete(
                cls.sqlmeta.table, conn._SO_columnClause(cls, kw))))

        def __repr__(self):
            if not hasattr(self, 'id'):
                # Object initialization not finished.  No attributes can be read.
                return '<%s (not initialized)>' % self.__class__.__name__
            return '<%s %r %s>' \
                   % (self.__class__.__name__,
                      self.id,
                      ' '.join(
                          ['%s=%s' % (name, repr(value))
                           for name, value in self._reprItems()]))

        def __sqlrepr__(self, db):
            return str(self.id)

        @classmethod
        def sqlrepr(cls, value, connection=None):
            return (connection or cls._connection).sqlrepr(value)

        @classmethod
        def coerceID(cls, value):
            if isinstance(value, cls):
                return value.id
            else:
                return cls.sqlmeta.idType(value)

        def _reprItems(self):
            items = []
            for _col in self.sqlmeta.columnList:
                value = getattr(self, _col.name)
                r = repr(value)
                if len(r) > 20:
                    value = r[:17] + "..." + r[-1]
                items.append((_col.name, value))
            return items

        @classmethod
        def setConnection(cls, value):
            if isinstance(value, string_type):
                value = dbconnection.connectionForURI(value)
            cls._connection = value

        def tablesUsedImmediate(self):
            return [self.__class__.q]

        # hash implementation

        def __hash__(self):
            # We hash on class name and id, since that should be
            # unique
            return hash((self.__class__.__name__, self.id))

        # Comparison

        def __eq__(self, other):
            if self.__class__ is other.__class__:
                if self.id == other.id:
                    return True
            return False

        def __ne__(self, other):
            return not self.__eq__(other)

        def __lt__(self, other):
            return NotImplemented

        def __le__(self, other):
            return NotImplemented

        def __gt__(self, other):
            return NotImplemented

        def __ge__(self, other):
            return NotImplemented

        # (De)serialization (pickle, etc.)

        def __getstate__(self):
            if self.sqlmeta._perConnection:
                from pickle import PicklingError
                raise PicklingError(
                    'Cannot pickle an SQLObject instance '
                    'that has a per-instance connection')
            if self.sqlmeta.lazyUpdate and self._SO_createValues:
                self.syncUpdate()
            d = self.__dict__.copy()
            del d['sqlmeta']
            del d['_SO_validatorState']
            del d['_SO_writeLock']
            del d['_SO_createValues']
            return d

        def __setstate__(self, d):
            self.__init__(_SO_fetch_no_create=1)
            self._SO_validatorState = sqlbuilder.SQLObjectState(self)
            self._SO_writeLock = threading.Lock()
            self._SO_createValues = {}
            self.__dict__.update(d)
            cls = self.__class__
            cache = self._connection.cache
            if cache.tryGet(self.id, cls) is not None:
                raise ValueError(
                    "Cannot unpickle %s row with id=%s - "
                    "a different instance with the id already exists "
                    "in the cache" % (cls.__name__, self.id))
            cache.created(self.id, cls, self)

    def setterName(name):
        return '_set_%s' % name

    def rawSetterName(name):
        return '_SO_set_%s' % name

    def getterName(name):
        return '_get_%s' % name

    def rawGetterName(name):
        return '_SO_get_%s' % name

    def instanceName(name):
        return '_SO_val_%s' % name

    ########################################
    # Utility functions (for external consumption)
    ########################################

    def getID(obj, refColumn=None):
        if isinstance(obj, SQLObject):
            return getattr(obj, refColumn or 'id')
        elif isinstance(obj, int):
            return obj
        elif isinstance(obj, long):
            return int(obj)
        elif isinstance(obj, str):
            try:
                return int(obj)
            except ValueError:
                return obj
        elif obj is None:
            return None

    def getObject(obj, klass):
        if isinstance(obj, int):
            return klass(obj)
        elif isinstance(obj, long):
            return klass(int(obj))
        elif isinstance(obj, str):
            return klass(int(obj))
        elif obj is None:
            return None
        else:
            return obj

    __all__ = [
        'NoDefault', 'SQLObject', 'SQLObjectIntegrityError', 'SQLObjectNotFound',
        'getID', 'getObject', 'sqlhub', 'sqlmeta',
    ]