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# SQLObject and Python 3

Contents

- Changes between Python 2 and Python 3
  - BLOBCol
  - StringCol
  - UnicodeCol
- Python 3 and MySQL
- Using databases created with SQLObject and Python 2 in Python 3
  - SQLite
  - Postgres
  - MySQL

# Changes between Python 2 and Python 3

There are a few changes in the behaviour of SQLObject on Python 3, due to the changed stings / bytes handling introduced in Python 3.0.

## BLOBCol

In Python 3, BLOBCol now accepts and returns bytes, rather than strings as it did in Python 2.

## StringCol

In Python 3, StringCol now accepts arbitrary Unicode strings.

## UnicodeCol

The dbEncoding parameter to UnicodeCol has no effect in Python 3 code. This is now handled by the underlying database layer and is no longer exposed via SQLObject. The parameter is still available for those writing Python 2 compatible code.

# Python 3 and MySQL

SQLObject is tested using mysqlclient as the database driver on Python 3. Note that the default encoding of MySQL databases is latin1, which can cause problems with general Unicode strings. We recommend specifying the character set as utf8 when using MySQL to protect against these issues.

# Using databases created with SQLObject and Python 2 in Python 3

For most cases, things should just work as before. The only issues should around UnicodeCol, as how this is handled has changed.

## SQLite

The Python 3 sqlite driver expects Unicode columns to be encoded using utf8. Columns created using the default encoding on Python 2 should work fine, but columns created with a different encoding set using the dbEncoding parameter may cause problems.

## Postgres

Postgres' behaviour is similar to sqlite. Columns created using the default encoding on Python 2 should work fine, but columns created with a different encoding set using the dbEncoding may cause problems.

## MySQL

For MySQL, the results depend on whether the Python 2 database was using MySQLdb's Unicode mode or not.

If a character set was specified for the database using the charset parameter, such as:

    mysql:///localhost/test?charset=latin1

Things should work provided the same character set is specified when using Python 3.

If a character set wasn't specified, then things may work if the character set is set to match the dbEncoding parameter used when defining the UnicodeCol.