Using Postgresql

To connect to a Postgresql database, we will use PostgresqlDatabase. The first parameter is always the name of the database, and after that you can specify arbitrary psycopg2 parameters.

psql_db = PostgresqlDatabase('my_database', user='postgres')
class BaseModel(Model):
    """A base model that will use our Postgresql database"""
    class Meta:
        database = psql_db
class User(BaseModel):
    username = CharField()

The Playhouse, extensions to Peewee contains a Postgresql extension module which provides many postgres-specific features such as:

• Arrays
• HStore
• JSON
• Server-side cursors
• And more!

If you would like to use these awesome features, use the PostgresqlExtDatabase from the playhouse.postgres_ext module:

from playhouse.postgres_ext import PostgresqlExtDatabase
psql_db = PostgresqlExtDatabase('my_database', user='postgres')

Isolation level

As of Peewee 3.9.7, the isolation level can be specified as an initialization parameter, using the symbolic constants in psycopg2.extensions:

from psycopg2.extensions import ISOLATION_LEVEL_SERIALIZABLE
db = PostgresqlDatabase('my_app', user='postgres', host='db-host',
                        isolation_level=ISOLATION_LEVEL_SERIALIZABLE)

Note

In older versions, you can manually set the isolation level on the underlying psycopg2 connection. This can be done in a one-off fashion:

db = PostgresqlDatabase(...)
conn = db.connection()  # returns current connection.
from psycopg2.extensions import ISOLATION_LEVEL_SERIALIZABLE
conn.set_isolation_level(ISOLATION_LEVEL_SERIALIZABLE)

To run this every time a connection is created, subclass and implement the _initialize_database() hook, which is designed for this purpose:

class SerializedPostgresqlDatabase(PostgresqlDatabase):
    def _initialize_connection(self, conn):
        conn.set_isolation_level(ISOLATION_LEVEL_SERIALIZABLE)