# Database Wrapper

The Peewee database wrapper provides a thin layer of integration between flask apps and the peewee orm.

The database wrapper is important because it ensures that a database connection is created for every incoming request, and closed upon request completion. It also provides a subclass of `Model` which works with the database specified in your app’s configuration.

Most features of `flask-peewee` require a database wrapper, so you very likely always create one.

The database wrapper reads its configuration from the Flask application. The configuration requires only two arguments, but any additional arguments will be passed to the database driver when connecting:

name

  The name of the database to connect to (or filename if using sqlite3)

engine

  The database driver to use, must be a subclass of `peewee.Database`.

    from flask import Flask
    from peewee import *

    from flask_peewee.db import Database

    DATABASE = {
        'name': 'example.db',
        'engine': 'peewee.SqliteDatabase',
    }

    app = Flask(__name__)
    app.config.from_object(__name__)  # Load database configuration from module.

    # Instantiate the db wrapper.
    db = Database(app)

    # Start creating models.
    class Blog(db.Model):
        name = CharField()
        # .. etc.

You can also directly pass the Peewee database instance to the `Database` helper:

    app = Flask(__name__)
    app.config.from_object(__name__)

    sqlite_db = SqliteDatabase('example.db')
    db = Database(app, sqlite_db)

    class Blob(db.Model):
        # ...

The database initialization can be deferred in order to support more dynamic behavior:

    from flask_peewee.db import Database

    # Defer initialization but define our models.
    db = Database()

    class Blog(db.Model):
        name = CharField()
        # .. etc.

    # Some time later, we can:
    app = Flask(__name__)
    app.config.from_object(__name__)
    db.init_app(app)

    # Or we can also specify the database directly.
    app = Flask(__name__)

    sqlite_db = SqliteDatabase('example.db')
    db.init_app(app, sqlite_db)

## Other examples

To connect to MySQL using authentication:

    DATABASE = {
        'name': 'my_database',
        'engine': 'peewee.MySQLDatabase',
        'user': 'db_user',
        'passwd': 'secret password',
    }

To connect to Postgresql using the playhouse `PostgresqlExtDatabase`:

    DATABASE = {
        'name': 'pg_database',
        'engine': 'playhouse.PostgresqlExtDatabase',
        'host': '127.0.0.1',
        'user': 'postgres',
        'port': 5432,
    }

We can specify the database directly, as well:

    pg_db = PostgresqlDatabase('pg_database')

    db = Database(app, pg_db)