BUG: FlaskDB incorrect implementation

1. current implementation of FlaskDB https://github.com/coleifer/peewee/blob/master/playhouse/flask_utils.py#L87 is incorrect: it stores database in self instead of the flask context

2. that prevents FlaskDB to be used with flask factory pattern for tests with multiple flask app instances using different per-app-instance database configurations created inside single python process

3. see: https://flask.palletsprojects.com/en/1.1.x/patterns/appfactories/#factories-extensions https://flask.palletsprojects.com/en/1.1.x/extensiondev/#the-extension-code

[Andrei-Pozolotin]

even more simplified example:

import peewee
from flask import Flask, current_app
from playhouse.sqlite_ext import SqliteExtDatabase

class PeeweeDatawrap:

    def init_app(self, app:Flask) -> None:
        app.extensions['peewee_database'] = self.produce_database(app)
        app.before_request(self.perform_open)
        app.teardown_request(self.perform_close)

    def perform_open(self, *args, **kwargs) -> None:
        self.database.connect()

    def perform_close(self, *args, **kwargs) -> None:
        self.database.close()

    def produce_database(self, app:Flask) -> peewee.Database:
        datafile = app.config['DATABASE']
        return SqliteExtDatabase(datafile)

    @property
    def database(self) -> peewee.Database:
        return current_app.extensions['peewee_database']

[Andrei-Pozolotin]

1. well, we do not want to follow low standards, do we? 😃

2. on another note, this pattern is also a major pain:

class Model:
   class Meta:
      database: ...

1. perhaps switching peewee default database injection to flask-like current_app analogue would be less evil