How to use PyMongo with Flask Blueprints?

Question

What is the correct way of picking up mongo object inside Blueprints?

Here is how I have my parent login.py:

app.config.from_object(\         


        

Answer 1

You're are initializing the PyMongo driver twice, once in child.py and a second time on child2.py.

Try initializing the PyMongo connection in the file which sets up your app object and then import it in the children:

login.py:

app.config.from_object('config')
from flask.ext.pymongo import PyMongo
from child import child
from child2 import child2


app = Flask(__name__)
mongo = PyMongo(app)

# Register blueprints
def register_blueprints(app):
    # Prevents circular imports
    app.register_blueprint(child2.child2)
    app.register_blueprint(child.child)

register_blueprints(app)

in child.py

from app import app, mongo

child = Blueprint('child', __name__)

child2.py:

from app import app, mongo

child2 = Blueprint('child2', __name__)

Answer 2

One of the issues with the approach of performing an import in the blueprint as was suggest by Emanuel Ey, turns out that it causes a circular import. After much playing, it turns out that the only way (I could find) was to create a separate file called database.py that connects to the database and then I can import this connection to by blueprint as follows:

child.py

from database import mongo
courses = Blueprint('courses', __name__)

and my database.py

from flask.ext.pymongo import PyMongo
mongo = PyMongo() 

and the app, login.py but has to initialize the database

from database import mongo
app = Flask(__name__)
app.config.from_object('config')
mongo.init_app(app) # initialize here!

from child import child 
from child import2 child2

app.register_blueprint(child.child)
app.register_blueprint(child2.child2)