flask-admin different view for multiple databases - flask

Question

I have two different databases. They are: stock and commodity. Each database has two tables as follows:
Stock: User_trade_stock, stock_prices
Commodity: User_trade_commodity, commodity_prices
I try to build a web app to handle two databases with flask. When I apply flask-admin to them as follows
admin.add_view(UserView(User_trade_stock, db.session))
admin.add_view(UserView(User_trade_commodity, db.session))
I gives the following eror:
Assertion Error: A name collision occurred between blueprints. Blueprints that are created on the fly need unique name.
I tried to add the bind to the db.session as follows
admin.add_view(UserView(User_trade_stock, db.session(bind='stock_bind')))
admin.add_view(UserView(User_trade_commodity, db.session='commodity_bind')))
I got the following error:
scoped session is already present; no new arguments may be specified
Any helps would be appreciated

Answer 1

There are a couple of issues.
Flask-Admin uses a view's lower cased class name for the automatically generated Blueprint name. As you are using UserView twice you have a Blueprint name collision. To overcome this you can specify an endpoint name when you instance a view, for example:
admin = Admin(app, template_mode="bootstrap3")
admin.add_view(TestView(StockTest, db.session, category='Stock', name='Test', endpoint='stock-test'))
admin.add_view(TestView(CommodityTest, db.session, category='Commodity', name='Test', endpoint='commodity-test'))
and to get the urls of the views you would use the following code:
url_for('stock-test.index')
url_for('stock-test.edit')
url_for('commodity-test.index')
url_for('commodity-test.edit')
Secondly, if you want to use the bind feature of Flask-Sqlalchemy you should use the __bind_key__ attribute on the table model, for example:
class User(db.Model):
__bind_key__ = 'users'
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(80), unique=True)
Here is a single file example illustrating both concepts. You will need to run the flask commands flask create-databases and flask populate-databases before you use the app itself. Note I've used a mixin class, TestMixin, to define the model columns.
import click
from flask import Flask
from flask.cli import with_appcontext
from flask_sqlalchemy import SQLAlchemy
from flask_admin import Admin
from flask_admin.contrib.sqla import ModelView
from faker import Faker
from sqlalchemy import Integer, Column, Text
db = SQLAlchemy()
app = Flask(__name__)
app.config['SECRET_KEY'] = '123456790'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = True
app.config['SQLALCHEMY_BINDS'] = {
'stock': 'sqlite:///stock.db',
'commodity': 'sqlite:///commodity.db'
}
db.init_app(app)
class TestMixin(object):
id = Column(Integer, primary_key=True)
name = Column(Text(), unique=True, nullable=False)
class StockTest(db.Model, TestMixin):
__bind_key__ = 'stock'
class CommodityTest(db.Model, TestMixin):
__bind_key__ = 'commodity'
#click.command('create-databases')
#with_appcontext
def create_databases():
db.drop_all(bind=['stock', 'commodity'])
db.create_all(bind=['stock', 'commodity'])
#click.command('populate-databases')
#with_appcontext
def populate_databases():
_faker = Faker()
db.session.bulk_insert_mappings(StockTest, [{'name': _faker.name()} for _ in range(100)])
db.session.bulk_insert_mappings(CommodityTest, [{'name': _faker.name()} for _ in range(100)])
db.session.commit()
class TestView(ModelView):
pass
app.cli.add_command(create_databases)
app.cli.add_command(populate_databases)
admin = Admin(app, template_mode="bootstrap3")
admin.add_view(TestView(StockTest, db.session, category='Stock', name='Test', endpoint='stock-test'))
admin.add_view(TestView(CommodityTest, db.session, category='Commodity', name='Test', endpoint='commodity-test'))
#app.route('/')
def index():
return 'Click me to get to Admin!'
if __name__ == '__main__':
app.run()