Flask SqlAlchemy : Records not displayed

Question

Here is my code :

from flask import Flask
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from database_setup import Base, Restaurant, MenuItem

app = Flask(__name__)

engine = create_engine('sqlite:///restaurantmenu.db')
Base.metadata.bind = engine

DBSession = sessionmaker(bind=engine)
session = DBSession()


@app.route('/')
@app.route('/restaurants/<int:restaurant_id>/')
def restaurantMenu(restaurant_id):
    restaurant = session.query(Restaurant).filter_by(id=restaurant_id).one()
    items = session.query(MenuItem).filter_by(restaurant_id=restaurant.id)
    output = ''
    for i in items:
        output += i.name
        output += '</br>'
        output += i.price
        output += '</br>'
        output += i.description
        output += '</br>'
        output += '</br>'
    return output

if __name__ == '__main__':
    app.debug = True
    app.run(host='0.0.0.0', port=5000)

I run the file by entering the following URL :

localhost:5000/restaurants/2

And all I get is a blank page. I don't get any kind of error in my GitBash or browser or anywhere else.

I ran this simple code :

from flask import Flask
app = Flask(__name__)


@app.route('/')
@app.route('/hello')
def HelloWorld():
    return "Hello World"

if __name__ == '__main__':
    app.debug = True
    app.run(host='0.0.0.0', port=5000)

And this runs perfectly. What wrong am I doing ?

EDIT : 1

Tried to debug the code and noticed that the code doesn't enter the for i in items: loop.

@app.route('/')
@app.route('/hello')
def restaurantMenu():
    restaurant = session.query(Restaurant).first()
    items = session.query(MenuItem).filter_by(restaurant_id = restaurant.id)
    output = ''
    print restaurant.name
    print restaurant.id

    if not items :
        print "No menu items!"
    else:
        print "There are menu items!"
        for i in items:
            print "In items loop!"
            output += i.name
            output += '<br>'
    return output + "Hello"

Have you setup your database so that there are actually records returned? As your code is written, an empty response is a perfectly valid response if no records are retrieved. — sholsapp
– sholsapp, Commented Jan 30, 2016 at 6:01
@sholsapp : Please see the screen capture i have added of the gitbash.. for what am i getting a 404 ? — Abhishek Ghosh
– Abhishek Ghosh, Commented Jan 30, 2016 at 6:09

Ja8zyjits · Accepted Answer · 2016-01-30 07:14:39Z

1

Basically you need the all() function at your items. You are querying properly but you are not fetching the results.

so your code will be like this

@app.route('/')
@app.route('/restaurants/<int:restaurant_id>/')
def restaurantMenu(restaurant_id):
    restaurant = session.query(Restaurant).filter_by(id=restaurant_id).one()
    items = session.query(MenuItem).filter_by(restaurant_id=restaurant.id).all()
    output = ''
    for i in items:
        output += i.name
        output += '</br>'
        output += i.price
        output += '</br>'
        output += i.description
        output += '</br>'
        output += '</br>'
    return output

if __name__ == '__main__':
    app.debug = True
    app.run(host='0.0.0.0', port=5000)

Now it will depend on the entries in your db, if you have any or else it will return an empty []. So if you have the results, you can print and check or loop and render it to your templates.

This should fix your issue

answered Jan 30, 2016 at 7:14

Ja8zyjits

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6 Comments

Abhishek Ghosh Over a year ago

Yes that did the trick. But suddenly i realize that the list is empty! I would be grateful if you see this code. I used this script to insert menu items : pastebin.com/e2XUruJi

Ja8zyjits Over a year ago

@AbhishekGhosh I shall look into it, but that will be another question, right? Please accept this if it solves the problem for which you posted initially. :)

Abhishek Ghosh Over a year ago

I accepted your answer! If you could now just look into the script... I will ask another question then!

Ja8zyjits Over a year ago

@AbhishekGhosh that will be the proper way to do it in here. One small advise use session.commit() at the end of all the add and if possible use a csv, that shall be a better way to do it instead of writing all entries.

Abhishek Ghosh Over a year ago

I am pursuing an online course from Udacity. They had provided me with this file! That is why I used it. Anyways, thanks!

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