Flask app keeps returning error 500

Question

I have been learning how to use the Flask framework using a tutorial, but the code in my app.py keeps returning an error 500, and I can't figure out why (my code is identical to the tutorial).

Here's the app.py:

from flask import Flask, render_template, json, request
from flask.ext.mysql import MySQL
from werkzeug import generate_password_hash, check_password_hash

mysql = MySQL()
app = Flask(__name__)

# MySQL configurations
app.config['MYSQL_DATABASE_USER'] = 'root'
app.config['MYSQL_DATABASE_PASSWORD'] = 'root'
app.config['MYSQL_DATABASE_DB'] = 'BucketList'
app.config['MYSQL_DATABASE_HOST'] = 'localhost'
mysql.init_app(app)


@app.route('/')
def main():
    return render_template('index.html')

@app.route('/showSignUp')
def showSignUp():
    return render_template('signup.html')


@app.route('/signUp',methods=['POST','GET'])
def signUp():
    try:
        _name = request.form['inputName']
        _email = request.form['inputEmail']
        _password = request.form['inputPassword']

        # validate the received values
        if _name and _email and _password:

            # All Good, let's call MySQL

            conn = mysql.connect()
            cursor = conn.cursor()
            _hashed_password = generate_password_hash(_password)
            cursor.callproc('sp_createUser',(_name,_email,_hashed_password))
            data = cursor.fetchall()

            if len(data) is 0:
                conn.commit()
                return json.dumps({'message':'User created successfully !'})
            else:
                return json.dumps({'error':str(data[0])})
        else:
            return json.dumps({'html':'<span>Enter the required fields</span>'})

    except Exception as e:
        return json.dumps({'error':str(e)})
        return traceback.format_exc()
    finally:
        cursor.close() 
        conn.close()

if __name__ == "__main__":
    app.run(port=5002)

It's for a signup system.

Adding `app.debug = True` in the `if` block before `app.run` will give you more information. — mr nick, Sep 25 '15 at 23:18

score 1 · Answer 1 · answered Sep 25 '15 at 23:16

1

a 500 error usually means there is an error in your python instead when you run try it withh app.run(port=5002,debug=True) this wont solve your problem ... but it should tell you whats going on

answered Sep 25 '15 at 23:16

Joran Beasley

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score 1 · Answer 2 · answered Mar 23 '16 at 23:36

I know you are following this tutorial, because I am having the same problem - http://code.tutsplus.com/tutorials/creating-a-web-app-from-scratch-using-python-flask-and-mysql--cms-22972

The issue is that inside the stored procedure they are having you set a column of size 20:

CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_createUser`(
    IN p_name VARCHAR(20),
    IN p_username VARCHAR(20),
    IN p_password VARCHAR(20)
)

But when they tell you to salt the password in your python code, like you do:

_hashed_password = generate_password_hash(_password)

You are creating a string much longer than 20 characters, so if you ran this in debug mode you'd see the error says invalid column length for column password. I fixed this by just changing the size of the column to 100. :)

score 0 · Answer 3 · answered Feb 10 '17 at 16:45

I know this tutorial and I was getting the same error a couple of minutes back. I changed -

_hashed_password = generate_password_hash(_password)

to

_hashed_password = _password

and it worked! :).

I am assuming that the reason is size that we have declared for password field is less than what is actually needed if we hash. But for now, you can do the same and get the app running.

Happy Coding!

Flask app keeps returning error 500

3 Answers3