Unable to make Flask-SQLAlchemy connect to my Google App Engine DB - google-app-engine

Question

I am trying to set up a web-application based on Flask using Google App Engine (I'm new to both).
The web-application receives data from the client and it should be processed and saved in a database.
I've tried to use Flask-SQLAlchemy but I'm unable to set it up with Google Cloud SQL, I've used this guide to create a MySQL DB in the same project:
and then I'm trying to use it on my main python code:
app.config('SQLALCHEMY_DATABASE_URI') = 'mysql+mysqldb://root#/Results?unix_socket=/cloudsql/crafty-circlet-164415:psy01'
app.config['SECRET_KEY'] = 'NglfxE8FOP9pgV8fxpyj'
db = SQLAlchemy(app)
class Result(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.Text)
profession = db.Column(db.Text)
year = db.Column(db.Text)
pressure_level = db.Column(db.Integer)
reported_suc_count = db.Column(db.Integer)
marked_suc_count = db.Column(db.Integer)
real_suc_count = db.Column(db.Integer)
insertion_time = db.Column(db.DateTime)
def __init__(self, name, profession, year, pressure_level, reported_suc_count, marked_suc_count, real_suc_count):
self.name = name
self.profession = profession
self.year = year
self.pressure_level = pressure_level
self.reported_suc_count = reported_suc_count
self.marked_suc_count = marked_suc_count
self.real_suc_count = real_suc_count
self.insertion_time = datetime.utcnow()
#app.route('/resultform', methods=['POST', 'GET'])
def resultform():
if request.method == 'POST':
if not request.form['successmatrices']:
flash('please fill all the fields', 'error')
else:
if 'name' in request.form:
name = request.form['name']
else:
name = None
if 'profession' in request.form:
profession = request.form['profession']
else:
profession = None
if 'year' in request.form:
year = request.form['year']
else:
year = None
if 'pressure_level' in request.form:
pressure_level = int(request.form['pressure_level'])
else:
pressure_level = None
if 'successmatrices' in request.form:
successmatrices = int(request.form['successmatrices'])
else:
successmatrices = 0
new_result = Result(name=name, profession=profession, year=year, pressure_level=pressure_level, reported_suc_count=successmatrices, marked_suc_count=len(session['marked']), real_suc_count=len(session['correct']))
db.session.add(new_result)
db.session.commit()
return redirect(url_for('showresults'))
return render_template("resultform.html")
#app.route('/showresults')
def showresults():
return render_template("showresults.html", results=Results.query.all())
if __name__ == '__main__':
db.create_all()
app.run(debug=True)
When I'm trying to run it in my local development (I'm using PyCharm) I receive the following error in the background:
ERROR 2017-04-16 09:20:19,802 wsgi.py:263]
Traceback (most recent call last):
File "C:\Users\<>\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\google\appengine\runtime\wsgi.py", line 240, in Handle
handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
File "C:\Users\<>\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\google\appengine\runtime\wsgi.py", line 299, in _LoadHandler
handler, path, err = LoadObject(self._handler)
File "C:\Users\<>\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\google\appengine\runtime\wsgi.py", line 85, in LoadObject
obj = __import__(path[0])
File "C:\Users\<>\PycharmProjects\crafty-circlet-164415\main.py", line 7
app.config('SQLALCHEMY_DATABASE_URI') = 'mysql+mysqldb://root#/Results?unix_socket=/cloudsql/crafty-circlet-164415:psy01'
SyntaxError: can't assign to function call
And after deployment to GAE the following error appears:
Error: Server Error
The server encountered an error and could not complete your request.
Please try again in 30 seconds.
Any idea how to solve this?

Answer 1

app.config is a dictionary, so to add a config value you'll use a [ ] instead of () just as done in you app.config['SECRET_KEY'].
So it should be:
app.config['SQLALCHEMY_DATABASE_URI'] = SQLALCHEMY_DATABASE_URI
Some other pointers too for a successful connection. You'll need to format your connection details properly:
USER = 'root'
PASSWORD = 'your-cloudsql-password'
DATABASE = 'your-cloudsql-database-name'
# connection_name is of the format `project:region:your-cloudsql-instance`
CONNECTION_NAME = 'your-cloudsql-connection-name'
SQLALCHEMY_DATABASE_URI = (
'mysql+pymysql://{user}:{password}#localhost/{database}'
'?unix_socket=/cloudsql/{connection_name}').format(
user=USER, password=PASSWORD,
database=DATABASE, connection_name=CONNECTION_NAME)
app.config['SQLALCHEMY_DATABASE_URI'] = SQLALCHEMY_DATABASE_URI
I'll probably separate my secrets and all other sensitive info into a config file not checked into source or use environment variables, etc.
If you want to locally test your application with your Cloud SQL instance, you'll need to install the Cloud SQL Proxy and add the connection name as an environment variable and the MySQLdb library to your app.yaml
> cloud_sql_proxy -instances=your-connection-name=tcp:3306
Else you can use a local MySQL instance for testing but switching to Cloud SQL when on app engine.
More information on setting up Cloud SQL with App Engine can be found here