Connecting to google cloud SQL Error using Flask-SQLAlchemy - flask

Question

I'm totally beginner for use flask and Google Cloud SQL. I want to make Login and Registration in my app using Flask-Login and Flask-SQLAlchemy.
But I can't connect to google cloud SQL using Flask-SQLAlchemy, this is my code.
SQLALCHEMY_DATABASE_URI = (
'mysql+pymysql://{db_user}:{db_password}#/{db_name}'
'?unix_socket=/cloudsql/{connection_name}').format(
user=db_user, password=db_password,
database=db_name, connection_name=connection_name)
app.config['SQLALCHEMY_DATABASE_URI'] = SQLALCHEMY_DATABASE_URI
I just got this error :
(2003, "Can't connect to MySQL server on 'localhost' ([Errno 2] No such file or directory)")
But, when I try to make a connection using SQLAlchemy with this code, the connection is succeeded :
query_string = dict({"unix_socket": "/cloudsql/{}".format(connection_name)})
driver_name = 'mysql+pymysql'
db = sqlalchemy.create_engine(
sqlalchemy.engine.url.URL(
drivername=driver_name,
username=db_user,
password=db_password,
database=db_name,
query=query_string),
pool_size=5,
max_overflow=2,
pool_timeout=30,
pool_recycle=1800)
But when I tried to change the code like this :
app.config['SQLALCHEMY_DATABASE_URI'] = db
then, I got this error: 'Engine' object has no attribute 'drivername'.
Any suggestion for this problem? any advice, might be very helpful for me, Thank you.

Answer 1

This line right here actually assigns the "engine" object to your URI config:
app.config['SQLALCHEMY_DATABASE_URI'] = db
You can use the url object to create a URI instead:
uri = sqlalchemy.engine.url.URL(
drivername=driver_name,
username=db_user,
password=db_password,
database=db_name,
query=query_string)
app.config['SQLALCHEMY_DATABASE_URI'] = uri.render_as_string(hide_password=false)
You can compare the URI to the one you created and see where they differ. It's likely there is a typo, or that some value is escaped incorrectly.