Connecting to google cloud SQL Error using Flask-SQLAlchemy

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.

kurtisvg · Accepted Answer · 2021-08-27 15:14:05Z

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.

answered Aug 27, 2021 at 15:14

kurtisvg

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2 Comments

Hikm Nasir Over a year ago

Thank you @kurtisvg for your answer, but I got a new error: "Instance of 'URL' has no 'render_as_string' member"

kurtisvg Over a year ago

@HikmahDwiyantiNasir - Perhaps make sure you are on a recent version - it's listed in the SQLAlchemy documentation here: docs.sqlalchemy.org/en/14/core/…

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