CODEWITHSUNDEEP
pythongoogle-app-enginegql
electron1
electron1

Reputation: 97

What does a GQL Query Return

I have been working on a project using Google App Engine. I have been setting up users and have to check if a username is taken yet.
I used the following code to try to test whether it is taken or not 

usernames = db.GqlQuery('select username from User') 
taken = username in usernames

This never caught duplicate usernames. I tried a few variants of this on the GQL query line. I tried using .get() which caused an error because it returned something that wasn't iterable. I also tried putting list() around the request, which returned the same error. I tried writing the value of usernames but never got any response. If it returns a query instance, then is there any way to turn it into a list or tuple?

Upvotes: 0

Views: 185

Answers (1)

Tim Hoffman
Tim Hoffman

Reputation: 12986

For starters you should revisit the docs https://cloud.google.com/appengine/docs/python/datastore/gqlqueryclass?hl=en

db.GqlQuery('select username from User') is calling a constructor not a function so it returns an instance of a GqlQuery object. See docs referred to above.

Secondly what you are doing will never work reliably due to eventual consistancy . Please read https://cloud.google.com/appengine/docs/python/datastore/structuring_for_strong_consistency to understand why.

Lastly you are starting out with appengine, so move away from db and use ndb unless you have a significant existing code base.

Upvotes: 1

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