Google App Engine: IN filter and argument position

Question

I have a table where one of the columns contains a list. I want to know if it is possible to select all rows where the list contains a specific element.

More concretely, I have a guests column containing a list of strings and I want to know if a specific guest string is part of this list. I would like to write a query like this:

q = TableName.gql('WHERE :g IN guests', g=guest)

It seems, however, that I can't put variables in this position. For instance, this query (where ownerid is a string and not a string list) is also disallowed:

q = TableName.gql('WHERE :g = ownerid', g=guest)

I seem to have to write it this way:

q = TableName.gql('WHERE ownerid = :g', g=guest)

Thus I have the following questions:

1. How can I construct a query that gets rows where a list-cell contains a specific member?
2. Are arguments for GQL queries restricted to the right-hand side of operators? What is the restriction?

I am using Google App Engine with Python 2.7. Thanks!

Answer 1

You have misunderstood what the IN operator is for. It is not for querying against a repeated field: you just use the normal = for that. IN is for querying against a list of values: eg guest IN [1, 2, 3, 4]. Your query should be:

q = TableName.gql('WHERE guests = :g', g=guest)

or better, since GQL doesn't give you anything that the standard DB syntax doesn't:

q = TableName.all().filter('guests =', guest)