Use a valid filter() for userId Datastore query

[dbs]

The code for the solution for the Datastore query that is supposed to return only a specific user's books fails to return any books. The problem is that the comparison operator and property key were included in a single string. Break the values out into separate strings so that the filter() method has a property, comparison operator, and value as expected.

Closes #69.

Signed-off-by: Dan Scott [email protected]

[googlebot]

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[dbs]

I'm Dan Scott, and I confirm that I did author this commit.