CODEWITHSUNDEEP
google-app-enginegoogle-cloud-endpointsgoogle-cloud-datastore
Micro
Micro

Reputation: 10891

Cloud Endpoints calculated an Entity property at query time

How can I have a property in an Entity be calculated at query time?

For example if I had a Post Entity and I did getPost(Long postId), I would like the myPost.likes property to be calculated at that moment by getting a count of how many Like Entities there are with the specific Post key.

OR

If this is not possible, I was considering storing a Int likes property for each Post Entity that I simply increment by one every time a new Like is inserted.

Upvotes: 0

Views: 50

Answers (1)

konqi
konqi

Reputation: 5227

Both would work. For the latter i would use sharding counters if you expect many lps (likes per second). I would use the first approach though since then a like can have meta like, when it was created, by whom, etc.

There's no real at query time calculation for that. You would have to write the query to sum up the likes yourself. In Objectify you could use the @OnLoad annotation to query it for each post, after a query. I strongly recommend that you don't do that though since that would be a query for each returned Post of a query. You really should do that manually to avoid redundant queries for likes when you don't even need them.

Upvotes: 1

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