How to look for a substring GQL?

Question

I'm trying to stop duplicates of a database entity called "Post" in my program. In order to do this I want to append a number like "1" or "2" next to it. In other words:

helloworld helloworld1 helloworld2

In order to do this I need to query the database for postid's starting with helloworld. I read that GQL doesn't support the LIKE operation, so what can I do instead?

Thanks!

Every datastore entity has an unique key. So what is the problem? If you do not assign a key yousef, the datastore will provide one (id). — voscausa, Apr 14 '14 at 23:06

score 0 · Answer 1 · answered Apr 14 '14 at 22:30

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Could you make the number a separate field? Then you won't have to search for prefix.

answered Apr 14 '14 at 22:30

Isaac

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Yes, but on what condition would I increment the number? – user2200321 Apr 14 '14 at 22:47
You could use a [Counter](https://developers.google.com/appengine/articles/sharding_counters) or encode both fields into the key and query for highest entry. – Isaac Apr 16 '14 at 21:25

score 0 · Answer 2 · answered Apr 14 '14 at 23:04

There is no LIKE.

Based on your criteria the closest you can achieve will be a query using the '>' and '<' operators.

select * from Post where postid > "helloworld" and postid < "helloworld9999" for instance.

I don't really understand what you are trying to do, so there may well be a better approach, maybe you can elaborate your use case.

How to look for a substring GQL?

2 Answers2