Question Re: CAP Java: Handle $count query in Custom Handler in Technology Q&A

CAP Java: Handle $count query in Custom Handler

christoffer_fuss — Wed, 11 Oct 2023 05:41:16 GMT

Hello community,

we are using CAP Java and want to use the $count query in a custom handler:

Query:
http://localhost:8080/api/play/Books/$count

We are using the CqnAnalyzer to check if this is a $count query or not. Normally we return a list of Books but we don't know, how we can return the response for a $count query.

If we return the List of Books as well we are getting the error:

So what is the correct way to return the result for $count?
In the documentation I just found how to pass the inlinecount by using the ResultBuilder.

Result r = selectedRows(asList(row)).inlineCount(inlineCount).result();

Best regards and many thanks,
Chris

Re: CAP Java: Handle $count query in Custom Handler

robinjayasinghe — Wed, 11 Oct 2023 06:41:34 GMT

It seems that the formatting of the code block of your handler is lost. Could you please edit the post? Thx! 🙂

Re: CAP Java: Handle $count query in Custom Handler

christoffer_fuss — Wed, 11 Oct 2023 07:18:16 GMT

Sry for that but posting code seems to be broken, so I used a picture instead.

Best regards,

Chris

Re: CAP Java: Handle $count query in Custom Handler

marcbecker — Wed, 11 Oct 2023 07:27:37 GMT

The $count query from OData is done by sending a CqnSelect containing only a count(*) function with alias count. Therefore the expected result structure would be something like this:

Arrays.asList(Collections.singletonMap("count", value));

You can adapt your method signature to use return type List<Map<String, Object>>

Re: CAP Java: Handle $count query in Custom Handler

christoffer_fuss — Wed, 11 Oct 2023 11:35:26 GMT

Thanks Marc, it works fine 🙂 Maybe you can add this in the documentation as well.

Best regards,

Chris

Re: CAP Java: Handle $count query in Custom Handler

marcbecker — Mon, 23 Oct 2023 14:22:36 GMT

I opened a PR to improve this in our docs: https://github.com/cap-js/docs/pull/495