A way to define custom filters

[HassanAzzam]

Currently can't define filters other than the defined in the filter expression visitor class.

It's nice to have custom filters such as subsetof or so, but can't find a clean way to do so.

[dpimonov]

Hi HassanAzzam, сould you please provide a more detailed example of your use case? The current implementation already supports complex filtering and serialization, but maybe I missed something. Thanks in advance!

[HassanAzzam]

Have a look at elide.io(a known json api library for Java), there is a list of supported operators for filtering out-of-box(supersetof is my current need). I was wondering if there is any way to inject implementation for these operators in the filter expression visitor class.

[dpimonov]

Got it! The filter expression visitor is a specific interface provided by the entity store. It can be tricky to create custom implementations because it involves a lot of reflection, filter expressions creation and delegation logic to keep things simple for the end user. Usually, you can achieve the same results as with supersetof using or/and filtering. But they do not provide them. The only way by design is to extend an entity store and implement new methods by concrete implementations. Also elide requires its own filter expression visitor on this side of the library.