Support `in` query filter

[enzo-crance-statnett]

Hello.

On one of our React-Admin pages, we have to filter a list on an enum field, keeping only rows whose value for this field is in a subset selected by the user in a CheckboxGroupInput component :

<CheckboxGroupInput
  label="Enumfield"
  source="enumfield@in"
  choices={[
    { id: "a", name: "A" },
    { id: "b", name: "B" },
    { id: "c", name: "C" },
  ]}
/>

The source property here is expressed in the syntax expected by this library, so the in query filter type is correctly translated into enumfield=in. in the query to be sent to the server.

However, the filter value coming from the input component is an array of strings (e.g., ["a", "c"] if only boxes A and C are checked), and it looks like there is no support for that in this library. Indeed, what we get in the final URL filter is enumfield=in.a,c whereas it should be enumfield=in.(a,c) according to the PostgREST syntax. Could you please confirm that ?

If you are open to contributions, we could propose a fix by adding a case for the in query filter type in the parseFilters function in urlBuilder.ts, if that makes sense.

Thanks for your help.

[scheiblr]

Hey @enzo-crance-statnett. Excuse my late reaction, I was currently very busy. You could have a look at the test cases, which might give you some insight, which functionality should already work and is implemented in the current state. In my opinion that would also be the fist step, i.e. creating test cases for you idea. Genrally, I like the approach of implementing the in for the filter. And I am very happy about contributions - thank you for the offer. Feel free to extend the library. That is the idea of making tools as such OS :)