Support JSON:API filters

Discussion with @mglaman on Slack:

ptmkenny
  8 hours ago
Is it possible to use regular JSON:API filters (like /jsonapi/my-resource&filter[group-name][group][conjunction]=OR&filter[filter-name][condition][path]=n... on a JSON:API Resource created with the JSON:API Resources module?  It seems they are not supported out of the box, but is it possible to get filter support working, or do I have to add my own parameters to the resource to use instead of filters?

mglaman
  7 hours ago
I thought it’d work, as we expand filters like normal


mglaman
  5 hours ago
I guess I’m wrong, we don’t provide methods for this


mglaman
  5 hours ago
it was added in jsonapi_search_api but these helper methods should be applied in jsonapi_resources https://git.drupalcode.org/project/jsonapi_search_api/-/blob/8.x-1.x/src/Resource/IndexResource.php?ref_type=heads#L159-176


mglaman
  5 hours ago
https://git.drupalcode.org/project/jsonapi_search_api/-/blob/8.x-1.x/src/Resource/IndexResource.php?ref_type=heads#L190-197


mglaman
  5 hours ago
https://git.drupalcode.org/project/jsonapi_search_api/-/blob/8.x-1.x/src/Resource/IndexResource.php?ref_type=heads#L208-212

I started on an MR for this.

First, you need to add the following code to the process() method of your custom JSON:API resource:

    if ($request->query->has(Filter::KEY_NAME)) {
      $this->applyFiltersToQuery($request, $entity_query, $cacheability);
    }

    if ($request->query->has('sort')) {
      $this->applySortingToQuery($request, $entity_query, $cacheability);
    }

However, the filters don't currently work because I don't understand how to get the resource type (see the comment in the MR code).

An important note for filtering: the order of _jsonapi_resource_types in mymodule.routing.yml is important.

    _jsonapi_resource_types:
      ['node--base_for_entity_query', 'other_entity--bundle_type']

The first entity type listed must be the base for the entity query; if you put them in a random order, filters like entity_reference_field.referenced_entity_field will fail.