Show computed field in JSON:API output

I tried enabling the test_computed_field_output module and creating a computed field with each of its plugins. Same problem: they show up in the theme but not in JSON:API output.

That's weird, it should just work -- see 💬 Complete JSON:API's handling of field (including computed & empty fields) cache metadata Needs work , https://gorannikolovski.com/blog/add-computed-field-jsonapi-response

Can you debug?

Thanks @joachim. It does just work in 2.x & 3.x. Both those links you shared would be pre 4.x, no?

I downgraded back to 3.x to keep moving, but will revisit and dig further when time allows.

I could see the field listed in JSON:API Extras → ' Resource overrides pane for my entity (/admin/config/services/jsonapi/resource_types)... so it's being registered in some way.

> Thanks @joachim. It does just work in 2.x & 3.x. Both those links you shared would be pre 4.x, no?

They are for computed fields in general, independent of this module.

I’m experiencing the same issue. The field shows up everywhere except the JSON output.

Okay, it worked for me if I defined my computed field in code only (i.e. not adding the computed field to an entity bundle via the Field UI):

/**
 * Computed field string.
 *
 * @ComputedField(
 *   id = "computed_field_attached",
 *   label = @Translation("Computed field"),
 *   field_type = "string",
 *   no_ui = TRUE,
 *   attach = {
 *     "scope" = "base",
 *     "field_name" = "computed_field",
 *     "entity_types" = {
 *       "node" = {
 *         "article",
 *       },
 *     },
 *   },
 * )
 */

In that case, it it looks like this is a base field / bundle field problem.

I'm seeing the field in my jsonapi output, but it's only showing the first value. My computeValue method returns [1,2] but in the jsonapi I just see "1"