The string_long field type is not available to search_api for indexing.

Custom fields are properties on a field. Add the field first and you should see the custom fields (ie; properties) exposed as values to index. Please verify this and update ticket.

@apmsooner. Thank you for your tip! I just found there is a plus sign + before the custom fields, clicked to expand it, then the sub-fields (properties) appeared with plus signs, then I can add them seperately as below:

However. I cannot add text(long) and entity_reference sub-fields in a custom field to search_api index, as the screenshot below:

Hmm.. yeah the styling is really odd here. The text_long and entity_reference custom field types are actually custom data types also so something is weird i guess with what search_api is using for the source. I'll have to do some research.

The html is fixed in the related ticket. I've found a solution using event subscriber to get the unrecognized custom data types "recognized" by search api. I may not be able to immediately find solution for the entity reference relationship but I can at least get the string_long field types working. Patch will be available to test out shortly.

Providing a patch to get the string_long type recognized for indexing. I'll create another ticket to address the file, image and entity_reference field types as those are more complex to get relationship data and will need to research options.

Added sub-module to handle extended search api support. For now this is limited to extending the string_long custom field data type but will be the home for additional extension to handle entity_reference, image and file types in followup task(s).

@fishfree - the entity_reference, file and image custom field types will be handled in this issue: https://www.drupal.org/project/custom_field/issues/3470853 ✨ Search API: Support mapping/indexing referenced entity properties Needs review . Please follow that issue and help with testing when ready to review. I should have a patch up hopefully tomorrow if not sometime over the weekend.

@apmsooner Thank you! Now, the text_long sub-field works with your commit.

@fishfree - you can try the patch here for the nested entity properties: https://www.drupal.org/project/custom_field/issues/3470853 ✨ Search API: Support mapping/indexing referenced entity properties Needs review . Custom field types entity_reference, file and image are all supported.