searchableAttributes relations are not updated after removal

[20x-dz]

Description The content of deleted relations that are being used as searchableAttributes are still kept in the index.

Assume the following model (simplified):

Department = {
  title: text
}

To be able to expand the search results I created a SearchSynonm model with a n:m relationship with Department (and other models).

SearchSynonym = {
  text: text,
  "departments": {
    "type": "relation",
    "relation": "manyToMany",
    "target": "api::department.department",
    "inversedBy": "search_synonyms"
  }
}

Department = {
  title: text,
  search_synonyms: {
     "type": "relation",
     "relation": "manyToMany",
     "target": "api::search-synonym.search-synonym",
     "mappedBy": "departments"
  }
}

Searching for a department with a previously created and attached searchSynonym works just fine with the following setting (simplified):

          searchableAttributes: [
            "title",
            "search_synonyms.text",
          ],

But when I remove a synonym from a department the department is still indexed via the previously removed synonym, although the updated entry does not contain any information about the previous relationship (debugged via transformEntry).

I was able to bypass this issue by creating a dynamic attribute in transformEntry (but I think it should also work by using the relationship data directly):

transformEntry({ entry }) {
  const department = {
    ...entry,
    synonyms: entry.search_synonyms.map(synonym => synonym.text)
  };

  return department;
},
settings: {
  searchableAttributes: [
    "title",
    "synonyms",
  ],
}

Updating the index through the strapi settings works as well.

Note: I am fully aware of #424, but this is a different issue, as the indexed model is not being updated accordingly when modified.

Assume the following query for the next two points:

{
  "queries": [
    {
      "indexUid": "department",
      "q": "wort"
    }
  ]
}

Expected behavior A search should not return entries that had a searchable relationship removed.

{
  "results": [
    {
      "indexUid": "department",
      "hits": [],
      "query": "wort",
      "processingTimeMs": 0,
      "limit": 20,
      "offset": 0,
      "estimatedTotalHits": 0
    }
  ]
}

Current behavior Data in the index is not being updated.

{
  "results": [
    {
      "indexUid": "department",
      "hits": [
        {
          "title": "Chirurgie",
          "id": 180,
          "search_synonyms": []
        }
      ],
      "query": "wort",
      "processingTimeMs": 0,
      "limit": 20,
      "offset": 0,
      "estimatedTotalHits": 1
    }
  ]
}

Environment (please complete the following information):

• OS: macOS Ventura 13.6
• Meilisearch version: 1.3.5 (dockerized)
• strapi-plugin-meilisearch version: v0.9.2
• Browser: Chrome 118.0.5993.70, curl 8.1.2 (x86_64-apple-darwin22.0) libcurl/8.1.2 (SecureTransport) LibreSSL/3.3.6 zlib/1.2.11 nghttp2/1.51.0
• Strapi version: v4.13.7