[Resolved] issues with the WPGraphQL plugin

I attached the debug information as requested for my local test site. However, I don't think you will need it, as I managed to reproduce the issue on the testing environment that you provided. Below is a description of what I did.

I installed the following plugins:
Classic Editor
ACF Pro
ACFML
WPGraphQL
WPGraphQL for ACF
WPGraphQL WPML

I set up WPML with English as the base language and Dutch as the only translation.

I created one ACF group called "Test group", which has one field "Test relationship". This group is shown on pages, and the relationship allows selecting one or more posts (only of the default "post" post type).

I created two posts "Test post" and "Test post 2" with only a title. I translated them to Dutch using the WPML Translation Editor, adding "(NL)" at the end of the translated title to better distinguish between languages.

I created two test pages "Test page" and "Test page 2".

On the first test page, I selected "Test post" as the only relationship, and translated the page using the WPML Translation editor, again adding "(NL)" at the end of the translated page title. Upon checking the English translation, I noticed that the relationship copied, but it hadn't selected the translated version of the relationship post. Instead, the English version (without "(NL)" in the title) was shown. Important to notice is that it is currently saved as a serialized array, and I can query it in WPGraphQL. I then re-saved the English page to trigger a translation update. Afterwards, the correct (translated) post was selected on the Dutch version of the post. However, the WPGraphQL no longer returns a post, because it is now saved as a single ID (in PHPMyAdmin, see the

wp_postmeta

table, and search for post ID 59).

This query can be ran in the integrated GraphiQL IDE on the test site, to show that the related post cannot be found by WPGraphQL because it is saved as a numeric ID instead of a serialized array:

query NewQuery {
  page(id: "59", idType:DATABASE_ID) {
    databaseId
    title
    locale {
      locale
    }
    testGroup {
      testRelationship {
        ... on Post {
          databaseId
          title
          locale {
            locale
          }
        }
      }
    }
  }
}

To show the difference between the once-translated and re-translated outputs, I created a second test page. On this page, I repeated the same steps as the first test page, but I stopped after translating it to Dutch once. On the PHPMyAdmin, if you look at the

wp_postmeta

table, and search for post ID 63 (the translated version of the second page), you will see a serialized array with a single element, which is the post ID 54. This is the ID of the English version of the second test post.

The code below is a query you can use to test the GraphQL output for the second page.

query NewQuery {
  page(id: "63", idType:DATABASE_ID) {
    databaseId
    title
    locale {
      locale
    }
    testGroup {
      testRelationship {
        ... on Post {
          databaseId
          title
          locale {
            locale
          }
        }
      }
    }
  }
}

I hope this clearly shows the situation, and will help you debug the ACFML plugin. To summarize what I think goes wrong here:

When an ACF relationship field (set to expert mode, copy) is initially translated, the exact contents of the original post are copied to the new post. This means the new post will have a relationship to the untranslated related post, but it will be correctly saved as a serialized array (because the contents are simply copy-pasted).

When updating the translation for an existing post, the translation step for the ACF relationship field works differently. The translated version(s) of the related post(s) is/are found, and then saved to the translated post, but if there is only one related post, the value is never converted to an array before saving, hence saving it as a single numeric ID, instead of a serialized array with a single value.

Hi Subash,

Sorry for the radio silence. I've had some other issues on my plate. I tried the fix just after posting my last message, but it unfortunately did not solve the issue for me.

I'll be looking forward to seeing the official fix.