Posts with Related Posts of the same content type produce very deep object

Expected Behavior

When fetching post data with include: 3, response should not return data deeper than 3 levels.

Actual Behavior

export async function getPosts(slug, preview) {
  const entries = await contentfulClient(preview).getEntries({
    content_type: 'post',
    'fields.slug[in]': slug,
    include: 3
  });

  return entries;
}

The following returns:

 items: {
    0: {
      fields: {
        title: 'article 1',
        relatedPosts: {
          0: {
            fields: {
              title: 'article 2',
              relatedPosts: {
                0: {
                  fields: {
                    title: 'article 3',
                    relatedPosts: {
                      0: {
                        fields: {
                          title: 'article 4',
                          relatedPosts: [...goes on very deep...]
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }

• Node Version: 14.13.1
• Yarn Version: 1.22.10
• Operating System: OSX Chrome
• Package Version: 7.14.8
• Which API are you using?: Delivery

[TimBeyer]

Hi @AlexandraKlein could it be that the relatedPosts contain circular references?
While include: 3 only fetches three levels deep, if entries reference each other, they are linked together so a circular reference might look like infinite depths when logged.

[TimBeyer]

From the thread it sounds like we can close the issue, correct?
Sadly there isn’t really a way to stop circular dependencies after a certain level.
The entry objects that link to each other are always the same instances, so there is no way to break the cycle at some point.

Take for example a list of objects linking like this A -> B -> C -> A -> B ....
The instance of A that links to B is the same as the one C links to.
If I were to remove the reference from A to B to break the cycle at the point where it repeats, I would break the original chain too.

If you want to work with a fully flattened version of the model, you would have to use the raw response and manually resolve the includes from the returned entries where you can keep track of cycles yourself.