graphql-tools merge behaviour repro

• checkout repository
• run yarn or npm i
• run node index.js
• browse to localhost:8484/api/graphql to open playground

This works

{
  book {
    id
    title
    author {
      id
      name
      books {
        id
        title
        author {
          id
          name
          books {
            id
            title
            author {
              name
            }
          }
        }
      }
    }
  }
}

This does not

{
  author {
    id
    name
    books {
      id
      title
      author {
        id
        name
        books {
          title
          author {
            name
          }
        }
      }
    }
  }
}

Possible Cause

https://github.com/apollographql/graphql-tools/blob/master/src/stitching/mergeSchemas.ts#L446

Because of the delegated resolver, the query for author does not return author.books, which are needed to resolve the book objects.

Possible Solution

• Ugly: Add bookIds to the Author type, but then we need to explicitly select bookIds in the query. We could inject transforms to the delegating resolver somehow to always fetch bookIds, but that just makes a simple task like this even more hideous.