GraphQL SPQR - How to get the list of the fields were requested by client using a query

Question

is there a way to retrieve the list of the fields were requested in a GraphQL query by a client?

Lets assume I have the following types:

type Book {

  isbn: String
  title: String
  genre: String
  author: Author
}

type Author {

  name: String
  surname: String
  age: Int
}

Is there a way on Java side inside a method annotated with @GraphQLQuery to know the fields were requested by the client?

For example, having the following queries:

query {

  book ( isbn = "12345" ) {
  
    title
    genre
  }
}

query {

  book ( isbn = "12345" ) {
  
    title
    author {
    
      name
      surname
    }
  }
}

I can know the first query requested the fields title and genre of Book and the second required title from Book and also name and surname of the Author ?

Thanks Massimo

Answer 1

You can obtain this info via @GraphQLEnvironment. If you just need the immediate subfields, you can inject the names like this:

@GraphQLQuery
public Book book(String isbn, @GraphQLEnvironment Set<String> subfields) {
    ...
}

If you want all the subfields, or other selection info, you can inject ResolutionEnvironment and get DataFetcherEnvironment from there. That in turn gives you access to the whole SelectionSet.

@GraphQLQuery
public Book book(String isbn, @GraphQLEnvironment ResolutionEnvironment env) {
    DataFetchingFieldSelectionSet selection = env.dataFetchingEnvironment.getSelectionSet();
     ...
}