title: GraphQL merging data from multiple REST calls
body: <p>I have been looking at some <a href="https://graphql.org/" rel="nofollow noreferrer">GraphQL</a> implementations and what I understand is that GraphQL lets you traverse through the data in the form of a Graph.</p>
  
  <p>Which means you get a list of books which is a REST call. The books might have an Author Name.  </p>
  
  <p>When the user wants more info on an author he says so and another REST call is made to fetch more details about that author.</p>
  
  <p>Similarly the books list may have a field called Publisher and so on.
  So here you fetch data as if you are connecting a node of Book to a node of Author or Publisher.  </p>
  
  <p>But I have seen some implementations where data from two rest calls are combined using <code>for</code> loops and presented in the UI. e.g. make a call to REST API of Books, then make a call to REST API of Authors who have written those books. Run a <code>for</code> nested for-loop(n^2 complexity) to combine the result and show information of both books and authors in one single summary view.  </p>
  
  <p>Is this an acceptable practice or is it breaking some core concepts of what GraphQL is not supposed to do?  </p>