title: GraphQL List or single object
body: <p>I got the following "problem". I am used to having an API like that. </p>
  
  <pre><code>/users
  /users/{id}
  </code></pre>
  
  <p>The first one returns a list of users. The second just a single object. I would like the same with GraphQL but seem to fail. I got the following Schema</p>
  
  <pre><code>var schema = new GraphQLSchema({
    query: new GraphQLObjectType({
      name: 'Query',
      fields: {
        users: {
          type: new GraphQLList(userType),
          args: {
            id: {type: GraphQLString}
          },
          resolve: function (_, args) {
            if (args.id) {
              return UserService.findOne(args.id).then(user =&gt; [user]);
            } else {
              return UserService.find()
            }
          }
        }
      }
    })
  });
  </code></pre>
  
  <p>How can I modify the type of users to either return a List OR a single object? </p>