title: GraphQL gem with Rails, can't seem to find correct type definition?
body: <p>I've defined a UserType as such:</p>
  
  <pre><code>class Types::UserType &lt; GraphQL::Schema::Object
    field :id, ID, null: false
    field :username, String, null: false
    field :full_name, String, null: true
  end
  </code></pre>
  
  <p>Each of these fields exists on the Rails model, and pre 1.8 upgrade of the GraphQL Gem, I was able to use full_name in queries just fine. </p>
  
  <p>When I run the query:</p>
  
  <pre><code>query {
    users {
      username
      id
      full_name
    }
  }
  </code></pre>
  
  <p>I get: <code>"message": "Field 'full_name' doesn't exist on type 'User'",</code></p>
  
  <p>If I remove <code>full_name</code>, I get the data I expect. In what way am I approaching this incorrectly? For reference, my <code>QueryType</code> is defined as:</p>
  
  <pre><code>class Types::QueryType &lt; GraphQL::Schema::Object
    # Add root-level fields here.
    # They will be entry points for queries on your schema.
    field :users, [UserType, null: true], null: false do
      argument :id, Integer, required: false
    end
  
    def users(**args)
      args[:id]
      if args[:id]
        User.where(id: args[:id])
      else
        User.all
      end
    end
  end
  </code></pre>