title: Return any data from a query using GraphQL, Graphene and Python
body: <p>I am receiving the following error:</p>
  
  <pre><code>{
    "errors": [
      {
        "message": "Unknown argument \"project_id\" on field" +
                   \"get_project_detail_summary\" of type \"Query\".",
        "locations": [
          {
            "line": 2,
            "column": 30
          }
        ]
      }
    ]
  }
  </code></pre>
  
  <p>With the following query:</p>
  
  <pre><code>query GetProjectDetailSummary($project_id: Int) {
    get_project_detail_summary(project_id: $project_id) {
      comments {
        ... on ManagerCommentNode {
          id
          text
          created
        }
        ... on VendorCommentNode {
          id
          text
          created
        }
        ... on TenantCommentNode {
          id
          text
          created
        }
      }
    }
  }
  </code></pre>
  
  <p>With the following backend code, How can I get to the breakpoint?, or how do I send back custom data given a number?:</p>
  
  <pre class="lang-py prettyprint-override"><code>class CommentsUnion(graphene.types.union.Union):
      class Meta:
          name = 'CommentsUnion'
          types = (ManagerCommentNode, VendorCommentNode, TenantCommentNode, )
  
  
  class ProjectSummaryInput(graphene.InputObjectType):
      project_id = graphene.Int()
  
  
  class ProjectSummaryNode(graphene.ObjectType):
      Input = ProjectSummaryInput
  
      project_id = graphene.Int()
      comments = graphene.List(CommentsUnion)
  
      @classmethod
      def resolve_comments(self, *args, **kwargs):
          import pdb;pdb.set_trace()
          return ProjectSummary.select_related('comments').objects.filter(comments__created__lt=dt)
  
  class Query(graphene.ObjectType):
      get_project_detail_summary = Field(ProjectSummaryNode)
  
  </code></pre>