Loopback-next: TodoList tutorial - GET ​/todos​/{id}​/todo-list gives unexpected response

[emonddr]

TodoList tutorial - GET ​/todos​/{id}​/todo-list gives unexpected response
for a todo item that is not part of a todo list.

Current Behavior

In the Todo tutorial, a few todo items are already inside db.json.

[
  {
    "id": 1,
    "title": "Take over the galaxy",
    "desc": "MWAHAHAHAHAHAHAHAHAHAHAHAHAMWAHAHAHAHAHAHAHAHAHAHAHAHA"
  },
  {
    "id": 2,
    "title": "destroy alderaan",
    "desc": "Make sure there are no survivors left!"
  },
  {
    "id": 3,
    "title": "play space invaders",
    "desc": "Become the very best!"
  },
  {
    "id": 4,
    "title": "crush rebel scum",
    "desc": "Every.Last.One."
  },
]

They are not associated with any list.
No problem.

I reach the end of the TodoList tutorial
I create a TodoList #1
I add two new todo items to it.
No problem.

[
  {
    "id": 1,
    "title": "Take over the galaxy",
    "desc": "MWAHAHAHAHAHAHAHAHAHAHAHAHAMWAHAHAHAHAHAHAHAHAHAHAHAHA"
  },
  {
    "id": 2,
    "title": "destroy alderaan",
    "desc": "Make sure there are no survivors left!"
  },
  {
    "id": 3,
    "title": "play space invaders",
    "desc": "Become the very best!"
  },
  {
    "id": 4,
    "title": "crush rebel scum",
    "desc": "Every.Last.One."
  },
  {
    "id": 5,
    "title": "carrots",
    "desc": "White Carrots for soup",
    "isComplete": false,
    "todoListId": 1
  },
  {
    "id": 6,
    "title": "bananas",
    "desc": "Yellow bananas for banana bread",
    "isComplete": false,
    "todoListId": 1
  },
]

When I use
GET /todos​/{todo id}/todo-list for the two new todo items (id=5 or 6) above, I get the
proper response of

{
  "id": 1,
  "title": "grocery",
  "color": "green"
}

No problem.

But when I use
GET /todos​/{todo id}/todo-list for the any item items (id=1 through 4) above (not associated with a list), I get the unexpected response of:

{
  "id": 1,
  "title": "grocery",
  "color": "green"
}

todo with id=1 is not part of todoList id=1.

Expected Behavior

Expected a response of [ ].

Link to reproduction sandbox

Related Issues

_See Reporting Issues for more tips on writing good issues_

Acceptance Criteria

• [ ] Find the underlying resolver's problem which returns orphan related item.
• [ ] Fix the bug ^.

[dhmlau]

@emonddr, I've followed the todo list tutorial and reproduced the problem.

For the Additional Information:

1. There is a TodoListImageController in finished tutorial that is not part of the tutorial instructions

I think we didn't cover that hasOne relation in the tutorial. I was hoping to add that into the tutorial once we have the cli support: https://github.com/strongloop/loopback-next/issues/2980.

1. The Todo and TodoList models don't seem to have navigational properties. See TodoListRelations as an example ( the completed tutorial has properties: todos? and image? )

To clarify your point, I think the generated code shows:

export interface TodoListRelations {
  // describe navigational properties here
}

but in the example code, it has:

export interface TodoListRelations {
  todos?: TodoWithRelations[];
  image?: TodoListImageWithRelations;
}

The generated code seems to work fine, but it would be good if we have both places consistent. Perhaps @nabdelgadir or @agnes512 can comment on that?

1. there is a difference in whether the id field is required and generated in the Todo and TodoList models.

Does it make sense to make the id field auto-generated for both cases?

? Enter the property name: id
? Property type: number
? Is id the ID property? Yes
? Is id generated automatically? Yes

[agnes512]

Hmm. I thought 2 was solved in https://github.com/strongloop/loopback-next/issues/3742 (add explanations for interfaces such as TodoListRelations..)

And the main problem in 3 is id should be required but in the tutorial is false.

[dhmlau]

For 2, I think the issue here is the generated code is different from the code in the examples/todo-list package.

[emonddr]

Even specifying
id is ID field
id is autogenerated
for both Todo and TodoList models, and following all the instructions in the Todo Tutorial and TodoList tutorial, there is still a bug with:

GET /todos​/{todo id}/todo-list ; where todo id =1 (not part of a todo list)

[emonddr]

@bajtos , are the navigational properties for TodoListRelations supposed to be filled in by lb4 relation command, or by hand? Please advise. thanks. (see comment and Diana's comments above regarding TodoListRelations)

[bajtos]

are the navigational properties for TodoListRelations supposed to be filled in by lb4 relation command, or by hand?

The navigational properties will be filled by lb4 relation once we implement #2988, that's a known feature that we are missing.

For now, users have to fill the interface entries manually.

[bajtos]

Does it make sense to make the id field auto-generated for both cases?

Personally, I'd prefer to make the ID always generated by the database (property defined with generated: true and model defined with setting forceId: true unless forceId is applied automatically for auto-generated PKs, which probably is).

[emonddr]

Adding the navigational properties by hand to to the Todo and TodoList models doesn't fix the bug I am seeing.

[dhmlau]

There seems to be more than one issue captured in this ticket. I'd like to propose:

1. Keep this issue as the bug reported in the original description
2. Open another issue to make sure the tutorials is up-to-date, e.g.
   
   
   
   • we need to add the navigational properties by hand.
   
   
   • make the 2 models' id to be autogen.
   
   

@emonddr , could you please create a new ticket for #2? Thanks.

[dhmlau]

This is a stretch goal for Q4. Could you please:

• add acceptance criteria to this issue
• open a new issue based on the above comment?
  Thanks!

[emonddr]

I have moved the conversation of the differences between the TodoList Tutorial instructions and completed tutorial contents in lb4 example todo-list to the issue: https://github.com/strongloop/loopback-next/issues/4161

This issue is now only about the problem described in the Description.