DELETE removes more entries than it should

[on3iro]

maybe related to: #578 #545 #13 #721

Hey, I have the following database model:

{
  "boards": [
    {
      "id": "BOARD1",
      "project": "My Project"
    }
  ],
  "lists": [
    {
      "id": "LIST0",
      "boardId": "BOARD1",
      "title": "To Do",
      "position": 0
    },
    {
      "id": "LIST1",
      "boardId": "BOARD1",
      "title": "Doing",
      "position": 1
    },
    {
      "id": "LIST2",
      "boardId": "BOARD1",
      "title": "Review",
      "position": 2
    },
    {
      "id": "LIST3",
      "boardId": "BOARD1",
      "title": "Closed",
      "position": 3
    }
  ],
  "tasks": [
    {
      "id": "TASK0",
      "previousTaskId": "null",
      "nextTaskId": "TASK1",
      "title": "Do something!",
      "estimate": 30,
      "spent": 10,
      "dueDate": "17.11.2017",
      "listId": "LIST0",
      "boardId": "BOARD1",
      "description": "This is a very intersting task and I will probably do it",
      "userId": "",
      "client": "",
      "status": "done",
      "division": "development"
    },
    {
      "id": "TASK1",
      "previousTaskId": "TASK0",
      "nextTaskId": "null",
      "title": "Create a task board",
      "dueDate": "17.11.2017",
      "userId": "USER2",
      "listId": "LIST0",
      "boardId": "BOARD1",
      "description": "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et",
      "readOnly": true,
      "status": "blocked",
      "division": "design"
    },
    {
      "id": "TASK2",
      "previousTaskId": "null",
      "nextTaskId": "null",
      "title": "Do the dishes!",
      "estimate": 50,
      "spent": 45,
      "dueDate": "17.11.2017",
      "userId": "USER0",
      "listId": "LIST1",
      "boardId": "BOARD1",
      "description": "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et",
      "client": "",
      "division": "design"
    },
    {
      "id": "TASK3",
      "previousTaskId": "null",
      "nextTaskId": "TASK4",
      "title": "Have fun",
      "estimate": 40,
      "spent": 28,
      "dueDate": "17.11.2017",
      "userId": "",
      "listId": "LIST2",
      "boardId": "BOARD1",
      "description": "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et"
    },
    {
      "id": "TASK4",
      "previousTaskId": "TASK3",
      "nextTaskId": "TASK5",
      "title": "Yawn three times",
      "estimate": 40,
      "spent": 5,
      "dueDate": "17.11.2017",
      "userId": "USER1",
      "listId": "LIST2",
      "boardId": "BOARD1",
      "status": "blocked",
      "division": "development"
    },
    {
      "id": "TASK5",
      "previousTaskId": "TASK4",
      "nextTaskId": "TASK6",
      "title": "Boing",
      "estimate": 35,
      "dueDate": "17.11.2017",
      "userId": "USER1",
      "listId": "LIST2",
      "boardId": "BOARD1",
      "client": ""
    },
    {
      "id": "TASK6",
      "previousTaskId": "TASK5",
      "nextTaskId": "null",
      "title": "Ding",
      "estimate": 80,
      "dueDate": "17.11.2017",
      "userId": "USER1",
      "listId": "LIST2",
      "boardId": "BOARD1",
      "status": "done"
    }
  ],
  "users": [
    {
      "id": "USER0",
      "name": "",
      "avatarUrl": "img/male3-256.png"
    },
    {
      "id": "USER1",
      "name": "",
      "avatarUrl": ""
    },
    {
      "id": "USER2",
      "name": "",
      "avatarUrl": "img/photo.jpg"
    }
  ],
  "logging": []
}

If I try to DELETE lets say TASK4 however, instead of just deleting the specified task,
also a few other tasks get (randomly?) deleted:

{
    ...,
"tasks": [
    {
      "id": "TASK1",
      "previousTaskId": "TASK0",
      "nextTaskId": "null",
      "title": "Create a task board",
      "dueDate": "17.11.2017",
      "userId": "USER2",
      "listId": "LIST0",
      "boardId": "BOARD1",
      "description": "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et",
      "readOnly": true,
      "status": "blocked",
      "division": "design"
    },
    {
      "id": "TASK2",
      "previousTaskId": "null",
      "nextTaskId": "null",
      "title": "Do the dishes!",
      "estimate": 50,
      "spent": 45,
      "dueDate": "17.11.2017",
      "userId": "USER0",
      "listId": "LIST1",
      "boardId": "BOARD1",
      "description": "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et",
      "client": "BNW",
      "division": "design"
    },
    {
      "id": "TASK5",
      "previousTaskId": "TASK4",
      "nextTaskId": "TASK6",
      "title": "Boing",
      "estimate": 35,
      "dueDate": "17.11.2017",
      "userId": "USER1",
      "listId": "LIST2",
      "boardId": "BOARD1",
      "client": "ILB"
    },
    {
      "id": "TASK6",
      "previousTaskId": "TASK5",
      "nextTaskId": "null",
      "title": "Ding",
      "estimate": 80,
      "dueDate": "17.11.2017",
      "userId": "USER1",
      "listId": "LIST2",
      "boardId": "BOARD1",
      "status": "done"
    }
}

Any idea what could be the problem here? I have been stuck at this for hours and can't seem to wrap my head around this issue. There seems to be no relationship between the deleted tasks, so I have no clue at all, why json-server is doing this.

[liorcode]

DELETE has a somewhat strange behavior. It has an undocumented behavior of deleting ALL the entities that reference to entities that don't exist (as @typicode wrote in #13).

The thing is, it doesn't only remove entities that reference to the one you just deleted: it goes through the entire database and removes ANY entities which point to non existing entities - even in an entirely different table.

In your case for example, task0 and task3 got deleted because they point to a user entity which doesn't exist - "userId": ""

I believe this action is very confusing, and undocumented; I'll try and find type to submit a PR to address that.