Delete Item With References

[mashaalmemon]

I've looked at the documentation and looked on the internet for similar questions/examples but I may have missed them. Apologies if the answer to this is trival.

I have a basic toy example I'm using to wrap my brain around MobX-State-Tree concepts.

import { computed, observable } from 'mobx';
import { observer } from 'mobx-react';

import { types, getRoot, destroy } from 'mobx-state-tree';


/**
 * User responsible for tasks
 */
const User = types.model({
  name: types.string,
  id: types.identifier(types.number),

})

/**
 * Todo that must be done
 */
const Todo = types.model({
  text: types.string,
  id: types.identifier(types.number),
  // define user responsible as a reference, with late resolution so as to avoid errors
  userResponsible: types.maybe(types.reference(types.late(()=>User)))

})

const Store = types.model({
  todos: types.map(Todo),
  users: types.map(User)
}).actions((self) => {
  return {
    addTodo (todo: typeof Todo.Type) {
      if (todo.userResponsible) {
        let root = getRoot(self);
        root.addUser(todo.userResponsible);
        // @ts-ignore
        todo.userResponsible = todo.userResponsible.id.toString();
      }
      // using maps, and overwriting ids
      self.todos.put(todo);
    },
    removeTodo(todo: typeof Todo.Type) {
      // using maps and deleting based on id
      self.todos.delete(todo.id.toString());
    },
    addUser(user: typeof User.Type) {
      self.users.put(user);
    },
    removeUser(user: typeof User.Type) {
      // using maps and deleting based on id
      self.users.delete(user.id.toString());
      // can also do:
      // destroy(user);
    }
  }
});

If I have added a todo that has a reference to users, but then I execute removeUser I get an error:

Failed to resolve reference of type late(() => User): '2' (in: /todos/1/userResponsible)

Is there a way to delete an object being referred to (in my case User) and having the item referring to it (in my case Todo) have its references set to 'null' perhaps? Or some prescribed way to delete items like this?

[elektronik2k5]

You can use a types.safeReference to have MST do the bookkeeping for you.

[mashaalmemon]

Thanks for the quick feedback @elektronik2k5 . The tutorials I was following were just using references, and so I totally missed that!