How to force binding re-evaluate or re-rendering in Aurelia

Question

I am starting with a simple TODO app with Aurelia, RethinkDB & Socket.IO. I seem to have problem with re-rendering or re-evaluating an object that is changed through Socket.

Answer 1

Aurelia observes changes to the contents of an array by overriding the array's mutator methods (push, pop, splice, shift, etc). This works well for most use-cases and performs really well (no dirty-checking, extremely lightweight in terms of memory and cpu). Unfortunately this leaves one way of mutating an array that aurelia can't "see": indexed assignment... eg myArray[6] = 'foo'. Since no array methods were called, the binding system doesn't know the array changed.

In your case, try changing this:

// update item
socket.on("todo_update", data => {
  let pos = arrayFindObjectIndex(this.items, 'id', data.id);
  if(pos >= 0) {
    console.log('before update');
    console.log(this.items[pos]);

    this.items[pos] = data; // <-- change this to: this.items.splice(pos, 1, data);

    this.items[pos].title = this.items[pos].title + ' [updated]';
    console.log('after update');
    console.log(this.items[pos]);
  }
});