Why does find_child not work during _ready, but looping over child nodes finds the child?

Question

I have been trying to split a game object in half, starting with splitting the collision shape in half. I create two new clones of the split object, then give them a property to be assigned to the collision polygon. In the editor, the setup looks like this:

The health_xxx are sprites to be changed based on how damaged it is. In code, I do this:

      // two paths created from the original shape
      std::array<PackedVector2Array*, 2> paths {&path1, &path2};
      
      for (const auto* path : paths)
      {
        ShootableObject* myCopy = (ShootableObject*)duplicate(DUPLICATE_SIGNALS & DUPLICATE_SCRIPTS);
        // this is the path to be assigned when the object is ready
        myCopy->collisionOverride = *path;
        get_parent()->add_child(myCopy);
      }

In _ready, I tried to do find_child and Object::cast_to, but that doesn't work. The following code works and demonstrates my problem:

  if (collisionOverride.size() > 0)
  {
    CollisionPolygon2D* collision = Object::cast_to<CollisionPolygon2D>(find_child("collision"));
    if (collision)
    {
      // never happens
      collision->set_polygon(collisionOverride);
    }
    else
    {
      UtilityFunctions::print("Cannot override collision, node not found! Trying alternative method");
      for (int i = 0; i < get_child_count(); ++i)
      {
        Node* child = get_child(i);
        if (child->get_name() != StringName("collision"))
        {
          continue;
        }
        if (collision = Object::cast_to<CollisionPolygon2D>(child))
        {
          // this works
          collision->set_polygon(collisionOverride);
          UtilityFunctions::print("Success.");
          break;
        }
      }
    }
  }

The output I get:

Cannot override collision, node not found! Trying alternative method
Success.

I just don't understand why do I have to reimplement find_child in this case. Even stranger is the fact that for nodes that exist from the start, this is not a problem.

I am using Godot 4.2.

Answer 1

find_child docs say:

Node find_child ( String pattern, bool recursive=true, bool owned=true ) const

...

If owned is true, this method only finds nodes who have an assigned owner. This is especially important for scenes instantiated through a script, because those scenes don't have an owner.

Creating clones sounds like spawning the nodes via script, so they don't have owners.

In your hierarchy, you don't need recursive either. When you don't need recursive, it's good to disable it because find_child searches depth first.

So as Mangata said, use find_child("collision", false, false).