Godot Editor Bug: Empty Node References In Nested Arrays

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Godot Editor Bug: Empty Node References in Nested Arrays

Hey Godot community! Have you ever run into a frustrating issue where your node references are mysteriously disappearing when you try to store them in nested arrays within the Godot editor? I've got some bad news: you're not alone! It seems like there's a bug causing node references to become <empty> when they're stored in nested arrays, even though they work fine during runtime. Let's dive into this annoying problem and what you can do about it.

The Problem: Empty Node References

So, what exactly is happening? The issue revolves around storing references to nodes (like Node2D, Button, or any custom node you create) inside an array of arrays within the Godot editor. You might be using a tool script to gather these references using methods like exported fields or get_nodes_in_group(). The script assembles this nested array structure, expecting to store those crucial node references. The structure appears correct in the editor's inspector panel, but all the node references are just blank. When you save and reload the scene, restart the editor, or do anything else that triggers a re-evaluation of the scene data, those references stay empty. This is super frustrating because it breaks your intended workflow, especially if you rely on this nested structure for organizing and accessing your nodes.

Here’s a breakdown of what doesn't work, based on the original report:

  • You have a tool script with an exported array of arrays (the type hints are optional).
  • Within the script, you get references to some nodes (via an exported field, get_nodes_in_group, etc.).
  • You add an array of these node references to the first array.
  • You inspect the exported array in the editor. The array structure exists, but all the references are <empty>.
  • Saving and reloading the scene, restarting the editor, etc., doesn't fix the issue.

This behavior is particularly perplexing because node references can be stored in nested structures without any problems during runtime. It's only in the editor that this bug rears its ugly head. This discrepancy can lead to unexpected behavior and a lot of debugging headaches. The user reported that they expect the editor to behave the same way as runtime, where nested references do work. The bug prevents proper scene setup and can force developers to find alternative, more cumbersome ways to manage their node references, thus impacting the efficiency of the workflow.

Affected Godot Versions and System Information

The bug has been identified in Godot versions 4.5.1.stable.official and 4.4.1.stable.official. The issue description also includes detailed system information, like the operating system (Ubuntu 25.04), the display driver (X11), the graphics card (NVIDIA GeForce RTX 4070), and the processor (AMD Ryzen 7 5700X3D). However, these details, while informative, aren't directly related to the bug itself. It's likely a more general issue affecting how the Godot editor serializes and deserializes node references within nested array structures, and this particular bug could affect users on different hardware and software configurations.

Steps to Reproduce the Bug

To make it super clear, here are the exact steps to reproduce the issue, as described in the original bug report:

  1. Open the test scene: Start by opening a test scene that demonstrates this problem.
  2. Select the tester node: Choose the specific node that contains the script causing the issue.
  3. Click the "Fill Arrays" button: This action triggers the script to populate the nested array with node references.
  4. Unfold the Nested Nodes array: In the editor's inspector, expand the array to reveal its contents.
  5. Observe the empty references: You'll see that, despite the array structure existing, all the node references are displayed as <empty>.

This methodical approach helps to isolate and understand the problem. The user also included a Minimal Reproduction Project (MRP), which is immensely helpful, because it allows anyone to easily replicate the issue and see it firsthand. The inclusion of an MRP is standard practice when reporting bugs in software, because it allows developers to quickly diagnose the problem.

What to Do? Workarounds and Potential Solutions

So, what can you do if you're stuck with this bug? Here are a few workarounds and potential solutions:

  • Avoid Nested Arrays (Temporary Solution): The simplest workaround is to avoid using nested arrays altogether for storing node references in the editor. Consider using a flat array, a dictionary, or another data structure that doesn't involve nested arrays.
  • Use a Different Approach: Instead of directly storing node references, you might be able to store the node's name or path and then look up the node at runtime using get_node() method. This will give you the node you want. This approach, while more indirect, may work until the issue is fixed.
  • Report the Bug (If You Haven't Already): If you haven't already, please report the bug on the Godot issue tracker (if it hasn't been reported already). Include detailed steps to reproduce the issue, the Godot version you're using, and, of course, a minimal reproduction project. More reports will increase the likelihood of the bug getting fixed promptly!
  • Contribute to Godot: If you are a C++ programmer, you could contribute to the Godot project by helping find the cause of the bug and creating a fix. This would be a welcome effort and it would help you understand the engine much better.
  • Stay Updated: Keep an eye on Godot's release notes and the issue tracker for updates on this problem. The developers will likely address this issue in a future release.

Conclusion

This is a frustrating bug, but hopefully, knowing about it helps you manage your projects effectively. Remember, it's essential to report the problem and, if you have the technical skills, help find a fix. Keep an eye on Godot's updates, and hopefully, this will be resolved soon. Good luck, and happy Godot-ing!

I hope this explanation of the bug and potential solutions is useful to you all! If you have any other questions or different solutions, please comment below. Happy coding!