Godot: Is there any way I can invoke a method in my Script from the editor? (for testing purposes)

Question

I come from Unity, and there you can use ContextMenu method attribute. It will add a button in the editor you can click and the method in your script will be invoked.

This is very helpful for testing/debugging purposes. When you are testing a functionality and you want an easy way to trigger it.

Is there something similar in Godot, or any workaround I can use?

(Godot 3.5 here)

Answer 1

There are multiple ways to run code in the editor.

In fact, Godot games and the Godot editor are built on the same core. One way to say is that Godot is build on Godot… But a more accurate way to say it is that your games are Godot without the editor, plus whatever you built on top.

As a consequence, you have a lot of freedom when extending the Godot editor.

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For starters you will be making a tool script. To do that you the tool keyword on the top of the script file. This allows the script to run in the editor.

Warning: Remember that in Godot the Game is not running inside the Editor. Anything that your script moves while running in the Editor would be a modification to the project, for good or ill. And it does not come with build-in undo functionality. It is possible to add undo functionality (with the UndoRedo class), but that is also something you would have to program.

By the way, you might want to know if your code is running on the editor or not. For that, you can check Engine.editor_hint which will be true in the editor.

Read more on the article Running code in the editor.

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Since the tool script modify the project. What I present below is more often used to setup parts of the scene or to automate parts of the development workflow. Not for testing features. However since the linked documentation about ContextMenu mentions that it is useful for…

automatically setting up Scene data from the script

I believe what present below is not out of place.

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With that said, some modifications of the editor are harder than others. I believe you don't really want to go into the trouble of adding a button to the editor (which is perfectly possible) or an option to the menus (which is also possible, but not everywhere, at least not easily). Instead, I'll stay with the easy options for this answer:

• You can make an EditorScript. That is a script that extends the EditorScript class and overrides the _run method. For example:

  tool
  extends EditorScript
  
  func _run():
      print("Hello from the Godot Editor!")
  

  To execute it, have it open in the Script Editor, and to the File menu, and select Run. You can also use secondary click on the script on the "Scripts Panel (on the left of the Script Editor) and select Run in the contextual menu.

  The drawback is that is script does not work in the game. It is only for the editor.

• Although Godot 3.x does not have official (there is a plugin) support for inspector actions (it might land in Godot 4), we can workaround that. What we will do is export a bool property, and handle (with a setter, which we specify with setget) what happens when you set it. Like this:

  tool
  extends Node # or whatever
  
  export var do_something:bool setget on_do_something
  
  func on_do_something(_mod_value:bool) -> void:
      # do whatever you want
      pass
  

  The property should show up as a checkbox in the Inspector panel when the node is selected. And clicking the checkbox will trigger the setter method on_do_something… Which will do whatever you want it to do. Notice also that I'm discarding the value that Godot is trying to set to the property (_mod_value) so it will remain false.

  This pattern has got popularity among Godot developers.

If you want to add elements to the Godot UI you would have to make an EditorPlugin (see the Editor Plugins section in the documentation).

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Alright but, since the tool script could cause modifications to the project, which might be a problem for testing… What do we do for testing?

Well, I will remind you that you can tell Godot to execute specific scenes (it does not have to run the main scene), and that can another way to test your code.

Furthermore, when your game is running you can go to the Scene panel and select the Remote tab to see the Nodes that exist in the game. Which will allow you to select them, which shows their properties in the Inspector, which would be able to modify (having an effect in real time on the executing game).

… And thus something similar to what I described above about using a setter would work. Except it does not need the tool keyword since it won't be running in the editor:

# No tool
extends Node # or whatever

export var do_something:bool setget on_do_something

func on_do_something(_mod_value:bool) -> void:
    # do whatever you want
    pass

By the way, in the inspector, when the game is executing and you have the relevant Node selected, you will see your property twice. The first one will trigger the setter, while the second one bypasses it. So pay attention which one you are using.

You might also be interested in the "Project Camera Override" feature, which allows you to freely move the game camera from the editor. You access the feature via the top bar in the editor.

You will also find that it is possible to modify Resources in the editor and see the effect in real time while the game is running. And a Script is a Resource… However pause the game from the Debugger panel (or use a breakpoint) and make sure the script you want to modify is not being executed before you modify it.