editor-scripting-and-python

name	editor-scripting-and-python
description	Automate and extend the Unreal Editor using Python (the `unreal` module, startup scripts, commandlets), Editor Utility Widgets/Blueprints (Blutility — UEditorUtilityWidget, UEditorUtilityObject, UEditorUtilityWidgetBlueprint, UAssetActionUtility), the editor scripting subsystems (UEditorActorSubsystem, UEditorAssetSubsystem, ULevelEditorSubsystem, UAssetEditorSubsystem, UEditorUtilitySubsystem), and how C++ UFUNCTION specifiers (BlueprintCallable, CallInEditor, ScriptMethod, ScriptName) control which APIs surface in Python and Blueprints. Use when batch-processing assets, building in-editor tools or dockable UMG panels, running headless Python commandlets in CI, scripting repetitive editor tasks, or exposing custom C++ editor APIs to Python/Blueprints. Editor-only — never used in packaged games.
metadata	{"engine-version":"5.8","category":"tooling"}

Editor scripting & Python

Everything in this skill is editor-only: it lives in editor modules or behind WITH_EDITOR and is stripped from packaged games. The two main paths are: the Python Script Plugin (unreal module) for quick automation and pipeline scripts, and Blutility (Editor Utility Widgets/Blueprints) for in-editor UI tools callable by artists and designers.

When to use this skill

• Batch operations on assets — rename, set properties, reimport, generate LODs.
• Custom in-editor UMG panels (Editor Utility Widgets) for artists.
• Context-menu scripted actions triggered from the Content Browser or Level.
• Headless commandlet runs in CI without the full editor UI.
• Exposing a C++ function so it appears in Python/Blueprints with the correct name.
• Obtaining a reference to an editor subsystem from C++ or Python.

Approach comparison

Approach	When to choose
Python (PythonScriptPlugin)	Pipeline automation, batch asset ops, CI jobs, quick scripts
Editor Utility Widget (Blutility)	Artist-facing tool panels with UMG UI in the editor
Editor Utility Blueprint	No-UI scripted actions on assets or actors
C++ editor module + UEditorSubsystem	Robust reusable tools, Slate/menu extensions
Commandlet	Headless batch processing, -run=pythonscript in CI

---

Python (unreal module)

Enable the Python Editor Script Plugin (Plugins > Scripting). The plugin bundles Python 3.11.8; no separate install is needed. The unreal module is generated at startup from whatever is reflected to Blueprints — any BlueprintCallable function or class exposed by any enabled plugin is automatically available.

Naming convention: C++ class UEditorAssetSubsystem → Python class unreal.EditorAssetSubsystem. Function GetAllLevelActors() → get_all_level_actors(). Enum values become UPPER_SNAKE_CASE. The U/A/F/T prefix is dropped.

Reading/setting properties:

import unreal

actor = unreal.EditorActorSubsystem().get_actor_reference("PersistentLevel.MyActor")
# BlueprintReadWrite → direct attribute access
val = actor.some_property
# EditAnywhere → use get/set_editor_property for pre/post-edit notifications
actor.set_editor_property("hidden_in_game", True)

Transactions (undo/redo support):

with unreal.ScopedEditorTransaction("Batch rename"):
    for asset in assets:
        subsystem.rename_asset(asset.get_path_name(), new_path)

Progress feedback for long jobs:

with unreal.ScopedSlowTask(len(assets), "Processing...") as task:
    task.make_dialog(True)
    for asset in assets:
        if task.should_cancel():
            break
        task.enter_progress_frame(1, f"Processing {asset.get_name()}")
        # ... do work

Startup scripts — add paths under Project Settings → Plugins → Python → Startup Scripts (stored in UPythonScriptPluginSettings::StartupScripts, Plugins/Experimental/PythonScriptPlugin/Source/PythonScriptPlugin/Private/PythonScriptPluginSettings.h:67). Auto-detected init_unreal.py in any Content/Python folder also runs on startup.

Commandlet (headless): UPythonScriptCommandlet runs a script without the full UI:

UnrealEditor-Cmd.exe MyProject.uproject -run=pythonscript -script="my_script.py"

Source: Plugins/Experimental/PythonScriptPlugin/Source/PythonScriptPlugin/Private/PythonScriptCommandlet.h:10.

See references/python-api.md for the C++↔Python mapping, get_editor_subsystem, type coercion, logging, and subsystem access patterns.

---

Editor Utility Widgets & Blueprints (Blutility)

Blutility classes live in Editor/Blutility/. The module is Blutility; add it to your editor module's PrivateDependencyModuleNames.

Key classes

Class	Base	Purpose
UEditorUtilityWidget	UUserWidget	Dockable UMG panel running in the editor
UEditorUtilityWidgetBlueprint	UWidgetBlueprint	Asset that generates UEditorUtilityWidget
UEditorUtilityObject	UObject	Editor-only utility with no UI; runs on demand
UAssetActionUtility	UEditorUtilityObject	Right-click scripted actions in the Content Browser
UEditorUtilityTask	UObject	Background task managed by UEditorUtilitySubsystem

UEditorUtilityWidget (Editor/Blutility/Classes/EditorUtilityWidget.h:27): inherits UUserWidget; runs entirely in editor. Run() is a BlueprintImplementableEvent called when the widget is auto-run. Use TabDisplayName to set the panel name.

UEditorUtilityObject (Editor/Blutility/Classes/EditorUtilityObject.h:20): pure-logic utility, no UI. Set bRunEditorUtilityOnStartup = true to auto-run after asset discovery.

UAssetActionUtility (Editor/Blutility/Classes/AssetActionUtility.h:60): any UFUNCTION(BlueprintCallable) on a subclass appears as a right-click option in the Content Browser. Populate SupportedClasses (class defaults) to filter which asset types show the action. GetSupportedClass() is deprecated since UE 5.2.

UEditorUtilitySubsystem manages widget tabs and utility tasks (Editor/Blutility/Public/EditorUtilitySubsystem.h:47):

// Open an Editor Utility Widget tab from C++:
UEditorUtilitySubsystem* EUS = GEditor->GetEditorSubsystem<UEditorUtilitySubsystem>();
EUS->SpawnAndRegisterTab(MyWidgetBlueprint);  // line 88
// From Python:
// eus = unreal.get_editor_subsystem(unreal.EditorUtilitySubsystem)
// eus.spawn_and_register_tab(widget_bp)

See references/editor-utility-widgets.md for Widget setup, tab lifecycle, UEditorUtilityTask, and scripted-actions detail.

---

Editor scripting subsystems

All subsystems inherit UEditorSubsystem. Access them via GEditor->GetEditorSubsystem<T>() in C++ or unreal.get_editor_subsystem(T) in Python.

UEditorActorSubsystem (Editor/UnrealEd/Public/Subsystems/EditorActorSubsystem.h:49)

Actor-level operations in the current level editor world:

UEditorActorSubsystem* AS = GEditor->GetEditorSubsystem<UEditorActorSubsystem>();
TArray<AActor*> All   = AS->GetAllLevelActors();       // :166
TArray<AActor*> Sel   = AS->GetSelectedLevelActors();  // :181
AActor* Placed = AS->SpawnActorFromClass(MyClass, Location); // :228
AS->DestroyActor(ActorToRemove);                       // :236

Python: unreal.get_editor_subsystem(unreal.EditorActorSubsystem).get_all_level_actors()

UEditorAssetSubsystem (Editor/UnrealEd/Public/Subsystems/EditorAssetSubsystem.h:38)

Content-browser asset operations (the preferred replacement for UEditorAssetLibrary):

UEditorAssetSubsystem* EAS = GEditor->GetEditorSubsystem<UEditorAssetSubsystem>();
UObject* Loaded = EAS->LoadAsset("/Game/MyFolder/MyAsset"); // :54
EAS->SaveAsset("/Game/MyFolder/MyAsset");                   // :296
EAS->DuplicateAsset("/Game/Src", "/Game/Dst");              // :185
EAS->RenameAsset("/Game/Src", "/Game/Dst");                 // :215
EAS->DeleteAsset("/Game/MyFolder/MyAsset");                 // :155

ULevelEditorSubsystem (Editor/LevelEditor/Public/LevelEditorSubsystem.h:38)

Level-file and viewport operations:

ULevelEditorSubsystem* LS = GEditor->GetEditorSubsystem<ULevelEditorSubsystem>();
LS->NewLevel("/Game/Maps/MyLevel");        // :147
LS->LoadLevel("/Game/Maps/Existing");      // :167
LS->SaveCurrentLevel();                    // :174
LS->EditorRequestBeginPlay();              // :78

UAssetEditorSubsystem (Editor/UnrealEd/Public/Subsystems/AssetEditorSubsystem.h:112)

Open assets in their specialized asset editors programmatically.

UUnrealEditorSubsystem (Editor/UnrealEd/Public/Subsystems/UnrealEditorSubsystem.h:17)

Viewport camera query/set (GetLevelViewportCameraInfo, SetLevelViewportCameraInfo) and GetEditorWorld().

See references/editor-subsystems.md for all subsystem methods and Python equivalents.

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Exposing C++ to editor scripting

UFUNCTION(BlueprintCallable) — surfaces to both Blueprints and Python

Any BlueprintCallable function on a UCLASS is reflected to Python automatically. In Python the class name loses its prefix and the function name becomes snake_case.

UFUNCTION(meta = (CallInEditor = "true")) — Details panel button

Marks a function to appear as a button in the actor Details panel when an instance is selected in the editor. Works on AActor and UActorComponent subclasses. Source: Runtime/CoreUObject/Public/UObject/ObjectMacros.h:1047.

UFUNCTION(BlueprintCallable, Category = "Validation", meta = (CallInEditor = "true"))
void ValidateSetup();

meta = (ScriptMethod) — hoist a static function as an instance method in Python

A static BlueprintFunctionLibrary function that takes a struct or object as its first parameter can be re-surfaced in Python as a method on that type:

UFUNCTION(BlueprintCallable, meta = (ScriptMethod))
static FVector ScaleVector(const FVector& V, float Factor);
// Python: v.scale_vector(2.0)  instead of  unreal.MyLib.scale_vector(v, 2.0)

Source: Runtime/CoreUObject/Public/UObject/ObjectMacros.h:1723. Related specifiers: ScriptMethodSelfReturn (:1726), ScriptMethodMutable (:1729).

meta = (ScriptName = "PythonName") — override the Python/scripting name

UFUNCTION(BlueprintCallable, meta = (ScriptName = "load_texture"))
static UTexture* LoadTexture_Internal(const FString& Path);
// Python: unreal.MyLib.load_texture(path)

Source: Runtime/CoreUObject/Public/UObject/ObjectMacros.h:1285.

---

Version notes

• UEditorAssetLibrary / UEditorLevelLibrary (EditorScriptingUtilities plugin) were deprecated in UE 5.0. UEditorLevelLibrary functions carry UE_DEPRECATED(5.0, "... Use the function in Editor Actor Utilities Subsystem"). Prefer UEditorAssetSubsystem and UEditorActorSubsystem in all new code.
• UAssetActionUtility::GetSupportedClass() deprecated UE 5.2; use the SupportedClasses array in class defaults instead.
• Python 3.11.8 is the embedded version for UE 5.8 (VFX Reference Platform CY2024). Set UE_PYTHON_DIR to embed a different CPython build (requires source rebuild).

Gotchas

• Editor-only code in a runtime module → packaging failure. Put editor code behind WITH_EDITOR or in a module with type Editor.
• Python does not ship with the game — it is a tooling/editor-only plugin.
• Direct attribute set vs set_editor_property — direct set bypasses pre/post-edit callbacks; set_editor_property triggers them (same as changing in Details panel). Use set_editor_property for EditAnywhere properties.
• Long Python jobs block the editor UI — wrap with unreal.ScopedSlowTask and yield enter_progress_frame to keep the editor responsive and allow cancellation.
• Forgetting to save — call EAS->SaveAsset() or the Python equivalent; unsaved changes to assets are lost when the editor closes.
• Hardcoding asset paths — use the Asset Registry to discover paths dynamically; see asset-management.
• SpawnActorFromClass vs SpawnActor — SpawnActorFromClass on UEditorActorSubsystem places into the editor world and notifies the editor; use it instead of UWorld::SpawnActor for editor-placed actors.

References & source material

Engine source (UE 5.8):

Blutility (Engine/Source/Editor/Blutility/):

• Classes/EditorUtilityWidget.h — UEditorUtilityWidget:27, Run():34, TabDisplayName:74
• Classes/EditorUtilityObject.h — UEditorUtilityObject:20, bRunEditorUtilityOnStartup:41
• Classes/AssetActionUtility.h — UAssetActionUtility:60, SupportedClasses, deprecated GetSupportedClass():71
• Classes/EditorUtilityTask.h — UEditorUtilityTask:32, FinishExecutingTask():56
• Public/EditorUtilitySubsystem.h — UEditorUtilitySubsystem:47, SpawnAndRegisterTab:88, RegisterAndExecuteTask:140, TryRun:76

Editor subsystems (Engine/Source/Editor/UnrealEd/Public/Subsystems/):

• EditorActorSubsystem.h — UEditorActorSubsystem:49, GetAllLevelActors:166, SpawnActorFromClass:228, DestroyActor:236
• EditorAssetSubsystem.h — UEditorAssetSubsystem:38, LoadAsset:54, SaveAsset:296, DuplicateAsset:185, RenameAsset:215, DeleteAsset:155
• AssetEditorSubsystem.h — UAssetEditorSubsystem:112
• UnrealEditorSubsystem.h — UUnrealEditorSubsystem:17, GetLevelViewportCameraInfo:32

Level editor (Engine/Source/Editor/LevelEditor/Public/):

• LevelEditorSubsystem.h — ULevelEditorSubsystem:38, NewLevel:147, LoadLevel:167, SaveCurrentLevel:174, EditorRequestBeginPlay:78

Python plugin (Engine/Plugins/Experimental/PythonScriptPlugin/):

• Source/PythonScriptPlugin/Public/IPythonScriptPlugin.h — IPythonScriptPlugin:11, ExecPythonCommand:54
• Source/PythonScriptPlugin/Private/PythonScriptCommandlet.h — UPythonScriptCommandlet:10
• Source/PythonScriptPlugin/Private/PythonScriptPluginSettings.h — StartupScripts:67, AdditionalPaths:71

Reflection/meta specifiers (Engine/Source/Runtime/CoreUObject/Public/UObject/ObjectMacros.h):

• CallInEditor:1005, ScriptName:1243, ScriptMethod:1671, ScriptMethodSelfReturn:1674, ScriptMethodMutable:1677

Deprecated (EditorScriptingUtilities plugin, prefer subsystems):

• Engine/Plugins/Editor/EditorScriptingUtilities/Source/EditorScriptingUtilities/Public/EditorAssetLibrary.h
• Engine/Plugins/Editor/EditorScriptingUtilities/Source/EditorScriptingUtilities/Public/EditorLevelLibrary.h (deprecated UE 5.0)

Official docs (UE 5.8):

• Scripting and Automating the Unreal Editor — https://dev.epicgames.com/documentation/unreal-engine/scripting-and-automating-the-unreal-editor
• Scripting the Unreal Editor Using Python — https://dev.epicgames.com/documentation/unreal-engine/scripting-the-unreal-editor-using-python
• Scripting the Unreal Editor Using Blueprints — https://dev.epicgames.com/documentation/unreal-engine/scripting-the-unreal-editor-using-blueprints
• Python API Reference — https://dev.epicgames.com/documentation/unreal-engine/PythonAPI

Deep-dive references in this skill:

• references/editor-subsystems.md — all subsystem classes, their methods, and Python equivalents.
• references/editor-utility-widgets.md — Blutility class hierarchy, tab lifecycle, UEditorUtilityTask, scripted actions.
• references/python-api.md — C++↔Python naming rules, type mapping, get_editor_subsystem, transactions, logging, commandlet invocation.

Related skills: subsystems, plugins-and-modules, asset-management.