Enum and Struct Skill

Critical Rules

Read-Only Native Types

Native C++ enums and structs are read-only. Only UserDefinedEnums and UserDefinedStructs can be modified:

import unreal

# Search for user-defined enums only (editable)
enums = unreal.EnumStructService.search_enums("Weapon", True)  # bUserDefinedOnly=True

# Check if an enum is user-defined before modifying
# (returns a single EnumInfo or None — NOT a (success, info) tuple)
info = unreal.EnumStructService.get_enum_info("EMyEnum")
if info and info.is_user_defined:          # field is is_user_defined, NOT b_is_user_defined
    unreal.EnumStructService.add_enum_value("EMyEnum", "NewValue")

🚨 Pass the EXACT asset name you want — prefixing is dumb

create_enum / create_struct only prepend E/F when the name doesn't already start with that letter; they never insert underscores or reformat. So:

• want E_TestState → pass "E_TestState" (passing "TestState" creates ETestState)
• want EWeaponType → "WeaponType" or "EWeaponType" both work

Creation fails with an empty string if the asset already exists — delete it first (delete_enum / delete_struct), there is no overwrite.

🚨 Enum values: you are always working with DISPLAY names

UserDefinedEnum entries have immutable internal names (NewEnumerator0..N). Every EnumStructService method speaks display names: the name you pass to add_enum_value becomes the display name, get_enum_values returns display names, and rename_enum_value / remove_enum_value accept display names (rename changes the display name only). For internal+display pairs use get_enum_info(...).values (each entry has name = internal, display_name, value, index).

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Workflows

Create UserDefinedEnum

import unreal

# Create a new enum — pass the exact final name (here E prefix gets prepended)
enum_path = unreal.EnumStructService.create_enum("/Game/Data/Enums", "WeaponType")
print(f"Created: {enum_path}")  # /Game/Data/Enums/EWeaponType.EWeaponType
if not enum_path:
    # creation failed — most likely the asset already exists; delete_enum first
    ...

# Add values
unreal.EnumStructService.add_enum_value(enum_path, "Sword", "Melee Sword")
unreal.EnumStructService.add_enum_value(enum_path, "Bow", "Ranged Bow")
unreal.EnumStructService.add_enum_value(enum_path, "Staff", "Magic Staff")

# Verify
values = unreal.EnumStructService.get_enum_values(enum_path)
print(f"Values: {values}")  # ['Sword', 'Bow', 'Staff']

Create UserDefinedStruct

import unreal

# Create a new struct (F prefix added automatically)
struct_path = unreal.EnumStructService.create_struct("/Game/Data/Structs", "WeaponData")
print(f"Created: {struct_path}")

# Add properties
unreal.EnumStructService.add_struct_property(struct_path, "WeaponName", "FString", "Unnamed")
unreal.EnumStructService.add_struct_property(struct_path, "Damage", "float", "10.0")
unreal.EnumStructService.add_struct_property(struct_path, "AttackSpeed", "float", "1.0")
unreal.EnumStructService.add_struct_property(struct_path, "WeaponType", "EWeaponType")  # Use our enum

# Add array property
unreal.EnumStructService.add_struct_property(struct_path, "SpecialEffects", "FName", "", "Array")

# Verify — get_struct_info returns a single StructInfo (or None), NOT a (success, info) tuple
info = unreal.EnumStructService.get_struct_info(struct_path)
if info:
    print(f"Properties: {info.property_count}")
    for prop in info.properties:
        print(f"  {prop.name}: {prop.type} (default: {prop.default_value}, guid: {prop.guid})")

Notes:

• prop.name is the authored name ("Damage") and all mutation methods (rename_struct_property, set_struct_property_default, remove_struct_property, change_struct_property_type) accept authored names. GUIDs live per property (StructPropertyInfo.guid) — StructInfo itself has no guid field.
• New structs are seeded with a placeholder bool (MemberVar_0); the first add_struct_property call removes it automatically. If you ever see a stray MemberVar_* bool in an older struct, drop it with remove_struct_property(path, "MemberVar_0").

Discover Enums and Structs

import unreal

# Search all enums containing "Weapon"
enums = unreal.EnumStructService.search_enums("Weapon")
for e in enums:
    print(f"{e.name} ({e.value_count} values) - UserDefined: {e.is_user_defined}")

# Search user-defined structs only
structs = unreal.EnumStructService.search_structs("Data", True)  # bUserDefinedOnly=True
for s in structs:
    print(f"{s.name} ({s.property_count} properties)")

# Get detailed enum info — returns a single EnumInfo (or None), NOT a (success, info) tuple
enum_info = unreal.EnumStructService.get_enum_info("EWeaponType")
if enum_info:
    for v in enum_info.values:
        print(f"  {v.name} = {v.value} ({v.display_name})")

Modify Existing Enum

import unreal

enum_path = "/Game/Data/Enums/EWeaponType.EWeaponType"

# Rename a value
unreal.EnumStructService.rename_enum_value(enum_path, "Sword", "LongSword")

# Change display name
unreal.EnumStructService.set_enum_value_display_name(enum_path, "Bow", "Composite Bow")

# Remove a value
unreal.EnumStructService.remove_enum_value(enum_path, "Staff")

# Add new value
unreal.EnumStructService.add_enum_value(enum_path, "Crossbow", "Heavy Crossbow")

Modify Existing Struct

import unreal

struct_path = "/Game/Data/Structs/FWeaponData.FWeaponData"

# Rename a property
unreal.EnumStructService.rename_struct_property(struct_path, "Damage", "BaseDamage")

# Change property type — ⚠️ this RESETS the default value to the new type's zero;
# re-set the default afterwards if you need one
unreal.EnumStructService.change_struct_property_type(struct_path, "BaseDamage", "int32")

# Set default value
unreal.EnumStructService.set_struct_property_default(struct_path, "BaseDamage", "15")

# Remove a property
unreal.EnumStructService.remove_struct_property(struct_path, "SpecialEffects")

# Add new property
unreal.EnumStructService.add_struct_property(struct_path, "CriticalMultiplier", "float", "2.0")

Use Struct in a DataTable

After creating a UserDefinedStruct, it becomes available as a DataTable row type. The struct must contain at least one property before it can be used as a row type.

import unreal

# Create the row struct with EnumStructService
struct_path = unreal.EnumStructService.create_struct("/Game/Data", "ItemRow")
unreal.EnumStructService.add_struct_property(struct_path, "ItemName", "FString")
unreal.EnumStructService.add_struct_property(struct_path, "Value", "int32", "0")
unreal.EnumStructService.add_struct_property(struct_path, "Icon", "UTexture2D")

DataTable creation itself is no longer a VibeUE service — it is owned by the engine's native asset toolset. Create the DataTable with the engine AssetTools toolset via call_tool (pass the FItemRow struct as the row structure); run describe_toolset on AssetTools for the exact action name and parameters. You can also create one in raw Python via unreal.AssetToolsHelpers + unreal.DataTableFactory if you prefer execute_python_code.

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Available Property Types

When adding struct properties, use these type strings:

Basic Types

• bool, int32, int64, float, double
• FString, FName, FText, uint8, byte

Common Structs

• FVector, FVector2D, FRotator, FTransform
• FColor, FLinearColor
• FGameplayTag, FGameplayTagContainer

Object References

• AActor, APawn, ACharacter
• UTexture2D, UMaterial, UStaticMesh
• USoundBase, UAnimSequence

Containers

Use the ContainerType parameter:

# Array of strings
unreal.EnumStructService.add_struct_property(path, "Tags", "FString", "", "Array")

# Set of names
unreal.EnumStructService.add_struct_property(path, "UniqueNames", "FName", "", "Set")

# Map of string to int
unreal.EnumStructService.add_struct_property(path, "Scores", "int32", "", "Map")

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Troubleshooting

"Enum not found" Error

• Check if using full path vs just name
• Use search_enums() to find the correct path
• Ensure the asset is saved

"Cannot modify native enum/struct"

• Only UserDefinedEnum/UserDefinedStruct assets can be modified
• Native C++ types from engine/plugins are read-only
• Check is_user_defined property before modifying

Property Type Not Recognized

• Use BlueprintService.search_variable_types() to find valid type names
• Ensure enum/struct types exist before referencing them

Sample scripts (run via execute_python_code)

• scripts/create_enum_struct.txt — create a UserDefinedEnum (+values) and a UserDefinedStruct.