Metadata Specifiers

When declaring classes, interfaces, structs, enums, enum values, functions, or properties, you can add Metadata Specifiers to control how they interact with various aspects of the engine and editor. Each type of data structure or member has its own list of Metadata Specifiers.

Metadata only exists in the editor; do not write game logic that accesses metadata.

To add Metadata Specifiers, use the word meta, followed by a list of the specifiers and, if appropriate, their values, to your UCLASS, UENUM, UINTERFACE, USTRUCT, UFUNCTION, or UPROPERTY macro, as follows:

	{UCLASS/UENUM/UINTERFACE/USTRUCT/UFUNCTION/UPROPERTY}(SpecifierX, meta=(MetaTag1="Value1", MetaTag2, ..), SpecifierY)
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{UCLASS/UENUM/UINTERFACE/USTRUCT/UFUNCTION/UPROPERTY}(SpecifierX, meta=(MetaTag1="Value1", MetaTag2, ..), SpecifierY)

To add Metadata Specifiers to a specific value within an enumerated type, add the UMETA tag to the value itself before the separating comma (if one exists). It should look like:

	UENUM()
	enum class EMyEnum : uint8
	{
		// DefaultValue Tooltip
		DefaultValue = 0 UMETA(MetaTag1="Value1", MetaTag2, ..),

		// ValueWithoutMetaSpecifiers Tooltip
		ValueWithoutMetaSpecifiers,

		// ValueWithMetaSpecifiers Tooltip
		ValueWithMetaSpecifiers UMETA((MetaTag1="Value1", MetaTag2, ..),

		// FinalValue Tooltip
		FinalValue (MetaTag1="Value1", MetaTag2, ..)
	};
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UENUM() enum class EMyEnum : uint8 { // DefaultValue Tooltip DefaultValue = 0 UMETA(MetaTag1="Value1", MetaTag2, ..), // ValueWithoutMetaSpecifiers Tooltip ValueWithoutMetaSpecifiers, // ValueWithMetaSpecifiers Tooltip ValueWithMetaSpecifiers UMETA((MetaTag1="Value1", MetaTag2, ..), // FinalValue Tooltip FinalValue (MetaTag1="Value1", MetaTag2, ..) };

Class Metadata Specifiers

Classes can use the following Metatag Specifiers:

| Class Meta Tag | Effect | | --- | --- | | BlueprintSpawnableComponent | If present, the component Class can be spawned by a Blueprint. | | BlueprintThreadSafe | Only valid on Blueprint function libraries. This specifier marks the functions in this class as callable on non-game threads in animation Blueprints. | | ChildCannotTick | Used for Actor and Component classes. If the native class cannot tick, Blueprint-generated classes based this Actor or Component can never tick, even if bCanBlueprintsTickByDefault is true. | | ChildCanTick | Used for Actor and Component classes. If the native class cannot tick, Blueprint-generated classes based this Actor or Component can have the bCanEverTick flag overridden, even if bCanBlueprintsTickByDefault is false. | | DeprecatedNode | For behavior tree nodes, indicates that the class is deprecated and will display a warning when compiled. | | DeprecationMessage="Message Text" | Deprecated classes with this metadata will include this text with the standard deprecation warning that Blueprint Scripts generate during compilation. | | DisplayName="Blueprint Node Name" | The name of this node in a Blueprint Script will be replaced with the value provided here, instead of the code-generated name. | | DontUseGenericSpawnObject | Do not spawn an Object of the class using Generic Create Object node in Blueprint Scripts; this specifier applies only to Blueprint-type classes that are neither Actors nor Actor Components. | | ExposedAsyncProxy | Expose a proxy Object of this class in Async Task nodes. | | IgnoreCategoryKeywordsInSubclasses | Used to make the first subclass of a class ignore all inherited ShowCategories and HideCategories Specifiers. | | IsBlueprintBase="true/false" | States that this class is (or is not) an acceptable base class for creating Blueprints, similar to the Blueprintable or 'NotBlueprintable` Specifiers. |

KismetHideOverrides="Event1, Event2, .."	List of Blueprint events that are not allowed to be overridden.
ProhibitedInterfaces="Interface1, Interface2, .."	Lists Interfaces that are not compatible with the class.
RestrictedToClasses="Class1, Class2, .."	Blueprint function library classes can use this to restrict usage to the classes named in the list.
ShortToolTip="Short tooltip"	A short tooltip that is used in some contexts where the full tooltip might be overwhelming, such as the Parent Class Picker dialog.
ShowWorldContextPin	Indicates that Blueprint nodes placed in graphs owned by this class must show their World context pins, even if they are normally hidden, because Objects of this class cannot be used as World context.
UsesHierarchy	Indicates the class uses hierarchical data. Used to instantiate hierarchical editing features in Details panels.
ToolTip="Hand-written tooltip"	Overrides the automatically generated tooltip from code comments.

Enum Metadata Specifiers

Enumerated types can use the following Metadata Specifiers:

Individual values within an enumerated type have their own Metadata Specifiers. These differ slightly from other Metadata Specifiers in that they use top-level keyword UMETA, and are specified after the value they modify, rather than before.

Interface Metadata Specifiers

Interfaces can use the following Metatag Specifier:

Ensure that Blueprint events are only allowed in implementable interfaces. Internal only functions allowed Ensure that if this interface contains Blueprint callable functions that are not Blueprint defined, that it must be implemented natively

Interface Meta Tag	Effect
CannotImplementInterfaceInBlueprint	This interface may not contain BlueprintImplementableEvent or BlueprintNativeEvent functions, other than internal-only functions. If it contains Blueprint-callable functions that are not blueprint-defined, those functions must be implemented in native code.

Struct Metadata Specifiers

Structs can use the following Metatag Specifiers:

Struct Meta Tag	Effect
HasNativeBreak="Module.Class.Function"	Indicates that this struct has a custom Break Struct node. The module, class, and function name must be provided.
HasNativeMake="Module.Class.Function"	Indicates that this struct has a custom Make Struct node. The module, class, and function name must be provided.
HiddenByDefault	Pins in Make Struct and Break Struct nodes are hidden by default.
ShortToolTip="Short tooltip"	A short tooltip that is used in some contexts where the full tooltip might be overwhelming, such as the Parent Class Picker dialog.
ToolTip="Hand-written tooltip	Overrides the automatically generated tooltip from code comments.

Function Metadata Specifiers

Function Meta Tag	Effect
AdvancedDisplay="Parameter1, Parameter2, .."	The comma-separated list of parameters will show up as advanced pins (requiring UI expansion).
AdvancedDisplay=N	Replace N with a number, and all parameters after the Nth will show up as advanced pins (requiring UI expansion). For example, 'AdvancedDisplay=2' will mark all but the first two parameters as advanced).
ArrayParm="Parameter1, Parameter2, .."	Indicates that a BlueprintCallable function should use a Call Array Function node and that the listed parameters should be treated as wild card array properties.
ArrayTypeDependentParams="Parameter"	When ArrayParm is used, this specifier indicates one parameter which will determine the types of all parameters in the ArrayParm list.
AutoCreateRefTerm="Parameter1, Parameter2, .."	The listed parameters, although passed by reference, will have an automatically created default if their pins are left disconnected. This is a convenience feature for Blueprints, often used on array pins.
BlueprintAutocast	Used only by static BlueprintPure functions from a Blueprint function library. A cast node will be automatically added for the return type and the type of the first parameter of the function.
BlueprintInternalUseOnly	This function is an internal implementation detail, used to implement another function or node. It is never directly exposed in a Blueprint graph.
BlueprintProtected	This function can only be called on the owning Object in a Blueprint. It cannot be called on another instance.
CallableWithoutWorldContext	Used for BlueprintCallable functions that have a WorldContext pin to indicate that the function can be called even if its Class does not implement the GetWorld function.
CommutativeAssociativeBinaryOperator	Indicates that a BlueprintCallable function should use the Commutative Associative Binary node. This node lacks pin names, but features an Add Pin button that creates additional input pins.
CompactNodeTitle="Name"	Indicates that a BlueprintCallable function should display in the compact display mode, and provides the name to display in that mode.
CustomStructureParam="Parameter1, Parameter2, .."	The listed parameters are all treated as wildcards. This specifier requires the UFUNCTION-level specifier, CustomThunk, which will require the user to provide a custom exec function. In this function, the parameter types can be checked and the appropriate function calls can be made based on those parameter types. The base UFUNCTION should never be called, and should assert or log an error if it is. To declare a custom exec function, use the syntax DECLARE_FUNCTION(execMyFunctionName) where MyFunctionName is the name of the original function.
DefaultToSelf	For BlueprintCallable functions, this indicates that the Object property's named default value should be the self context of the node.
DeprecatedFunction	Any Blueprint references to this function will cause compilation warnings telling the user that the function is deprecated. You can add to the deprecation warning message (for example, to provide instructions on replacing the deprecated function) using the DeprecationMessage metadata specifier.
DeprecationMessage="Message Text"	If the function is deprecated, this message will be added to the standard deprecation warning when trying to compile a Blueprint that uses it.
DeterminesOutputType="Parameter"	The return type of the function will dynamically change to match the input that is connected to the named parameter pin. The parameter should be a templated type like TSubClassOf<X> or TSoftObjectPtr<X>, where the function's original return type is X* or a container with X* as the value type, such as TArray<X*>.
DevelopmentOnly	Functions marked as DevelopmentOnly will only run in Development mode. This is useful for functionality like debug output, which is expected not to exist in shipped products.
DisplayName="Blueprint Node Name"	The name of this node in a Blueprint will be replaced with the value provided here, instead of the code-generated name.
ExpandEnumAsExecs="Parameter"	For BlueprintCallable functions, this indicates that one input execution pin should be created for each entry in the enum used by the parameter. The parameter must be of an enumerated type that has the UENUM tag.
HidePin="Parameter"	For BlueprintCallable functions, this indicates that the parameter pin should be hidden from the user's view. Only one pin per function can be hidden in this manner.
HideSelfPin	Hides the "self" pin, which indicates the object on which the function is being called. The "self" pin is automatically hidden on BlueprintPure functions that are compatible with the calling Blueprint's Class. Functions that use the HideSelfPin Meta Tag frequently also use the DefaultToSelf Specifier.
InternalUseParam="Parameter"	Similar to HidePin, this hides the named parameter's pin from the user's view, and can only be used for one parameter per function.
KeyWords="Set Of Keywords"	Specifies a set of keywords that can be used when searching for this function, such as when placing a node to call the function in a Blueprint Graph.
Latent	Indicates a latent action. Latent actions have one parameter of type FLatentActionInfo, and this parameter is named by the LatentInfo specifier.
LatentInfo="Parameter"	For Latent BlueprintCallable functions indicates which parameter is the LatentInfo parameter.
MaterialParameterCollectionFunction	For BlueprintCallable functions, indicates that the material override node should be used.
NativeBreakFunc	For BlueprintCallable functions, indicates that the function should be displayed the same way as a standard Break Struct node.
NotBlueprintThreadSafe	Only valid in Blueprint function libraries. This function will be treated as an exception to the owning Class's general BlueprintThreadSafe metadata.
ShortToolTip="Short tooltip"	A short tooltip that is used in some contexts where the full tooltip might be overwhelming, such as the Parent Class Picker dialog.
ToolTip="Hand-written tooltip	Overrides the automatically generated tooltip from code comments.
UnsafeDuringActorConstruction	This function is not safe to call during Actor construction.
WorldContext="Parameter"	Used by BlueprintCallable functions to indicate which parameter determines the World in which the operation takes place.

Property Metadata Specifiers

Property Meta Tag	Effect
AllowAbstract="true/false"	Used for Subclass and SoftClass properties. Indicates whether abstract Class types should be shown in the Class picker.
AllowedClasses="Class1, Class2, .."	Used for FSoftObjectPath properties. Comma delimited list that indicates the Class type(s) of assets to be displayed in the Asset picker.
AllowPreserveRatio	Used for FVector properties. It causes a ratio lock to be added when displaying this property in details panels.
ArrayClamp="ArrayProperty"	Used for integer properties. Clamps the valid values that can be entered in the UI to be between 0 and the length of the array property named.
AssetBundles	Used for SoftObjectPtr or SoftObjectPath properties. List of Bundle names used inside Primary Data Assets to specify which Bundles this reference is part of.
BlueprintBaseOnly	Used for Subclass and SoftClass properties. Indicates whether only Blueprint Classes should be shown in the Class picker.
BlueprintCompilerGeneratedDefaults	Property defaults are generated by the Blueprint compiler and will not be copied when the CopyPropertiesForUnrelatedObjects function is called post-compile.
ClampMin="N"	Used for float and integer properties. Specifies the minimum value N that may be entered for the property.
ClampMax="N"	Used for float and integer properties. Specifies the maximum value N that may be entered for the property.
ConfigHierarchyEditable	This property is serialized to a config (.ini) file, and can be set anywhere in the config hierarchy.
ContentDir	Used by FDirectoryPath properties. Indicates that the path will be picked using the Slate-style directory picker inside the Content folder.
DisplayAfter="PropertyName"	This property will show up in the Blueprint Editor immediately after the property named PropertyName, regardless of its order in source code, as long as both properties are in the same category. If multiple properties have the same DisplayAfter value and the same DisplayPriority value, they will appear after the named property in the order in which they are declared in the header file.
DisplayName="Property Name"	The name to display for this property, instead of the code-generated name.
DisplayPriority="N"	If two properties feature the same DisplayAfter value, or are in the same category and do not have the DisplayAfter Meta Tag, this property will determine their sorting order. The highest-priority value is 1, meaning that a property with a DisplayPriority value of 1 will appear above a property with a DisplayProirity value of 2. If multiple properties have the same DisplayAfter value, they will appear in the order in which they are declared in the header file.
DisplayThumbnail="true"	Indicates that the property is an Asset type and it should display the thumbnail of the selected Asset.
EditCondition="BooleanPropertyName"	Names a boolean property that is used to indicate whether editing of this property is disabled. Putting "!" before the property name inverts the test. The EditCondition meta tag is no longer limited to a single boolean property. It is now evaluated using a full-fledged expression parser, meaning you can include a full C++ expression.
EditFixedOrder	Keeps the elements of an array from being reordered by dragging.
ExactClass="true"	Used for FSoftObjectPath properties in conjunction with AllowedClasses. Indicates whether only the exact Classes specified in AllowedClasses can be used, or if subclasses are also valid.
ExposeFunctionCategories="Category1, Category2, .."	Specifies a list of categories whose functions should be exposed when building a function list in the Blueprint Editor.
ExposeOnSpawn="true"	Specifies whether the property should be exposed on a Spawn Actor node for this Class type.
FilePathFilter="FileType"	Used by FFilePath properties. Indicates the path filter to display in the file picker. Common values include "uasset" and "umap", but these are not the only possible values.
GetByRef	Makes the "Get" Blueprint Node for this property return a const reference to the property instead of a copy of its value. Only usable with Sparse Class Data, and only when NoGetter is not present.
HideAlphaChannel	Used for FColor and FLinearColor properties. Indicates that the Alpha property should be hidden when displaying the property widget in the details.
HideViewOptions	Used for Subclass and SoftClass properties. Hides the ability to change view options in the Class picker.
InlineEditConditionToggle	Signifies that the boolean property is only displayed inline as an edit condition toggle in other properties, and should not be shown on its own row.
LongPackageName	Used by FDirectoryPath properties. Converts the path to a long package name.
MakeEditWidget	Used for Transform or Rotator properties, or Arrays of Transforms or Rotators. Indicates that the property should be exposed in the viewport as a movable widget.
NoGetter	Causes Blueprint generation not to generate a "get" Node for this property. Only usable with Sparse Class Data.