Add editing of variable defaults to BlueprrintVariable functions.

Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/BlueprintVariable_Create.h

@@ -69,7 +69,7 @@ public:
 		// Apply config if provided
 		if (Config.Json && Config.Json->Values.Num() > 0)
 		{
-			if (!Editor.LoadJson(Config.Json.Get()))
+			if (!Editor.ApplyJson(Config.Json.Get()))
 				return;
 		}
 

Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/BlueprintVariable_Modify.h

@@ -53,7 +53,7 @@ public:
 			return;
 		}
 
-		if (!Editor.LoadJson(Properties.Json.Get()))
+		if (!Editor.ApplyJson(Properties.Json.Get()))
 			return;
 
 		UMCPServer::Printf(TEXT("Modified variable %s (%s) in %s\n"),

Plugins/BlueprintMCP/Source/BlueprintMCP/Private/BPVarEditor.cpp

@@ -16,11 +16,21 @@ FBPVarEditor::FBPVarEditor(UBlueprint* BP, const FString& VarName)
 		return;
 	}
 	Desc = &BP->NewVariables[VarIndex];
+
+	// Try to find the default value property on the CDO.
+	if (BP->GeneratedClass)
+	{
+		UObject* CDO = BP->GeneratedClass->GetDefaultObject();
+		FProperty* Prop = BP->GeneratedClass->FindPropertyByName(VarFName);
+		if (CDO && Prop)
+			DefaultValueProp = MCPProperty(Prop, CDO);
+	}
 }
 
 void FBPVarEditor::Dump()
 {
-	Load();
+	LoadFlags();
+	LoadDefault();
 	TArray<MCPProperty> Props = MergedProperties();
 	for (MCPProperty& P : Props)
 	{
@@ -31,17 +41,22 @@ void FBPVarEditor::Dump()
 	}
 }
 
-bool FBPVarEditor::LoadJson(const FJsonObject* Json)
+bool FBPVarEditor::ApplyJson(const FJsonObject* Json)
 {
-	Load();
+	LoadFlags();
+	bool bHasDefault = Json->HasField(TEXT("DefaultValue"));
+
 	TArray<MCPProperty> Props = MergedProperties();
 	if (!MCPJson::PopulateFromJson(Props, Json, true))
 		return false;
-	Save();
+
+	SaveFlags();
+	if (bHasDefault)
+		return SaveDefault();
 	return true;
 }
 
-void FBPVarEditor::Load()
+void FBPVarEditor::LoadFlags()
 {
 	InstanceEditable   = !(Desc->PropertyFlags & CPF_DisableEditOnInstance);
 	BlueprintReadOnly  =  (Desc->PropertyFlags & CPF_BlueprintReadOnly) != 0;
@@ -49,14 +64,21 @@ void FBPVarEditor::Load()
 	ExposeOnSpawn      = Desc->HasMetaData(FBlueprintMetadata::MD_ExposeOnSpawn);
 	Private            = Desc->HasMetaData(FBlueprintMetadata::MD_Private);
 
-	FString Tooltip;
 	if (Desc->HasMetaData(TEXT("tooltip")))
 		Description = Desc->GetMetaData(TEXT("tooltip"));
 	else
 		Description.Empty();
 }
 
-void FBPVarEditor::Save() const
+void FBPVarEditor::LoadDefault()
+{
+	if (DefaultValueProp)
+		DefaultValue = DefaultValueProp.GetText();
+	else
+		DefaultValue.Empty();
+}
+
+void FBPVarEditor::SaveFlags()
 {
 	// CPF flags
 	if (InstanceEditable)
@@ -92,6 +114,13 @@ void FBPVarEditor::Save() const
 		Desc->RemoveMetaData(TEXT("tooltip"));
 }
 
+bool FBPVarEditor::SaveDefault()
+{
+	if (DefaultValueProp)
+		return DefaultValueProp.SetText(DefaultValue);
+	return true;
+}
+
 TArray<MCPProperty> FBPVarEditor::MergedProperties()
 {
 	TArray<MCPProperty> Props = MCPProperty::GetAll(
@@ -106,5 +135,9 @@ TArray<MCPProperty> FBPVarEditor::MergedProperties()
 	Props.Append(MCPProperty::GetAll(
 		FBPVarEditor::StaticStruct(), this, (EPropertyFlags)0));
 
+	// Remove DefaultValue if we don't have a CDO property to back it.
+	if (!DefaultValueProp)
+		MCPProperty::Remove(Props, TEXT("DefaultValue"));
+
 	return Props;
 }

Plugins/BlueprintMCP/Source/BlueprintMCP/Public/BPVarEditor.h

@@ -15,13 +15,16 @@ struct FBPVarEditor
 	GENERATED_BODY()
 
 	FBPVariableDescription* Desc = nullptr;
+	MCPProperty DefaultValueProp;
 
 	FBPVarEditor() = default;
-	FBPVarEditor(FBPVariableDescription* InDesc) : Desc(InDesc) {}
 	FBPVarEditor(UBlueprint* BP, const FString& VarName);
 
 	bool NotFound() const { return Desc == nullptr; }
 
+	UPROPERTY(EditAnywhere, meta=(Optional, Description="Default value in Unreal text format"))
+	FString DefaultValue;
+
 	UPROPERTY(EditAnywhere, meta=(Optional, Description="Variable description/tooltip"))
 	FString Description;
 
@@ -41,13 +44,15 @@ struct FBPVarEditor
 	bool ExposeToCinematics = false;
 
 	// Load from Desc, populate from JSON, save back to Desc.
-	bool LoadJson(const FJsonObject* Json);
+	bool ApplyJson(const FJsonObject* Json);
 
 	// Print all properties and their current values.
 	void Dump();
 
 private:
-	void Load();
-	void Save() const;
+	void LoadFlags();
+	void LoadDefault();
+	void SaveFlags();
+	bool SaveDefault();
 	TArray<MCPProperty> MergedProperties();
 };