More work on handlers

Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/AnimBlueprint_SetBlendSpaceSamples.h

@@ -83,12 +83,12 @@ public:
 		FBlendParameter& MutableParamY = const_cast<FBlendParameter&>(ParamY);
 
 		if (!AxisXName.IsEmpty()) MutableParamX.DisplayName = AxisXName;
-		if (Json->HasField(TEXT("axisXMin"))) MutableParamX.Min = AxisXMin;
+		if (AxisXMin != 0.0f) MutableParamX.Min = AxisXMin;
-		if (Json->HasField(TEXT("axisXMax"))) MutableParamX.Max = AxisXMax;
+		if (AxisXMax != 0.0f) MutableParamX.Max = AxisXMax;
 
 		if (!AxisYName.IsEmpty()) MutableParamY.DisplayName = AxisYName;
-		if (Json->HasField(TEXT("axisYMin"))) MutableParamY.Min = AxisYMin;
+		if (AxisYMin != 0.0f) MutableParamY.Min = AxisYMin;
-		if (Json->HasField(TEXT("axisYMax"))) MutableParamY.Max = AxisYMax;
+		if (AxisYMax != 0.0f) MutableParamY.Max = AxisYMax;
 
 		// Clear existing samples (delete from end to start)
 		int32 NumExisting = BS->GetNumberOfBlendSamples();

Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/Material_Create.h

@@ -82,8 +82,6 @@ public:
 		}
 
 		// Apply optional properties.
-		bool bHasTwoSided = Json->HasField(TEXT("twoSided"));
-
 		TArray<UObject*> Chain = { MaterialObj };
 		MCPUtils::PreEdit(Chain);
 
@@ -93,8 +91,7 @@ public:
 		if (!BlendMode.IsEmpty())
 			MaterialObj->BlendMode = ParsedBlendMode;
 
-		if (bHasTwoSided)
+		MaterialObj->TwoSided = TwoSided ? 1 : 0;
-			MaterialObj->TwoSided = TwoSided;
 
 		MCPUtils::PostEdit(Chain);
 

Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/Material_DumpProperties.h

@@ -0,0 +1,48 @@
+#pragma once
+
+#include "CoreMinimal.h"
+#include "MCPHandler.h"
+#include "MCPFetcher.h"
+#include "MCPUtils.h"
+#include "Materials/Material.h"
+#include "MaterialDomain.h"
+#include "Material_DumpProperties.generated.h"
+
+
+// ---------------------------------------------------------------------------
+// ---------------------------------------------------------------------------
+// ---------------------------------------------------------------------------
+
+UCLASS()
+class UMCP_Material_DumpProperties : public UObject, public IMCPHandler
+{
+	GENERATED_BODY()
+
+public:
+	UPROPERTY(meta=(Description="Material path"))
+	FString Path;
+
+	virtual FString GetDescription() const override
+	{
+		return TEXT("List top-level material properties such as domain, blend mode, shading model, and usage flags.");
+	}
+
+	virtual void Handle(const FJsonObject* Json, FStringBuilderBase& Result) override
+	{
+		MCPFetcher F(Result);
+		UMaterial* Mat = F.Asset(Path).Cast<UMaterial>();
+		if (!Mat) return;
+
+		Result.Appendf(TEXT("Material: %s\n"), *MCPUtils::FormatName(Mat));
+		Result.Appendf(TEXT("  domain = %s\n"), *MCPUtils::EnumToString(Mat->MaterialDomain, TEXT("MD_")));
+		Result.Appendf(TEXT("  blendMode = %s\n"), *MCPUtils::EnumToString(Mat->BlendMode, TEXT("BLEND_")));
+		Result.Appendf(TEXT("  shadingModel = %s\n"), *MCPUtils::EnumToString(Mat->GetShadingModels().GetFirstShadingModel(), TEXT("MSM_")));
+		Result.Appendf(TEXT("  opacityMaskClipValue = %g\n"), Mat->OpacityMaskClipValue);
+		Result.Appendf(TEXT("  twoSided = %s\n"), Mat->TwoSided ? TEXT("true") : TEXT("false"));
+		Result.Appendf(TEXT("  bUsedWithSkeletalMesh = %s\n"), Mat->bUsedWithSkeletalMesh ? TEXT("true") : TEXT("false"));
+		Result.Appendf(TEXT("  bUsedWithMorphTargets = %s\n"), Mat->bUsedWithMorphTargets ? TEXT("true") : TEXT("false"));
+		Result.Appendf(TEXT("  bUsedWithNiagaraSprites = %s\n"), Mat->bUsedWithNiagaraSprites ? TEXT("true") : TEXT("false"));
+		Result.Appendf(TEXT("  ditheredLODTransition = %s\n"), Mat->DitheredLODTransition ? TEXT("true") : TEXT("false"));
+		Result.Appendf(TEXT("  bAllowNegativeEmissiveColor = %s\n"), Mat->bAllowNegativeEmissiveColor ? TEXT("true") : TEXT("false"));
+	}
+};

Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/Material_SetProperty.h

@@ -2,7 +2,7 @@
 
 #include "CoreMinimal.h"
 #include "MCPHandler.h"
-#include "MCPAssetFinder.h"
+#include "MCPFetcher.h"
 #include "MCPUtils.h"
 #include "Materials/Material.h"
 #include "MaterialDomain.h"
@@ -19,102 +19,81 @@ class UMCP_Material_SetProperty : public UObject, public IMCPHandler
 	GENERATED_BODY()
 
 public:
-	UPROPERTY(meta=(Description="Material name or package path"))
+	UPROPERTY(meta=(Description="Material path"))
-	FString Material;
+	FString Path;
 
 	UPROPERTY(meta=(Description="Property name to set (domain, blendMode, twoSided, shadingModel, opacity, opacityMaskClipValue, bUsedWithSkeletalMesh, bUsedWithMorphTargets, bUsedWithNiagaraSprites, ditheredLODTransition, bAllowNegativeEmissiveColor)"))
 	FString Property;
 
-	UPROPERTY(meta=(Optional, Description="If true, preview the change without applying it"))
+	UPROPERTY(meta=(Description="Value to set"))
-	bool DryRun = false;
+	FString Value;
 
 	virtual FString GetDescription() const override
 	{
-		return TEXT("Set a top-level material property such as domain, blend mode, shading model, or usage flags. "
+		return TEXT("Set a top-level material property such as domain, blend mode, shading model, or usage flags.");
-			"The 'value' field in the JSON payload provides the new value.");
 	}
 
 	virtual void Handle(const FJsonObject* Json, FStringBuilderBase& Result) override
 	{
-		if (!Json->HasField(TEXT("value")))
+		MCPFetcher F(Result);
-		{
+		UMaterial* Mat = F.Asset(Path).Cast<UMaterial>();
-			Result.Append(TEXT("ERROR: Missing required field: value\n"));
+		if (!Mat) return;
-			return;
-		}
 
-		// Load material
+		// Parse value and build setter. Validation happens here so we can bail before PreEdit.
-		MCPAssets<UMaterial> Assets;
+		TFunction<void()> Setter;
-		if (!Assets.Exact(Material).Errors(Result).ENone().ETwo().Load()) return;
-		UMaterial* Mat = Assets.Object();
-
-		FString OldValue;
-		FString NewValue;
-
-		// Helper: apply a bool property change.
-		auto SetBool = [&](auto Getter, auto Setter) {
-			bool bValue = Json->GetBoolField(TEXT("value"));
-			OldValue = Getter() ? TEXT("true") : TEXT("false");
-			NewValue = bValue ? TEXT("true") : TEXT("false");
-			if (!DryRun) Setter(bValue);
-		};
 
 		if (Property == TEXT("domain"))
 		{
-			FString ValueStr = Json->GetStringField(TEXT("value"));
-			OldValue = MCPUtils::EnumToString(Mat->MaterialDomain, TEXT("MD_"));
 			EMaterialDomain NewDomain;
-			if (!MCPUtils::StringToEnum(ValueStr, NewDomain, Result, TEXT("MD_"))) return;
+			if (!MCPUtils::StringToEnum(Value, NewDomain, Result, TEXT("MD_"))) return;
-			NewValue = MCPUtils::EnumToString(NewDomain, TEXT("MD_"));
+			Setter = [Mat, NewDomain]() { Mat->MaterialDomain = NewDomain; };
-			if (!DryRun) Mat->MaterialDomain = NewDomain;
 		}
 		else if (Property == TEXT("blendMode"))
 		{
-			FString ValueStr = Json->GetStringField(TEXT("value"));
-			OldValue = MCPUtils::EnumToString(Mat->BlendMode, TEXT("BLEND_"));
 			EBlendMode NewBlend;
-			if (!MCPUtils::StringToEnum(ValueStr, NewBlend, Result, TEXT("BLEND_"))) return;
+			if (!MCPUtils::StringToEnum(Value, NewBlend, Result, TEXT("BLEND_"))) return;
-			NewValue = MCPUtils::EnumToString(NewBlend, TEXT("BLEND_"));
+			Setter = [Mat, NewBlend]() { Mat->BlendMode = NewBlend; };
-			if (!DryRun) Mat->BlendMode = NewBlend;
 		}
 		else if (Property == TEXT("shadingModel"))
 		{
-			FString ValueStr = Json->GetStringField(TEXT("value"));
-			OldValue = MCPUtils::EnumToString(Mat->GetShadingModels().GetFirstShadingModel(), TEXT("MSM_"));
 			EMaterialShadingModel NewModel;
-			if (!MCPUtils::StringToEnum(ValueStr, NewModel, Result, TEXT("MSM_"))) return;
+			if (!MCPUtils::StringToEnum(Value, NewModel, Result, TEXT("MSM_"))) return;
-			NewValue = MCPUtils::EnumToString(NewModel, TEXT("MSM_"));
+			Setter = [Mat, NewModel]() { Mat->SetShadingModel(NewModel); };
-			if (!DryRun) Mat->SetShadingModel(NewModel);
 		}
 		else if (Property == TEXT("opacity") || Property == TEXT("opacityMaskClipValue"))
 		{
-			double OpacityValue = Json->GetNumberField(TEXT("value"));
+			float FloatVal = FCString::Atof(*Value);
-			OldValue = FString::Printf(TEXT("%g"), Mat->OpacityMaskClipValue);
+			Setter = [Mat, FloatVal]() { Mat->OpacityMaskClipValue = FloatVal; };
-			NewValue = FString::Printf(TEXT("%g"), OpacityValue);
-			if (!DryRun) Mat->OpacityMaskClipValue = (float)OpacityValue;
 		}
 		else if (Property == TEXT("twoSided"))
 		{
-			SetBool([&]{ return Mat->TwoSided; }, [&](bool v){ Mat->TwoSided = v ? 1 : 0; });
+			bool bVal; if (!MCPUtils::StringToBool(Value, bVal, Result)) return;
+			Setter = [Mat, bVal]() { Mat->TwoSided = bVal ? 1 : 0; };
 		}
 		else if (Property == TEXT("bUsedWithSkeletalMesh"))
 		{
-			SetBool([&]{ return Mat->bUsedWithSkeletalMesh; }, [&](bool v){ Mat->bUsedWithSkeletalMesh = v ? 1 : 0; });
+			bool bVal; if (!MCPUtils::StringToBool(Value, bVal, Result)) return;
+			Setter = [Mat, bVal]() { Mat->bUsedWithSkeletalMesh = bVal ? 1 : 0; };
 		}
 		else if (Property == TEXT("bUsedWithMorphTargets"))
 		{
-			SetBool([&]{ return Mat->bUsedWithMorphTargets; }, [&](bool v){ Mat->bUsedWithMorphTargets = v ? 1 : 0; });
+			bool bVal; if (!MCPUtils::StringToBool(Value, bVal, Result)) return;
+			Setter = [Mat, bVal]() { Mat->bUsedWithMorphTargets = bVal ? 1 : 0; };
 		}
 		else if (Property == TEXT("bUsedWithNiagaraSprites"))
 		{
-			SetBool([&]{ return Mat->bUsedWithNiagaraSprites; }, [&](bool v){ Mat->bUsedWithNiagaraSprites = v ? 1 : 0; });
+			bool bVal; if (!MCPUtils::StringToBool(Value, bVal, Result)) return;
+			Setter = [Mat, bVal]() { Mat->bUsedWithNiagaraSprites = bVal ? 1 : 0; };
 		}
 		else if (Property == TEXT("ditheredLODTransition") || Property == TEXT("DitheredLODTransition"))
 		{
-			SetBool([&]{ return Mat->DitheredLODTransition; }, [&](bool v){ Mat->DitheredLODTransition = v ? 1 : 0; });
+			bool bVal; if (!MCPUtils::StringToBool(Value, bVal, Result)) return;
+			Setter = [Mat, bVal]() { Mat->DitheredLODTransition = bVal ? 1 : 0; };
 		}
 		else if (Property == TEXT("bAllowNegativeEmissiveColor"))
 		{
-			SetBool([&]{ return Mat->bAllowNegativeEmissiveColor; }, [&](bool v){ Mat->bAllowNegativeEmissiveColor = v ? 1 : 0; });
+			bool bVal; if (!MCPUtils::StringToBool(Value, bVal, Result)) return;
+			Setter = [Mat, bVal]() { Mat->bAllowNegativeEmissiveColor = bVal ? 1 : 0; };
 		}
 		else
 		{
@@ -124,18 +103,12 @@ public:
 			return;
 		}
 
-		// Notify and save if not dry run
+		// Apply the change between PreEdit/PostEdit.
-		if (!DryRun)
+		F.PreEdit();
-		{
+		Setter();
-			TArray<UObject*> Chain = { Mat };
+		F.PostEdit();
-			MCPUtils::PreEdit(Chain);
+		MCPUtils::SaveMaterialPackage(Mat);
-			MCPUtils::PostEdit(Chain);
-			if (!MCPUtils::SaveMaterialPackage(Mat))
-				Result.Append(TEXT("WARNING: Package save failed\n"));
-		}
 
-		Result.Appendf(TEXT("%s%s: %s -> %s\n"),
+		Result.Appendf(TEXT("Set %s on %s\n"), *Property, *MCPUtils::FormatName(Mat));
-			DryRun ? TEXT("[DRY RUN] ") : TEXT(""),
-			*Property, *OldValue, *NewValue);
 	}
 };

Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/StateMachine_AddTransition.h

@@ -84,18 +84,9 @@ public:
 		TransNode->CreateConnections(FromStateNode, ToStateNode);
 
 		// Set optional properties
-		if (Json->HasField(TEXT("crossfadeDuration")))
-		{
 		TransNode->CrossfadeDuration = CrossfadeDuration;
-		}
-		if (Json->HasField(TEXT("priority")))
-		{
 		TransNode->PriorityOrder = Priority;
-		}
-		if (Json->HasField(TEXT("bBidirectional")))
-		{
 		TransNode->Bidirectional = BBidirectional;
-		}
 
 		// Compile and save
 		FKismetEditorUtilities::CompileBlueprint(AnimBP);

Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/StateMachine_SetTransitionRule.h

@@ -74,40 +74,12 @@ public:
 			return;
 		}
 
-		// Count and apply property changes
+		// Apply properties
-		int32 ChangedCount = 0;
-
-		if (Json->HasField(TEXT("crossfadeDuration")))
-		{
 		TransNode->CrossfadeDuration = CrossfadeDuration;
-			ChangedCount++;
-		}
-		if (Json->HasField(TEXT("blendMode")))
-		{
 		TransNode->BlendMode = (EAlphaBlendOption)BlendMode;
-			ChangedCount++;
-		}
-		if (Json->HasField(TEXT("priorityOrder")))
-		{
 		TransNode->PriorityOrder = PriorityOrder;
-			ChangedCount++;
-		}
-		if (Json->HasField(TEXT("logicType")))
-		{
 		TransNode->LogicType = (ETransitionLogicType::Type)LogicType;
-			ChangedCount++;
-		}
-		if (Json->HasField(TEXT("bBidirectional")))
-		{
 		TransNode->Bidirectional = BBidirectional;
-			ChangedCount++;
-		}
-
-		if (ChangedCount == 0)
-		{
-			Result.Append(TEXT("ERROR: No properties to update. Provide at least one of: crossfadeDuration, blendMode, priorityOrder, logicType, bBidirectional\n"));
-			return;
-		}
 
 		TArray<UObject*> Chain = { TransNode };
 		MCPUtils::PreEdit(Chain);
@@ -117,7 +89,7 @@ public:
 		FKismetEditorUtilities::CompileBlueprint(AnimBP);
 		MCPUtils::SaveBlueprintPackage(AnimBP);
 
-		Result.Appendf(TEXT("Updated %d properties on transition %s -> %s: %s\n"),
+		Result.Appendf(TEXT("Updated transition %s -> %s: %s\n"),
-			ChangedCount, *FromState, *ToState, *MCPUtils::FormatName(TransNode));
+			*FromState, *ToState, *MCPUtils::FormatName(TransNode));
 	}
 };

Plugins/BlueprintMCP/Source/BlueprintMCP/Public/MCPUtils.h

@@ -218,6 +218,14 @@ public:
 		return true;
 	}
 
+	static bool StringToBool(const FString& Str, bool& OutValue, MCPErrorCallback Error)
+	{
+		if (Str.Equals(TEXT("true"), ESearchCase::IgnoreCase))  { OutValue = true;  return true; }
+		if (Str.Equals(TEXT("false"), ESearchCase::IgnoreCase)) { OutValue = false; return true; }
+		Error.SetError(FString::Printf(TEXT("Invalid bool value '%s' (expected 'true' or 'false')"), *Str));
+		return false;
+	}
+
 	// ----- Blueprint helpers -----
 	static TArray<UEdGraph*> AllGraphs(UBlueprint* BP);
 	static TArray<UEdGraph*> AllGraphsNamed(UBlueprint* BP, const FString& Name);