Fix: Prevent infinite loop when serializing assets with reflection types #296
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Filter out System.Reflection types (RuntimeType, RuntimeModule, RuntimeAssembly) from serialization to prevent circular references causing OutOfMemoryException when reading assets with AssetReferences. Reflection metadata cannot be meaningfully serialized to JSON or reconstructed, so excluding it improves both stability and output quality for read/write operations.
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Pull Request Overview
This PR fixes an infinite recursion bug in the Unity MCP Plugin's serialization system that occurred when serializing Unity assets containing System.Reflection types. The fix prevents OutOfMemoryException crashes by filtering out reflection metadata types (RuntimeType, RuntimeModule, RuntimeAssembly, etc.) from serialization, as these types form circular reference chains and provide no useful information for AI analysis.
Key changes:
- Added
IsReflectionType()helper method to identify and filter System.Reflection namespace types - Applied reflection type filtering to both field and property serialization in converter classes
- Added null-check guard when adding components to prevent silent failures
Reviewed Changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| UnityGenericReflectionConvertor.cs | Implements reflection type filtering in GetSerializableFields() and GetSerializableProperties() with new IsReflectionType() helper |
| UnityArrayReflectionConvertor.cs | Applies identical reflection type filtering logic to array converter |
| GameObject.AddComponent.cs | Adds null-check validation after AddComponent() to warn about failures |
...-MCP-Plugin/Assets/root/Runtime/ReflectionConverters/Base/UnityGenericReflectionConvertor.cs
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...-MCP-Plugin/Assets/root/Runtime/ReflectionConverters/Base/UnityGenericReflectionConvertor.cs
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I've addressed feedback issues |
| // Catch System.Reflection.* namespace types | ||
| // Note: System.RuntimeType and System.Type are in System namespace, not System.Reflection | ||
| return fullName.StartsWith("System.Reflection.") || | ||
| fullName == "System.RuntimeType" || |
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Change it to type comparison instead of string comparison
type == typeof(System.RuntimeType)
type == typeof(System.Type)There was a problem hiding this comment.
System.RuntimeType is not a real type
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| // Catch System.Reflection.* namespace types | ||
| // Note: System.RuntimeType and System.Type are in System namespace, not System.Reflection | ||
| return fullName.StartsWith("System.Reflection.") || |
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I am not sure sure about ignoring entire namespace System.Reflection.*. Any purposes of this?
| .Where(field => field.IsPublic || field.IsPrivate && field.GetCustomAttribute<SerializeField>() != null) | ||
| .Where(field => !ReflectionTypeFilter.IsReflectionType(field.FieldType)); | ||
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| public override IEnumerable<PropertyInfo>? GetSerializableProperties(Reflector reflector, Type objType, BindingFlags flags, ILogger? logger = null) | ||
| { | ||
| var baseProperties = base.GetSerializableProperties(reflector, objType, flags, logger); | ||
| if (baseProperties == null) return null; | ||
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| return baseProperties.Where(prop => !ReflectionTypeFilter.IsReflectionType(prop.PropertyType)); | ||
| } |
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We don't need to do it in this class. Need to take care of the problematic types globally by making a custom ReflectionConvertors for that type.
| .Where(field => field.IsPublic || field.IsPrivate && field.GetCustomAttribute<SerializeField>() != null) | ||
| .Where(field => !ReflectionTypeFilter.IsReflectionType(field.FieldType)); | ||
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| public override IEnumerable<PropertyInfo>? GetSerializableProperties(Reflector reflector, Type objType, BindingFlags flags, ILogger? logger = null) | ||
| { | ||
| var baseProperties = base.GetSerializableProperties(reflector, objType, flags, logger); | ||
| if (baseProperties == null) return null; | ||
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| return baseProperties.Where(prop => !ReflectionTypeFilter.IsReflectionType(prop.PropertyType)); | ||
| } |
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We don't need to do it in this class. Need to take care of the problematic types globally by making a custom ReflectionConvertors for that type.
2 participants
Problem
Serializing
AssetReferenceSpritecaused infinite recursion:RuntimeType → RuntimeModule → RuntimeAssembly → RuntimeModule → ...
Result: OutOfMemoryException, massive log spam, crash.
Solution
Filter System.Reflection types from
GetSerializableFields()andGetSerializableProperties():Why Correct
Reflection metadata:
Impact
✅ Fixes OutOfMemoryException crashes
✅ Cleaner JSON output without metadata noise
✅ No breaking changes - filters unsupported types only