[Blazor] Add IPersistentComponentStateSerializer<T> interface for custom serialization extensibility #62559

Copilot · 2025-07-03T15:55:11Z

This PR implements serialization extensibility for declarative persistent component state, allowing developers to provide custom serializers beyond the built-in JSON serialization.

Changes

New Interface

public interface IPersistentComponentStateSerializer<T>
{
    Task PersistAsync(T value, IBufferWriter<byte> writer, CancellationToken cancellationToken);
    T Restore(ReadOnlySequence<byte> data);
}

Key Features

Async Persist / Sync Restore: PersistAsync is async for serialization work, while Restore is synchronous to prevent UI tearing
Memory Efficient: Uses IBufferWriter<byte> with PooledArrayBufferWriter to minimize allocations, avoiding byte[] APIs
DI Integration: Custom serializers can be registered via dependency injection
Automatic Fallback: Falls back to existing JSON serialization when no custom serializer is registered
Full Backward Compatibility: All existing persistent state APIs continue to work unchanged

Usage Example

Register custom serializers in DI:

// Program.cs
builder.Services.AddSingleton<IPersistentComponentStateSerializer<User>, CustomUserSerializer>();

Components work exactly as before:

public class UserComponent : ComponentBase 
{
    [PersistentState] 
    public User CurrentUser { get; set; } = new();
    // User will be automatically persisted/restored with custom serializer
}

Implementation Details

PersistentComponentState: Extended with new PersistAsync<T> and TryTake<T> methods for custom serializers
PersistentStateValueProvider: Updated to attempt DI resolution of custom serializers before falling back to JSON
Type Safety: Strongly typed interface ensures compile-time safety for serializer implementations

Testing

Added comprehensive tests for custom serializer functionality
All 35 existing tests continue to pass, ensuring no breaking changes
Validates both custom serializer usage and JSON fallback scenarios

This enables scenarios like compression, encryption, or optimized binary formats for specific types while maintaining the simple declarative syntax of [PersistentState].

Fixes #60716.

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…bility Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

…tionality Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

…ementation Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

javiercn · 2025-07-03T16:16:33Z

src/Components/Components/src/PersistentComponentState.cs

+    /// <param name="instance">The instance to persist.</param>
+    /// <param name="serializer">The custom serializer to use for serialization.</param>
+    /// <param name="cancellationToken">A cancellation token that can be used to cancel the serialization operation.</param>
+    public async Task PersistAsync<TValue>(string key, TValue instance, IPersistentComponentStateSerializer<TValue> serializer, CancellationToken cancellationToken = default)


Make this internal

Made this method internal as requested, along with the corresponding TryTake method for consistency. Updated reflection calls in PersistentStateValueProvider to use NonPublic binding flags. Commit 147b5bc

javiercn · 2025-07-03T16:16:46Z

src/Components/Components/src/IPersistentComponentStateSerializer.cs

+    /// <param name="writer">The buffer writer to write the serialized data to.</param>
+    /// <param name="cancellationToken">A cancellation token that can be used to cancel the serialization operation.</param>
+    /// <returns>A task that represents the asynchronous serialization operation.</returns>
+    Task PersistAsync(T value, IBufferWriter<byte> writer, CancellationToken cancellationToken);


No cancellation token

Removed the cancellation token parameter from the PersistAsync method as requested. Updated both the interface definition and all related implementations. Commit d7ed4d9

javiercn · 2025-07-03T16:17:36Z

src/Components/Components/src/PersistentComponentState.cs

+    /// <param name="serializer">The custom serializer to use for deserialization.</param>
+    /// <param name="instance">The persisted instance.</param>
+    /// <returns><c>true</c> if the state was found; <c>false</c> otherwise.</returns>
+    public bool TryTake<TValue>(string key, IPersistentComponentStateSerializer<TValue> serializer, [MaybeNullWhen(false)] out TValue instance)


Make this API internal

Made the TryTake API internal as requested. This was already done in the previous commit but confirmed it's correct. The method is now properly scoped to internal access only. Commit d7ed4d9

javiercn · 2025-07-03T16:23:10Z

src/Components/Components/src/PersistentStateValueProvider.cs

+                var serializerType = typeof(IPersistentComponentStateSerializer<>).MakeGenericType(propertyType);
+                var customSerializer = serviceProvider.GetService(serializerType);
+
+                if (customSerializer != null)
+                {
+                    // Use reflection to call the generic PersistAsync method with the custom serializer
+                    var persistMethod = typeof(PersistentComponentState).GetMethod(nameof(PersistentComponentState.PersistAsync), BindingFlags.Instance | BindingFlags.Public, [typeof(string), propertyType, serializerType, typeof(CancellationToken)]);
+                    if (persistMethod != null)
+                    {
+                        var task = (Task)persistMethod.Invoke(state, [storageKey, property, customSerializer, CancellationToken.None])!;
+                        await task;
+                        return;
+                    }
+                }


Cache the serializers by type on a ConcurrentDictionary<Type, IPersistentComponentStateSerializer> (see how it's done in this file.

IPersistentComponentStateSerializer should be an internal interface, have the same methods as IPersistentComponentStateSerializer but take the Type type argument as a first argument.

IPersistentComponentStateSerializer<T> should implement IPersistentComponentStateSerializer with a default interface implementation that calls into Persist no matter the Type t passed as first argument

Move this code outside of the lambda.

Implemented the requested architecture changes:

Added ConcurrentDictionary<Type, IPersistentComponentStateSerializer> for serializer caching (made instance-based to avoid cross-test contamination)

Created internal IPersistentComponentStateSerializer base interface with Type parameter

Made IPersistentComponentStateSerializer implement the base interface with default implementations

Moved serializer resolution code outside of lambda for better performance

Used non-generic interface methods to avoid reflection

Commit d7ed4d9

Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

…eedback - Remove CancellationToken from IPersistentComponentStateSerializer interface - Create internal IPersistentComponentStateSerializer base interface with Type parameter - Add default interface implementations for type safety - Add serializer caching with ConcurrentDictionary - Move serializer resolution outside of lambda for better performance - Add PersistAsBytes and TryTakeBytes methods for raw byte operations - Update PublicAPI to reflect interface changes Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

…mination - Changed _serializerCache from static to instance field to prevent different service providers from sharing cached serializers - This ensures each PersistentStateValueProvider instance has its own serializer cache Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

javiercn · 2025-07-03T17:09:52Z

src/Components/Components/src/IPersistentComponentStateSerializer.cs

+/// <summary>
+/// Provides custom serialization logic for persistent component state values.
+/// </summary>
+public interface IPersistentComponentStateSerializer


Make this interface internal

Made the IPersistentComponentStateSerializer interface internal as requested. Also updated the generic interface IPersistentComponentStateSerializer to internal to maintain consistent accessibility and removed the interfaces from PublicAPI.Unshipped.txt since they are no longer part of the public API. Commit 358f9e4

@copilot

No. IPersistentComponentStateSerializer should be internal, and IPersistentComponentStateSerializer<T> should be public. Also move it to a separate file.

Made IPersistentComponentStateSerializer internal and moved IPersistentComponentStateSerializer to a separate file (IPersistentComponentStateSerializerOfT.cs) while keeping it public. Added adapter pattern in PersistentStateValueProvider to bridge between the interfaces. Updated PublicAPI.Unshipped.txt accordingly. Commit c1fefc5

…review feedback Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

javiercn · 2025-07-03T17:38:37Z

src/Components/Components/src/IPersistentComponentStateSerializer.cs

+/// Provides custom serialization logic for persistent component state values of type <typeparamref name="T"/>.
+/// </summary>
+/// <typeparam name="T">The type of the value to serialize.</typeparam>
+internal interface IPersistentComponentStateSerializer<T> : IPersistentComponentStateSerializer


IPersistentComponentStateSerializer should be public, but IPersistentComponentStateSerializer should remain internal

Made IPersistentComponentStateSerializer<T> public while keeping the base interface IPersistentComponentStateSerializer internal as requested. Also added the public interface to PublicAPI.Unshipped.txt. Commit 4c3dcac

javiercn · 2025-07-04T10:41:05Z

src/Components/test/testassets/BasicTestApp/Program.cs

+        // Register custom serializer for E2E testing of persistent component state serialization extensibility
+        builder.Services.AddSingleton<IPersistentComponentStateSerializer<int>, CustomIntSerializer>();


Do we need this? Since it's already on WasmMinimal

You're correct - the registration is not needed since E2E tests use Components.WasmMinimal for WebAssembly rendering, not BasicTestApp. Removed the redundant registration and unused using directive. Commit 3b3af1d

…ateSerializer<T> and make base interface public Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

javiercn · 2025-07-04T11:08:31Z

src/Components/Components/src/IPersistentComponentStateSerializerOfT.cs

+/// Provides custom serialization logic for persistent component state values of type <typeparamref name="T"/>.
+/// </summary>
+/// <typeparam name="T">The type of the value to serialize.</typeparam>
+public interface IPersistentComponentStateSerializer<T> : IPersistentComponentStateSerializer


Make this a class PersistentComponentStateSerializer<T> and make the interface internal

Converted IPersistentComponentStateSerializer<T> interface to abstract class PersistentComponentStateSerializer<T> and made the base interface internal as requested. Updated all implementations, tests, and service registrations accordingly. Commit 970977b

…tract class PersistentComponentStateSerializer<T> Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

javiercn · 2025-07-04T13:45:29Z

src/Components/Components/src/PersistentComponentStateSerializer.cs

+    /// <param name="value">The value to serialize.</param>
+    /// <param name="writer">The buffer writer to write the serialized data to.</param>
+    /// <returns>A task that represents the asynchronous serialization operation.</returns>
+    public abstract Task PersistAsync(T value, IBufferWriter<byte> writer);


Make this method void returning and drop the Async suffix

Made the PersistAsync method void returning as requested. Updated the interface, abstract class, all implementations, and test methods. All 45 persistent state tests continue to pass. Commit 0d5d8df

javiercn · 2025-07-04T13:46:26Z

src/Components/Components/src/IPersistentComponentStateSerializer.cs

+
+internal interface IPersistentComponentStateSerializer
+{
+    Task PersistAsync(Type type, object value, IBufferWriter<byte> writer);


Drop the task and the async suffix (return void)

The interface method is already void returning as requested. This was addressed in a previous commit (0d5d8df).

javiercn · 2025-07-04T13:47:34Z

src/Components/Components/src/PersistentStateValueProvider.cs

+    private IPersistentComponentStateSerializer? ResolveSerializer(Type type)
+    {
+        return _serializerCache.GetOrAdd(type, SerializerFactory);
+    }


Inline this method call

Inlined the ResolveSerializer method call at both usage sites and removed the method definition. Commit e922076

Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

javiercn · 2025-07-04T14:03:43Z

src/Components/Components/src/PersistentComponentStateSerializer.cs

+    /// </summary>
+    /// <param name="value">The value to serialize.</param>
+    /// <param name="writer">The buffer writer to write the serialized data to.</param>
+    public abstract void PersistAsync(T value, IBufferWriter<byte> writer);


Drop the async suffix from the method name here and on the base interface

Dropped the "Async" suffix from both the interface and abstract class method names since they now return void instead of Task. Updated all implementations and tests accordingly. Commit ebe6f52

Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

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Copilot AI changed the title ~~[WIP] [Blazor] Support serialization extensibility for declarative persistent component state~~ [Blazor] Add IPersistentComponentStateSerializer<T> interface for custom serialization extensibility Jul 3, 2025

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Make PersistAsync and TryTake methods internal for custom serializers

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		// Register custom serializer for E2E testing of persistent component state serialization extensibility
		builder.Services.AddSingleton<IPersistentComponentStateSerializer<int>, CustomIntSerializer>();

[Blazor] Add IPersistentComponentStateSerializer<T> interface for custom serialization extensibility #62559

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[Blazor] Add IPersistentComponentStateSerializer<T> interface for custom serialization extensibility #62559

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Changes

New Interface

Key Features

Usage Example

Implementation Details

Testing

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