[Blazor] SupplyParameterFromForm dictionary support (#48565)

* Adds support for binding dictionaries of primitive types.

Author: javiercn

src/Components/Endpoints/src/Binding/Converters/DictionaryAdapters/DictionaryBufferAdapter.cs

@@ -0,0 +1,21 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
+
+// Uses a concrete type that implements IDictionary<TKey, TValue> as a buffer.
+internal sealed class DictionaryBufferAdapter<TDictionaryType, TKey, TValue>
+    : IDictionaryBufferAdapter<TDictionaryType, TDictionaryType, TKey, TValue>
+    where TDictionaryType : IDictionary<TKey, TValue>, new()
+    where TKey : IParsable<TKey>
+{
+    public static TDictionaryType Add(ref TDictionaryType buffer, TKey key, TValue value)
+    {
+        buffer.Add(key, value);
+        return buffer;
+    }
+
+    public static TDictionaryType CreateBuffer() => new TDictionaryType();
+
+    public static TDictionaryType ToResult(TDictionaryType buffer) => buffer;
+}

src/Components/Endpoints/src/Binding/Converters/DictionaryAdapters/DictionaryStaticCastAdapter.cs

@@ -0,0 +1,18 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
+
+// Adapts a concrete dictionary type into an interface.
+internal sealed class DictionaryStaticCastAdapter<TDictionaryInterface, TDictionaryImplementation, TDictionaryAdapter, TBuffer, TKey, TValue>
+    : IDictionaryBufferAdapter<TDictionaryInterface, TBuffer, TKey, TValue>
+    where TDictionaryAdapter : IDictionaryBufferAdapter<TDictionaryImplementation, TBuffer, TKey, TValue>
+    where TDictionaryImplementation : TDictionaryInterface
+    where TKey : IParsable<TKey>
+{
+    public static TBuffer CreateBuffer() => TDictionaryAdapter.CreateBuffer();
+
+    public static TBuffer Add(ref TBuffer buffer, TKey key, TValue element) => TDictionaryAdapter.Add(ref buffer, key, element);
+
+    public static TDictionaryInterface ToResult(TBuffer buffer) => TDictionaryAdapter.ToResult(buffer);
+}

src/Components/Endpoints/src/Binding/Converters/DictionaryAdapters/IDictionaryBufferAdapter.cs

@@ -0,0 +1,19 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
+
+// Interface for constructing a dictionary like instance using the
+// dictionary converter.
+// This interface abstracts over the different ways of constructing a dictionary.
+// For example, Immutable types use a builder as a buffer, while other types
+// use an instance of the dictionary itself as a buffer.
+internal interface IDictionaryBufferAdapter<TDictionary, TBuffer, TKey, TValue>
+    where TKey : IParsable<TKey>
+{
+    public static abstract TBuffer CreateBuffer();
+
+    public static abstract TBuffer Add(ref TBuffer buffer, TKey key, TValue value);
+
+    public static abstract TDictionary ToResult(TBuffer buffer);
+}

src/Components/Endpoints/src/Binding/Converters/DictionaryAdapters/ImmutableDictionaryBufferAdapter.cs

@@ -0,0 +1,36 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Immutable;
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
+
+internal sealed class ImmutableDictionaryBufferAdapter<TKey, TValue>
+    : IDictionaryBufferAdapter<ImmutableDictionary<TKey, TValue>, ImmutableDictionary<TKey, TValue>.Builder, TKey, TValue>
+    where TKey : IParsable<TKey>
+{
+    public static ImmutableDictionary<TKey, TValue>.Builder Add(ref ImmutableDictionary<TKey, TValue>.Builder buffer, TKey key, TValue value)
+    {
+        buffer.Add(key, value);
+        return buffer;
+    }
+
+    public static ImmutableDictionary<TKey, TValue>.Builder CreateBuffer() => ImmutableDictionary.CreateBuilder<TKey, TValue>();
+
+    public static ImmutableDictionary<TKey, TValue> ToResult(ImmutableDictionary<TKey, TValue>.Builder buffer) => buffer.ToImmutable();
+
+    internal static DictionaryConverter<IImmutableDictionary<TKey, TValue>> CreateInterfaceConverter(FormDataConverter<TValue> valueTypeConverter)
+    {
+        return new DictionaryConverter<IImmutableDictionary<TKey, TValue>,
+            DictionaryStaticCastAdapter<
+                IImmutableDictionary<TKey, TValue>,
+                ImmutableDictionary<TKey, TValue>,
+                ImmutableDictionaryBufferAdapter<TKey, TValue>,
+                ImmutableDictionary<TKey, TValue>.Builder,
+                TKey,
+                TValue>,
+            ImmutableDictionary<TKey, TValue>.Builder,
+            TKey,
+            TValue>(valueTypeConverter);
+    }
+}

src/Components/Endpoints/src/Binding/Converters/DictionaryAdapters/ImmutableSortedDictionaryBufferAdapter.cs

@@ -0,0 +1,21 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Immutable;
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
+
+internal sealed class ImmutableSortedDictionaryBufferAdapter<TKey, TValue>
+    : IDictionaryBufferAdapter<ImmutableSortedDictionary<TKey, TValue>, ImmutableSortedDictionary<TKey, TValue>.Builder, TKey, TValue>
+    where TKey : IParsable<TKey>
+{
+    public static ImmutableSortedDictionary<TKey, TValue>.Builder Add(ref ImmutableSortedDictionary<TKey, TValue>.Builder buffer, TKey key, TValue value)
+    {
+        buffer.Add(key, value);
+        return buffer;
+    }
+
+    public static ImmutableSortedDictionary<TKey, TValue>.Builder CreateBuffer() => ImmutableSortedDictionary.CreateBuilder<TKey, TValue>();
+
+    public static ImmutableSortedDictionary<TKey, TValue> ToResult(ImmutableSortedDictionary<TKey, TValue>.Builder buffer) => buffer.ToImmutable();
+}

src/Components/Endpoints/src/Binding/Converters/DictionaryAdapters/ReadOnlyDictionaryBufferAdapter.cs

@@ -0,0 +1,47 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.ObjectModel;
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
+
+internal sealed class ReadOnlyDictionaryBufferAdapter<TKey, TValue>
+    : IDictionaryBufferAdapter<ReadOnlyDictionary<TKey, TValue>, Dictionary<TKey, TValue>, TKey, TValue>
+    where TKey : IParsable<TKey>
+{
+    public static Dictionary<TKey, TValue> Add(ref Dictionary<TKey, TValue> buffer, TKey key, TValue value)
+    {
+        buffer.Add(key, value);
+        return buffer;
+    }
+
+    public static Dictionary<TKey, TValue> CreateBuffer() =>
+        new Dictionary<TKey, TValue>();
+
+    public static ReadOnlyDictionary<TKey, TValue> ToResult(Dictionary<TKey, TValue> buffer) =>
+        new ReadOnlyDictionary<TKey, TValue>(buffer);
+
+    internal static DictionaryConverter<IReadOnlyDictionary<TKey, TValue>> CreateInterfaceConverter(FormDataConverter<TValue> valueTypeConverter)
+    {
+        return new DictionaryConverter<IReadOnlyDictionary<TKey, TValue>,
+            DictionaryStaticCastAdapter<
+                IReadOnlyDictionary<TKey, TValue>,
+                ReadOnlyDictionary<TKey, TValue>,
+                ReadOnlyDictionaryBufferAdapter<TKey, TValue>,
+                Dictionary<TKey, TValue>,
+                TKey,
+                TValue>,
+            Dictionary<TKey, TValue>,
+            TKey,
+            TValue>(valueTypeConverter);
+    }
+
+    internal static DictionaryConverter<ReadOnlyDictionary<TKey, TValue>> CreateConverter(FormDataConverter<TValue> valueTypeConverter)
+    {
+        return new DictionaryConverter<ReadOnlyDictionary<TKey, TValue>,
+            ReadOnlyDictionaryBufferAdapter<TKey, TValue>,
+            Dictionary<TKey, TValue>,
+            TKey,
+            TValue>(valueTypeConverter);
+    }
+}

src/Components/Endpoints/src/Binding/Converters/DictionaryConverter.cs

@@ -0,0 +1,81 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
+
+internal abstract class DictionaryConverter<TDictionary> : FormDataConverter<TDictionary>
+{
+}
+
+internal sealed class DictionaryConverter<TDictionary, TDictionaryPolicy, TBuffer, TKey, TValue> : DictionaryConverter<TDictionary>
+    where TKey : IParsable<TKey>
+    where TDictionaryPolicy : IDictionaryBufferAdapter<TDictionary, TBuffer, TKey, TValue>
+{
+    private readonly FormDataConverter<TValue> _valueConverter;
+
+    public DictionaryConverter(FormDataConverter<TValue> elementConverter)
+    {
+        ArgumentNullException.ThrowIfNull(elementConverter);
+
+        _valueConverter = elementConverter;
+    }
+
+    internal override bool TryRead(
+        ref FormDataReader context,
+        Type type,
+        FormDataMapperOptions options,
+        [NotNullWhen(true)] out TDictionary? result,
+        out bool found)
+    {
+        TValue currentValue;
+        TBuffer buffer;
+        bool foundCurrentValue;
+        bool currentElementSuccess;
+        bool succeded = true;
+
+        found = context.GetKeys().GetEnumerator().MoveNext();
+        if (!found)
+        {
+            result = default!;
+            return true;
+        }
+
+        buffer = TDictionaryPolicy.CreateBuffer();
+
+        // We can't precompute dictionary anyKeys ahead of time,
+        // so the moment we find a dictionary, we request the list of anyKeys
+        // for the current location, which will involve parsing the form data anyKeys
+        // and building a tree of anyKeys.
+        var keyCount = 0;
+        var maxCollectionSize = options.MaxCollectionSize;
+
+        foreach (var key in context.GetKeys())
+        {
+            context.PushPrefix(key);
+            currentElementSuccess = _valueConverter.TryRead(ref context, typeof(TValue), options, out currentValue!, out foundCurrentValue);
+            context.PopPrefix(key);
+
+            if (!TKey.TryParse(key[1..^1], CultureInfo.InvariantCulture, out var keyValue))
+            {
+                succeded = false;
+                // Will report an error about unparsable key here.
+
+                // Continue trying to bind the rest of the dictionary.
+                continue;
+            }
+
+            TDictionaryPolicy.Add(ref buffer, keyValue!, currentValue);
+            keyCount++;
+            if (keyCount == maxCollectionSize)
+            {
+                succeded = false;
+                break;
+            }
+        }
+
+        result = TDictionaryPolicy.ToResult(buffer);
+        return succeded;
+    }
+}

src/Components/Endpoints/src/Binding/Factories/CollectionConverterFactory.cs

@@ -12,14 +12,20 @@ internal class CollectionConverterFactory : IFormDataConverterFactory
     public bool CanConvert(Type type, FormDataMapperOptions options)
     {
         var enumerable = ClosedGenericMatcher.ExtractGenericInterface(type, typeof(IEnumerable<>));
-        if (enumerable == null && !type.IsArray && type.GetArrayRank() != 1)
+        if (enumerable == null && !(type.IsArray && type.GetArrayRank() == 1))
         {
             return false;
         }
 
         var element = enumerable != null ? enumerable.GetGenericArguments()[0] : type.GetElementType()!;
 
-        return options.HasConverter(element);
+        if (Activator.CreateInstance(typeof(TypedCollectionConverterFactory<,>)
+            .MakeGenericType(type, element!)) is not IFormDataConverterFactory factory)
+        {
+            return false;
+        }
+
+        return factory.CanConvert(type, options);
     }
 
     public FormDataConverter CreateConverter(Type type, FormDataMapperOptions options)

src/Components/Endpoints/src/Binding/Factories/Collections/CollectionLikeTypedCollectionConverterFactory.cs renamed to src/Components/Endpoints/src/Binding/Factories/Collections/ConcreteTypeCollectionConverterFactory.cs

@@ -3,10 +3,10 @@
 
 namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
 
-internal sealed class CollectionLikeTypedCollectionConverterFactory<TCollection, TElement>
+internal class ConcreteTypeCollectionConverterFactory<TCollection, TElement>
     : IFormDataConverterFactory
 {
-    public static readonly CollectionLikeTypedCollectionConverterFactory<TCollection, TElement> Instance =
+    public static readonly ConcreteTypeCollectionConverterFactory<TCollection, TElement> Instance =
         new();
 
     public bool CanConvert(Type _, FormDataMapperOptions options) => true;

src/Components/Endpoints/src/Binding/Factories/Collections/TypedCollectionConverterFactory.cs

@@ -155,7 +155,7 @@ var _ when type.IsAssignableTo(typeof(ImmutableStack<TElement>)) =>
                 // Some of the types above implement ICollection<T>, but do so in a very inneficient way, so we want to
                 // use special converters for them.
                 var _ when type.IsAssignableTo(typeof(ICollection<TElement>))
-                    => CollectionLikeTypedCollectionConverterFactory<TCollection, TElement>.Instance.CreateConverter(typeof(TCollection), options),
+                    => ConcreteTypeCollectionConverterFactory<TCollection, TElement>.Instance.CreateConverter(typeof(TCollection), options),
                 _ => throw new InvalidOperationException($"Unable to create converter for '{typeof(TCollection).FullName}'.")
             };
         }

src/Components/Endpoints/src/Binding/Factories/Dictionary/ConcreteTypeDictionaryConverterFactory.cs

@@ -0,0 +1,51 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Binding;
+
+internal sealed class ConcreteTypeDictionaryConverterFactory<TDictionary, TKey, TValue> : IFormDataConverterFactory
+    where TKey : IParsable<TKey>
+{
+    public static readonly ConcreteTypeDictionaryConverterFactory<TDictionary, TKey, TValue> Instance = new();
+
+    public bool CanConvert(Type type, FormDataMapperOptions options) => true;
+
+    public FormDataConverter CreateConverter(Type type, FormDataMapperOptions options)
+    {
+        // Resolve the element type converter
+        var keyConverter = options.ResolveConverter<TKey>() ??
+            throw new InvalidOperationException($"Unable to create converter for '{typeof(TDictionary).FullName}'.");
+
+        var valueConverter = options.ResolveConverter<TValue>() ??
+            throw new InvalidOperationException($"Unable to create converter for '{typeof(TDictionary).FullName}'.");
+
+        var customFactory = Activator.CreateInstance(typeof(CustomDictionaryConverterFactory<>)
+            .MakeGenericType(typeof(TDictionary), typeof(TKey), typeof(TValue), typeof(TDictionary))) as CustomDictionaryConverterFactory;
+
+        if (customFactory == null)
+        {
+            throw new InvalidOperationException($"Unable to create converter for type '{typeof(TDictionary).FullName}'.");
+        }
+
+        return customFactory.CreateConverter(keyConverter, valueConverter);
+    }
+
+    private abstract class CustomDictionaryConverterFactory
+    {
+        public abstract FormDataConverter CreateConverter(FormDataConverter<TKey> keyConverter, FormDataConverter<TValue> valueConverter);
+    }
+
+    private class CustomDictionaryConverterFactory<TCustomDictionary> : CustomDictionaryConverterFactory
+        where TCustomDictionary : TDictionary, IDictionary<TKey, TValue>, new()
+    {
+        public override FormDataConverter CreateConverter(FormDataConverter<TKey> keyConverter, FormDataConverter<TValue> valueConverter)
+        {
+            return new DictionaryConverter<
+                TCustomDictionary,
+                DictionaryBufferAdapter<TCustomDictionary, TKey, TValue>,
+                TCustomDictionary,
+                TKey,
+                TValue>(valueConverter);
+        }
+    }
+}