Sanitize structured output schema type name to satisfy restrictions (#5504)

Author: eiriktsarpalis

src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/FunctionCallHelpers.cs

@@ -14,6 +14,7 @@
 using System.Text.Json.Nodes;
 using System.Text.Json.Schema;
 using System.Text.Json.Serialization;
+using System.Text.RegularExpressions;
 using Microsoft.Shared.Diagnostics;
 
 using FunctionParameterKey = (System.Type? Type, string ParameterName, string? Description, bool HasDefaultValue, object? DefaultValue);
@@ -375,4 +376,20 @@ private static JsonElement ParseJsonElement(ReadOnlySpan<byte> utf8Json)
     [JsonSerializable(typeof(JsonElement))]
     [JsonSerializable(typeof(JsonDocument))]
     private sealed partial class FunctionCallHelperContext : JsonSerializerContext;
+
+    /// <summary>
+    /// Remove characters from method name that are valid in metadata but shouldn't be used in a method name.
+    /// This is primarily intended to remove characters emitted by for compiler-generated method name mangling.
+    /// </summary>
+    public static string SanitizeMetadataName(string metadataName) =>
+        InvalidNameCharsRegex().Replace(metadataName, "_");
+
+    /// <summary>Regex that flags any character other than ASCII digits or letters or the underscore.</summary>
+#if NET
+    [GeneratedRegex("[^0-9A-Za-z_]")]
+    private static partial Regex InvalidNameCharsRegex();
+#else
+    private static Regex InvalidNameCharsRegex() => _invalidNameCharsRegex;
+    private static readonly Regex _invalidNameCharsRegex = new("[^0-9A-Za-z_]", RegexOptions.Compiled);
+#endif
 }

src/Libraries/Microsoft.Extensions.AI/ChatCompletion/ChatClientStructuredOutputExtensions.cs

@@ -14,6 +14,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Shared.Diagnostics;
+using static Microsoft.Extensions.AI.FunctionCallHelpers;
 
 namespace Microsoft.Extensions.AI;
 
@@ -167,7 +168,7 @@ public static async Task<ChatCompletion<T>> CompleteAsync<T>(
             // the LLM backend is meant to do whatever's needed to explain the schema to the LLM.
             options.ResponseFormat = ChatResponseFormat.ForJsonSchema(
                 schema,
-                schemaName: typeof(T).Name,
+                schemaName: SanitizeMetadataName(typeof(T).Name),
                 schemaDescription: typeof(T).GetCustomAttribute<DescriptionAttribute>()?.Description);
         }
         else

src/Libraries/Microsoft.Extensions.AI/Functions/AIFunctionFactory.cs

@@ -12,20 +12,16 @@
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using System.Text.Json.Serialization.Metadata;
-using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Shared.Collections;
 using Microsoft.Shared.Diagnostics;
+using static Microsoft.Extensions.AI.FunctionCallHelpers;
 
 namespace Microsoft.Extensions.AI;
 
 /// <summary>Provides factory methods for creating commonly-used implementations of <see cref="AIFunction"/>.</summary>
-public static
-#if NET
-    partial
-#endif
-    class AIFunctionFactory
+public static class AIFunctionFactory
 {
     internal const string UsesReflectionJsonSerializerMessage =
         "This method uses the reflection-based JsonSerializer which can break in trimmed or AOT applications.";
@@ -107,11 +103,7 @@ public static AIFunction Create(MethodInfo method, object? target, AIFunctionFac
         return new ReflectionAIFunction(method, target, options);
     }
 
-    private sealed
-#if NET
-        partial
-#endif
-        class ReflectionAIFunction : AIFunction
+    private sealed class ReflectionAIFunction : AIFunction
     {
         private readonly MethodInfo _method;
         private readonly object? _target;
@@ -474,21 +466,5 @@ private static MethodInfo GetMethodFromGenericMethodDefinition(Type specializedT
 #pragma warning restore S3011 // Reflection should not be used to increase accessibility of classes, methods, or fields
             return specializedType.GetMethods(All).First(m => m.MetadataToken == genericMethodDefinition.MetadataToken);
         }
-
-        /// <summary>
-        /// Remove characters from method name that are valid in metadata but shouldn't be used in a method name.
-        /// This is primarily intended to remove characters emitted by for compiler-generated method name mangling.
-        /// </summary>
-        private static string SanitizeMetadataName(string methodName) =>
-            InvalidNameCharsRegex().Replace(methodName, "_");
-
-        /// <summary>Regex that flags any character other than ASCII digits or letters or the underscore.</summary>
-#if NET
-        [GeneratedRegex("[^0-9A-Za-z_]")]
-        private static partial Regex InvalidNameCharsRegex();
-#else
-        private static Regex InvalidNameCharsRegex() => _invalidNameCharsRegex;
-        private static readonly Regex _invalidNameCharsRegex = new("[^0-9A-Za-z_]", RegexOptions.Compiled);
-#endif
     }
 }

test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/ChatClientStructuredOutputExtensionsTests.cs

@@ -172,6 +172,40 @@ public async Task CanUseNativeStructuredOutput()
         Assert.Equal("Hello", Assert.Single(chatHistory).Text);
     }
 
+    [Fact]
+    public async Task CanUseNativeStructuredOutputWithSanitizedTypeName()
+    {
+        var expectedResult = new Data<Animal> { Value = new Animal { Id = 1, FullName = "Tigger", Species = Species.Tiger } };
+        var expectedCompletion = new ChatCompletion([new ChatMessage(ChatRole.Assistant, JsonSerializer.Serialize(expectedResult))]);
+
+        using var client = new TestChatClient
+        {
+            CompleteAsyncCallback = (messages, options, cancellationToken) =>
+            {
+                var responseFormat = Assert.IsType<ChatResponseFormatJson>(options!.ResponseFormat);
+
+                Assert.Matches("Data_1", responseFormat.SchemaName);
+
+                return Task.FromResult(expectedCompletion);
+            },
+        };
+
+        var chatHistory = new List<ChatMessage> { new(ChatRole.User, "Hello") };
+        var response = await client.CompleteAsync<Data<Animal>>(chatHistory, useNativeJsonSchema: true);
+
+        // The completion contains the deserialized result and other completion properties
+        Assert.Equal(1, response.Result!.Value!.Id);
+        Assert.Equal("Tigger", response.Result.Value.FullName);
+        Assert.Equal(Species.Tiger, response.Result.Value.Species);
+
+        // TryGetResult returns the same value
+        Assert.True(response.TryGetResult(out var tryGetResultOutput));
+        Assert.Same(response.Result, tryGetResultOutput);
+
+        // History remains unmutated
+        Assert.Equal("Hello", Assert.Single(chatHistory).Text);
+    }
+
     [Fact]
     public async Task CanSpecifyCustomJsonSerializationOptions()
     {
@@ -247,6 +281,11 @@ private class Animal
         public Species Species { get; set; }
     }
 
+    private class Data<T>
+    {
+        public T? Value { get; set; }
+    }
+
     private enum Species
     {
         Bear,