.Net: Allow custom serialization options to be passed to TextMemoryPl…

…ugin. (microsoft#7098)

### Motivation and Context

When `TextMemoryPlugin` gets back multiple results from the memory store
during recall, it uses json serialization to
turn these multiple results into a single string.
In some cases, this may cause unintended side-affects, e.g. when
non-latin script is present in the results, `JsonSerializer`
automatically escapes these characters.
Adding support for passing custom `JsonSerializerOptions` into the
`TextMemoryPlugin` to customize the serialization behavior.

See microsoft#6593

### Description

Added optional `JsonSerializerOptions` to the `TextMemoryPlugin`
constructor.
Added example to demonstrate this scenario.

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

dotnet/samples/Concepts/Memory/TextMemoryPlugin_RecallJsonSerializationWithOptions.cs

@@ -0,0 +1,80 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Text.Encodings.Web;
+using System.Text.Json;
+using System.Text.Unicode;
+using Microsoft.SemanticKernel;
+using Microsoft.SemanticKernel.Connectors.OpenAI;
+using Microsoft.SemanticKernel.Memory;
+using Microsoft.SemanticKernel.Plugins.Memory;
+
+namespace Memory;
+
+/// <summary>
+/// This example shows how to use custom <see cref="JsonSerializerOptions"/> when serializing multiple results during recall using <see cref="TextMemoryPlugin"/>.
+/// </summary>
+/// <remarks>
+/// When multiple results are returned during recall, <see cref="TextMemoryPlugin"/> has to turn these results into a string to pass back to the kernel.
+/// The <see cref="TextMemoryPlugin"/> uses <see cref="JsonSerializer"/> to turn the results into a string.
+/// In some cases though, the default serialization options may not work, e.g. if the memories contain non-latin text, <see cref="JsonSerializer"/>
+/// will escape these characters by default. In this case, you can provide custom <see cref="JsonSerializerOptions"/> to the <see cref="TextMemoryPlugin"/> to control how the memories are serialized.
+/// </remarks>
+public class TextMemoryPlugin_RecallJsonSerializationWithOptions(ITestOutputHelper output) : BaseTest(output)
+{
+    [Fact]
+    public async Task RunAsync()
+    {
+        // Create a Kernel.
+        var kernelWithoutOptions = Kernel.CreateBuilder()
+            .Build();
+
+        // Create an embedding generator to use for semantic memory.
+        var embeddingGenerator = new AzureOpenAITextEmbeddingGenerationService(TestConfiguration.AzureOpenAIEmbeddings.DeploymentName, TestConfiguration.AzureOpenAIEmbeddings.Endpoint, TestConfiguration.AzureOpenAIEmbeddings.ApiKey);
+
+        // Using an in memory store for this example.
+        var memoryStore = new VolatileMemoryStore();
+
+        // The combination of the text embedding generator and the memory store makes up the 'SemanticTextMemory' object used to
+        // store and retrieve memories.
+        SemanticTextMemory textMemory = new(memoryStore, embeddingGenerator);
+        await textMemory.SaveInformationAsync("samples", "First example of some text in Thai and Bengali: วรรณยุกต์ চলিতভাষা", "test-record-1");
+        await textMemory.SaveInformationAsync("samples", "Second example of some text in Thai and Bengali: วรรณยุกต์ চলিতভাষা", "test-record-2");
+
+        // Import the TextMemoryPlugin into the Kernel without any custom JsonSerializerOptions.
+        var memoryPluginWithoutOptions = kernelWithoutOptions.ImportPluginFromObject(new TextMemoryPlugin(textMemory));
+
+        // Retrieve the memories using the TextMemoryPlugin.
+        var resultWithoutOptions = await kernelWithoutOptions.InvokeAsync(memoryPluginWithoutOptions["Recall"], new()
+        {
+            [TextMemoryPlugin.InputParam] = "Text examples",
+            [TextMemoryPlugin.CollectionParam] = "samples",
+            [TextMemoryPlugin.LimitParam] = "2",
+            [TextMemoryPlugin.RelevanceParam] = "0.79",
+        });
+
+        // The recall operation returned the following text, where the Thai and Bengali text was escaped:
+        // ["Second example of some text in Thai and Bengali: \u0E27\u0E23\u0E23\u0E13\u0E22\u0E38\u0E01\u0E15\u0E4C \u099A\u09B2\u09BF\u09A4\u09AD\u09BE\u09B7\u09BE","First example of some text in Thai and Bengali: \u0E27\u0E23\u0E23\u0E13\u0E22\u0E38\u0E01\u0E15\u0E4C \u099A\u09B2\u09BF\u09A4\u09AD\u09BE\u09B7\u09BE"]
+        Console.WriteLine(resultWithoutOptions.GetValue<string>());
+
+        // Create a Kernel.
+        var kernelWithOptions = Kernel.CreateBuilder()
+            .Build();
+
+        // Import the TextMemoryPlugin into the Kernel with custom JsonSerializerOptions that allow Thai and Bengali script to be serialized unescaped.
+        var options = new JsonSerializerOptions { Encoder = JavaScriptEncoder.Create(UnicodeRanges.BasicLatin, UnicodeRanges.Thai, UnicodeRanges.Bengali) };
+        var memoryPluginWithOptions = kernelWithOptions.ImportPluginFromObject(new TextMemoryPlugin(textMemory, jsonSerializerOptions: options));
+
+        // Retrieve the memories using the TextMemoryPlugin.
+        var result = await kernelWithOptions.InvokeAsync(memoryPluginWithOptions["Recall"], new()
+        {
+            [TextMemoryPlugin.InputParam] = "Text examples",
+            [TextMemoryPlugin.CollectionParam] = "samples",
+            [TextMemoryPlugin.LimitParam] = "2",
+            [TextMemoryPlugin.RelevanceParam] = "0.79",
+        });
+
+        // The recall operation returned the following text, where the Thai and Bengali text was not escaped:
+        // ["Second example of some text in Thai and Bengali: วรรณยุกต์ চলিতভাষা","First example of some text in Thai and Bengali: วรรณยุกต์ চলিতভাষা"]
+        Console.WriteLine(result.GetValue<string>());
+    }
+}

dotnet/samples/Concepts/README.md

@@ -102,6 +102,7 @@ Down below you can find the code snippets that demonstrate the usage of many Sem
 - [TextChunkingAndEmbedding](https://github.com/microsoft/semantic-kernel/blob/main/dotnet/samples/Concepts/Memory/TextChunkingAndEmbedding.cs)
 - [TextMemoryPlugin_GeminiEmbeddingGeneration](https://github.com/microsoft/semantic-kernel/blob/main/dotnet/samples/Concepts/Memory/TextMemoryPlugin_GeminiEmbeddingGeneration.cs)
 - [TextMemoryPlugin_MultipleMemoryStore](https://github.com/microsoft/semantic-kernel/blob/main/dotnet/samples/Concepts/Memory/TextMemoryPlugin_MultipleMemoryStore.cs)
+- [TextMemoryPlugin_RecallJsonSerializationWithOptions](https://github.com/microsoft/semantic-kernel/blob/main/dotnet/samples/Concepts/Memory/TextMemoryPlugin_RecallJsonSerializationWithOptions.cs)
 
 ## Optimization - Examples of different cost and performance optimization techniques
 

dotnet/src/Plugins/Plugins.Memory/TextMemoryPlugin.cs

@@ -49,16 +49,22 @@ public sealed class TextMemoryPlugin
 
     private readonly ISemanticTextMemory _memory;
     private readonly ILogger _logger;
+    private readonly JsonSerializerOptions? _jsonSerializerOptions;
 
     /// <summary>
-    /// Creates a new instance of the TextMemoryPlugin
+    /// Initializes a new instance of the <see cref="TextMemoryPlugin"/> class.
     /// </summary>
+    /// <param name="memory">The <see cref="ISemanticTextMemory"/> instance to use for retrieving and saving memories to and from storage.</param>
+    /// <param name="loggerFactory">The <see cref="ILoggerFactory"/> to use for logging. If null, no logging will be performed.</param>
+    /// <param name="jsonSerializerOptions">An optional <see cref="JsonSerializerOptions"/> to use when turning multiple memories into json text. If null, <see cref="JsonSerializerOptions.Default"/> is used.</param>
     public TextMemoryPlugin(
         ISemanticTextMemory memory,
-        ILoggerFactory? loggerFactory = null)
+        ILoggerFactory? loggerFactory = null,
+        JsonSerializerOptions? jsonSerializerOptions = null)
     {
         this._memory = memory;
         this._logger = loggerFactory?.CreateLogger(typeof(TextMemoryPlugin)) ?? NullLogger.Instance;
+        this._jsonSerializerOptions = jsonSerializerOptions ?? JsonSerializerOptions.Default;
     }
 
     /// <summary>
@@ -128,7 +134,7 @@ public async Task<string> RecallAsync(
             return string.Empty;
         }
 
-        return limit == 1 ? memories[0].Metadata.Text : JsonSerializer.Serialize(memories.Select(x => x.Metadata.Text));
+        return limit == 1 ? memories[0].Metadata.Text : JsonSerializer.Serialize(memories.Select(x => x.Metadata.Text), this._jsonSerializerOptions);
     }
 
     /// <summary>