use enum

Author: LittleLittleCloud

app/backend/Extensions/SearchClientExtensions.cs

@@ -41,7 +41,7 @@ internal static async Task<SupportingContentRecord[]> QueryDocumentsAsync(
                 Size = top,
             };
 
-        if (embedding != null && overrides?.RetrievalMode != "Text")
+        if (embedding != null && overrides?.RetrievalMode != RetrievalMode.Text)
         {
             var k = useSemanticRanker ? 50 : top;
             var vectorQuery = new VectorizedQuery(embedding)

app/backend/Services/ReadRetrieveReadChatService.cs

@@ -45,15 +45,15 @@ public async Task<ApproachResponse> ReplyAsync(
         var question = history.LastOrDefault()?.User is { } userQuestion
             ? userQuestion
             : throw new InvalidOperationException("Use question is null");
-        if (overrides?.RetrievalMode != "Text" && embedding is not null)
+        if (overrides?.RetrievalMode != RetrievalMode.Text && embedding is not null)
         {
             embeddings = (await embedding.GenerateEmbeddingAsync(question, cancellationToken: cancellationToken)).ToArray();
         }
 
         // step 1
         // use llm to get query if retrieval mode is not vector
         string? query = null;
-        if (overrides?.RetrievalMode != "Vector")
+        if (overrides?.RetrievalMode != RetrievalMode.Vector)
         {
             var getQueryChat = chat.CreateNewChat(@"You are a helpful AI assistant, generate search query for followup question.
 Make your respond simple and precise. Return the query only, do not return any other text.

app/shared/Shared/Models/RequestOverrides.cs

@@ -2,11 +2,17 @@
 
 namespace Shared.Models;
 
+public enum RetrievalMode
+{
+    Text = 0,
+    Vector,
+    Hybrid,
+}
 public record RequestOverrides
 {
     public bool SemanticRanker { get; set; } = false;
 
-    public string RetrievalMode { get; set; } = "Vector"; // available option: Text, Vector, Hybrid
+    public RetrievalMode RetrievalMode { get; set; } = RetrievalMode.Vector; // available option: Text, Vector, Hybrid
 
     public bool? SemanticCaptions { get; set; }
     public string? ExcludeCategory { get; set; }

app/shared/Shared/Services/AzureDocumentService.cs

@@ -55,7 +55,7 @@ public async Task<SupportingContentRecord[]> QueryDocumentsAsync(
                 Size = top,
             };
 
-        if (embedding != null && overrides?.RetrievalMode != "Text")
+        if (embedding != null && overrides?.RetrievalMode != RetrievalMode.Text)
         {
             var k = useSemanticRanker ? 50 : top;
             var vectorQuery = new VectorizedQuery(embedding)

app/tests/MinimalApi.Tests/AzureDocumentSearchServiceTest.cs

@@ -26,7 +26,7 @@ public async Task QueryDocumentsTestTextOnlyAsync()
         // query only
         var option = new RequestOverrides
         {
-            RetrievalMode = "Text",
+            RetrievalMode = RetrievalMode.Text,
             Top = 3,
             SemanticCaptions = true,
             SemanticRanker = true,
@@ -54,7 +54,7 @@ public async Task QueryDocumentsTestEmbeddingOnlyAsync()
         // query only
         var option = new RequestOverrides
         {
-            RetrievalMode = "Vector",
+            RetrievalMode = RetrievalMode.Vector,
             Top = 3,
             SemanticCaptions = true,
             SemanticRanker = true,

app/tests/MinimalApi.Tests/ReadRetrieveReadChatServiceTest.cs

@@ -49,7 +49,7 @@ public async Task NorthwindHealthQuestionTest_TextOnlyAsync()
         };
         var overrides = new RequestOverrides
         {
-            RetrievalMode = "Text",
+            RetrievalMode = RetrievalMode.Text,
             Top = 2,
             SemanticCaptions = true,
             SemanticRanker = true,