Enhance stored prompt handling by adding variable support and improving JSON serialization

Author: YairSadan

examples/Responses/Example03_StoredPrompts.cs

@@ -1,6 +1,7 @@
 using NUnit.Framework;
 using OpenAI.Responses;
 using System;
+using System.Collections.Generic;
 
 namespace OpenAI.Examples;
 
@@ -25,7 +26,9 @@ public void Example03_StoredPrompts()
         options.Prompt.Variables["location"] = "San Francisco";
         options.Prompt.Variables["unit"] = "celsius";
 
-        OpenAIResponse response = client.CreateResponse([], options);
+        // Use stored prompt with variables
+        IEnumerable<ResponseItem> inputItems = Array.Empty<ResponseItem>();
+        OpenAIResponse response = client.CreateResponse(inputItems, options);
 
         Console.WriteLine($"[ASSISTANT]: {response.GetOutputText()}");
     }

examples/Responses/Example03_StoredPromptsAsync.cs

@@ -1,6 +1,7 @@
 using NUnit.Framework;
 using OpenAI.Responses;
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 
 namespace OpenAI.Examples;
@@ -26,7 +27,9 @@ public async Task Example03_StoredPromptsAsync()
         options.Prompt.Variables["location"] = "San Francisco";
         options.Prompt.Variables["unit"] = "celsius";
 
-        OpenAIResponse response = await client.CreateResponseAsync([], options);
+        // Use stored prompt with variables
+        IEnumerable<ResponseItem> inputItems = Array.Empty<ResponseItem>();
+        OpenAIResponse response = await client.CreateResponseAsync(inputItems, options);
 
         Console.WriteLine($"[ASSISTANT]: {response.GetOutputText()}");
     }

src/Custom/Responses/ResponsePrompt.Serialization.cs

@@ -44,7 +44,51 @@ internal static void SerializeResponsePrompt(ResponsePrompt instance, Utf8JsonWr
             foreach (var variable in instance.Variables)
             {
                 writer.WritePropertyName(variable.Key);
-                JsonSerializer.Serialize(writer, variable.Value, options.Format == "W" ? null : (JsonSerializerOptions)null);
+                if (variable.Value is JsonElement element)
+                {
+#if NET6_0_OR_GREATER
+                    writer.WriteRawValue(element.GetRawText());
+#else
+                    using JsonDocument document = JsonDocument.Parse(element.GetRawText());
+                    JsonSerializer.Serialize(writer, document.RootElement);
+#endif
+                }
+                else if (variable.Value != null)
+                {
+                    // Handle primitive types directly
+                    switch (variable.Value)
+                    {
+                        case string str:
+                            writer.WriteStringValue(str);
+                            break;
+                        case int intVal:
+                            writer.WriteNumberValue(intVal);
+                            break;
+                        case long longVal:
+                            writer.WriteNumberValue(longVal);
+                            break;
+                        case float floatVal:
+                            writer.WriteNumberValue(floatVal);
+                            break;
+                        case double doubleVal:
+                            writer.WriteNumberValue(doubleVal);
+                            break;
+                        case decimal decimalVal:
+                            writer.WriteNumberValue(decimalVal);
+                            break;
+                        case bool boolVal:
+                            writer.WriteBooleanValue(boolVal);
+                            break;
+                        default:
+                            // For other types, write as string value
+                            writer.WriteStringValue(variable.Value.ToString());
+                            break;
+                    }
+                }
+                else
+                {
+                    writer.WriteNullValue();
+                }
             }
             writer.WriteEndObject();
         }
@@ -77,7 +121,17 @@ internal static ResponsePrompt DeserializeResponsePrompt(JsonElement element, Mo
             {
                 foreach (var variable in property.Value.EnumerateObject())
                 {
-                    variables[variable.Name] = JsonSerializer.Deserialize<object>(variable.Value.GetRawText());
+                    // Handle different JSON value types appropriately
+                    object value = variable.Value.ValueKind switch
+                    {
+                        JsonValueKind.String => variable.Value.GetString(),
+                        JsonValueKind.Number => variable.Value.TryGetInt32(out int intVal) ? intVal : variable.Value.GetDouble(),
+                        JsonValueKind.True => true,
+                        JsonValueKind.False => false,
+                        JsonValueKind.Null => null,
+                        _ => variable.Value.GetRawText() // For objects/arrays, store as raw JSON string
+                    };
+                    variables[variable.Name] = value;
                 }
             }
         }
@@ -86,6 +140,7 @@ internal static ResponsePrompt DeserializeResponsePrompt(JsonElement element, Mo
         result.Id = id;
         result.Version = version;
 
+        // Add variables to the existing dictionary (Variables property is get-only)
         if (variables.Count > 0)
         {
             foreach (var variable in variables)