Several improvements / fixes for functions

OpenAI.Playground/TestHelpers/ChatCompletionTestHelper.cs

@@ -112,6 +112,13 @@ public static async Task RunChatFunctionCallTest(IOpenAIService sdk)
                 @enum: new List<string> { "celsius", "fahrenheit" })
             .AddParameter("num_days", "integer", "The number of days to forecast")
             .Build();
+
+        var fn3 = new FunctionDefinitionBuilder("get_current_datetime", "Get the current date and time, e.g. 'Saturday, June 24, 2023 6:14:14 PM'")
+            .Build();
+
+        var fn4 = new FunctionDefinitionBuilder("identify_number_sequence", "Get a sequence of numbers present in the user message")
+            .AddArrayParameter("values", "number", "Sequence of numbers specified by the user")
+            .Build();
 
         try
         {
@@ -121,16 +128,21 @@ public static async Task RunChatFunctionCallTest(IOpenAIService sdk)
                 Messages = new List<ChatMessage>
                 {
                     ChatMessage.FromSystem("Don't make assumptions about what values to plug into functions. Ask for clarification if a user request is ambiguous."),
+
+                    // to test weather forecast functions:
                     ChatMessage.FromUser("Give me a weather report for Chicago, USA, for the next 5 days."),
+
+                    // or to test array functions, use this instead:
+                    // ChatMessage.FromUser("The combination is: One. Two. Three. Four. Five."),
                 },
-                Functions = new List<FunctionDefinition> { fn1, fn2 },
+                Functions = new List<FunctionDefinition> { fn1, fn2, fn3, fn4 },
                 // optionally, to force a specific function:
                 // FunctionCall = new Dictionary<string, string> { { "name", "get_current_weather" } },
                 MaxTokens = 50,
                 Model = Models.Gpt_3_5_Turbo_0613
             });
 
-            /*  expected output along the lines of:
+            /*  when testing weather forecasts, expected output should be along the lines of:
 
                 Message:
                 Function call:  get_n_day_weather_forecast
@@ -139,6 +151,13 @@ public static async Task RunChatFunctionCallTest(IOpenAIService sdk)
                   num_days: 5
             */
 
+            /*  when testing array functions, expected output should be along the lines of:
+
+                Message:
+                Function call:  identify_number_sequence
+                  values: [1, 2, 3, 4, 5]
+            */ 
+
             await foreach (var completionResult in completionResults)
             {
                 if (completionResult.Successful)

OpenAI.SDK/ObjectModels/RequestModels/ChatMessage.cs

@@ -163,6 +163,14 @@ public class FunctionParameterPropertyValue
     [JsonPropertyName("type")]
     public string Type { get; set; } = "string";
 
+    /// <summary>
+    ///     If type is "array", this specifies the element type for all items in the array.
+    ///     If type is not "array", this should be null.
+    ///     For more details, see https://json-schema.org/understanding-json-schema/reference/array.html
+    /// </summary>
+    [JsonPropertyName("items")]
+    public ArrayItemsDefinition? Items { get; set; }
+
     /// <summary>
     ///     Optional. Argument description.
     /// </summary>
@@ -174,6 +182,22 @@ public class FunctionParameterPropertyValue
     /// </summary>
     [JsonPropertyName("enum")]
     public IList<string>? Enum { get; set; }
+
+    public class ArrayItemsDefinition
+    {
+        /// <summary> 
+        ///     Argument type for all array items (e.g. string, integer, and so on). 
+        ///     For examples, see https://json-schema.org/understanding-json-schema/reference/object.html
+        /// </summary>
+        [JsonPropertyName("type")]
+        public string Type { get; set; } = "string";
+
+        /// <summary>
+        ///     Optional. Array item description.
+        /// </summary>
+        [JsonPropertyName("description")]
+        public string? Description { get; set; }
+    }
 }
 
 public class FunctionDefinitionBuilder
@@ -187,7 +211,11 @@ public FunctionDefinitionBuilder(string fnName, string? fnDescription)
         _definition = new()
         {
             Name = fnName,
-            Description = fnDescription
+            Description = fnDescription,
+            Parameters = new FunctionParameters
+            {
+                Properties = new Dictionary<string, FunctionParameterPropertyValue>()
+            }
         };
     }
 
@@ -222,19 +250,35 @@ public FunctionDefinitionBuilder AddParameter(
         string name, string type, string? description = null,
         IList<string>? @enum = null, bool required = true)
     {
-        _definition.Parameters ??= new FunctionParameters();
-        _definition.Parameters.Properties ??= new Dictionary<string, FunctionParameterPropertyValue>();
+        var value = new FunctionParameterPropertyValue() { Type = type, Description = description, Enum = @enum };
+
+        Add(name, value, required);
 
-        _definition.Parameters.Properties[name] =
-            new FunctionParameterPropertyValue() { Type = type, Description = description, Enum = @enum };
+        return this;
+    }
 
+    public FunctionDefinitionBuilder AddArrayParameter(
+        string name, string itemType, string? description = null, string? itemDescription = null,
+        IList<string>? @enum = null, bool required = true)
+    {
+        var items = new FunctionParameterPropertyValue.ArrayItemsDefinition { Type = itemType, Description = itemDescription };
+        var value = new FunctionParameterPropertyValue() { Type = "array", Items = items, Description = description, Enum = @enum };
+
+        Add(name, value, required);
+
+        return this;
+    }
+
+    private void Add(string name, FunctionParameterPropertyValue value, bool required)
+    {
+        var pars = _definition.Parameters!;
+        pars.Properties![name] = value;
+
         if (required)
         {
-            _definition.Parameters.Required ??= new List<string>();
-            _definition.Parameters.Required.Add(name);
+            pars.Required ??= new List<string>();
+            pars.Required.Add(name);
         }
-
-        return this;
     }
 
     public FunctionDefinition Build() => _definition;

OpenAI.SDK/ObjectModels/ResponseModels/BaseResponse.cs

@@ -13,7 +13,7 @@ public record Error
 {
     [JsonPropertyName("code")] public string? Code { get; set; }
 
-    [JsonPropertyName("message")] public string? Message { get; set; }
+    [JsonPropertyName("message")] public object? Message { get; set; }
 
     [JsonPropertyName("param")] public string? Param { get; set; }