Update project metadata and add new JSON Schema properties: support array-like type of property to support optional props https://platform.openai.com/docs/guides/structured-outputs#all-fields-must-be-required

Author: repko-artem

OpenAI.SDK/ObjectModels/Converters.cs

@@ -89,4 +89,51 @@ public override void Write(Utf8JsonWriter writer, AssistantsApiToolChoiceOneOfTy
             writer.WriteNullValue();
         }
     }
-}
+}
+
+public class SingleOrArrayToListConverter : JsonConverter<List<string?>>
+{
+    public override List<string?>? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) {
+        switch (reader.TokenType) {
+            case JsonTokenType.String:
+                return [reader.GetString()];
+            case JsonTokenType.StartArray:
+            {
+                var list = new List<string?>();
+                while (reader.Read() && reader.TokenType != JsonTokenType.EndArray) {
+                    switch (reader.TokenType) {
+                        case JsonTokenType.String:
+                            list.Add(reader.GetString());
+                            break;
+                        case JsonTokenType.Null:
+                            list.Add(null);
+                            break;
+                        default:
+                            throw new JsonException($"Unexpected token in type array: {reader.TokenType}");
+                    }
+                }
+                return list;
+            }
+            default:
+                throw new JsonException($"Unexpected token parsing type: {reader.TokenType}");
+        }
+    }
+
+    public override void Write(Utf8JsonWriter writer, List<string?>? value, JsonSerializerOptions options) {
+        if (value == null || value.Count == 0) {
+            writer.WriteNullValue();
+        } else if (value.Count == 1) {
+            writer.WriteStringValue(value[0]);
+        } else {
+            writer.WriteStartArray();
+            foreach (var item in value) {
+                if (item == null) {
+                    writer.WriteNullValue();
+                } else {
+                    writer.WriteStringValue(item);
+                }
+            }
+            writer.WriteEndArray();
+        }
+    }
+}

OpenAI.SDK/ObjectModels/SharedModels/FunctionParameters.cs

@@ -20,10 +20,26 @@ public enum FunctionObjectTypes
     }
 
     /// <summary>
-    ///     Function parameter object type. Default value is "object".
+    ///     Property's type as a string. Only one: <see cref="TypeList"/> or <see cref="Type"/> should be set.
+    /// </summary>
+    [JsonIgnore]
+    public string? Type {
+        get => TypeList?.Count != 1 ? null : TypeList[0];
+        set {
+            if (value == null) {
+                TypeList = null;
+                return;
+            }
+            TypeList = [value];
+        }
+    }
+
+    /// <summary>
+    ///     Property's type as a list of strings. Only one: <see cref="TypeList"/> or <see cref="Type"/> should be set.
     /// </summary>
     [JsonPropertyName("type")]
-    public string? Type { get; set; }
+    [JsonConverter(typeof(SingleOrArrayToListConverter))]
+    public IList<string?>? TypeList { get; set; }
 
     /// <summary>
     ///     An instance validates successfully against this keyword if its value is equal to the value of the keyword