Allow structured outputs via function calling (sashabaranov#828)

Author: greysteil

Diff for: api_integration_test.go

@@ -239,3 +239,79 @@ func TestChatCompletionResponseFormat_JSONSchema(t *testing.T) {
 		}
 	}
 }
+
+func TestChatCompletionStructuredOutputsFunctionCalling(t *testing.T) {
+	apiToken := os.Getenv("OPENAI_TOKEN")
+	if apiToken == "" {
+		t.Skip("Skipping testing against production OpenAI API. Set OPENAI_TOKEN environment variable to enable it.")
+	}
+
+	var err error
+	c := openai.NewClient(apiToken)
+	ctx := context.Background()
+
+	resp, err := c.CreateChatCompletion(
+		ctx,
+		openai.ChatCompletionRequest{
+			Model: openai.GPT4oMini,
+			Messages: []openai.ChatCompletionMessage{
+				{
+					Role: openai.ChatMessageRoleSystem,
+					Content: "Please enter a string, and we will convert it into the following naming conventions:" +
+						"1. PascalCase: Each word starts with an uppercase letter, with no spaces or separators." +
+						"2. CamelCase: The first word starts with a lowercase letter, " +
+						"and subsequent words start with an uppercase letter, with no spaces or separators." +
+						"3. KebabCase: All letters are lowercase, with words separated by hyphens `-`." +
+						"4. SnakeCase: All letters are lowercase, with words separated by underscores `_`.",
+				},
+				{
+					Role:    openai.ChatMessageRoleUser,
+					Content: "Hello World",
+				},
+			},
+			Tools: []openai.Tool{
+				{
+					Type: openai.ToolTypeFunction,
+					Function: &openai.FunctionDefinition{
+						Name:   "display_cases",
+						Strict: true,
+						Parameters: &jsonschema.Definition{
+							Type: jsonschema.Object,
+							Properties: map[string]jsonschema.Definition{
+								"PascalCase": {
+									Type: jsonschema.String,
+								},
+								"CamelCase": {
+									Type: jsonschema.String,
+								},
+								"KebabCase": {
+									Type: jsonschema.String,
+								},
+								"SnakeCase": {
+									Type: jsonschema.String,
+								},
+							},
+							Required:             []string{"PascalCase", "CamelCase", "KebabCase", "SnakeCase"},
+							AdditionalProperties: false,
+						},
+					},
+				},
+			},
+			ToolChoice: openai.ToolChoice{
+				Type: openai.ToolTypeFunction,
+				Function: openai.ToolFunction{
+					Name: "display_cases",
+				},
+			},
+		},
+	)
+	checks.NoError(t, err, "CreateChatCompletion (use structured outputs response) returned error")
+	var result = make(map[string]string)
+	err = json.Unmarshal([]byte(resp.Choices[0].Message.ToolCalls[0].Function.Arguments), &result)
+	checks.NoError(t, err, "CreateChatCompletion (use structured outputs response) unmarshal error")
+	for _, key := range []string{"PascalCase", "CamelCase", "KebabCase", "SnakeCase"} {
+		if _, ok := result[key]; !ok {
+			t.Errorf("key:%s does not exist.", key)
+		}
+	}
+}

Diff for: chat.go

@@ -264,6 +264,7 @@ type ToolFunction struct {
 type FunctionDefinition struct {
 	Name        string `json:"name"`
 	Description string `json:"description,omitempty"`
+	Strict      bool   `json:"strict,omitempty"`
 	// Parameters is an object describing the function.
 	// You can pass json.RawMessage to describe the schema,
 	// or you can pass in a struct which serializes to the proper JSON schema.

Diff for: chat_test.go

@@ -277,6 +277,32 @@ func TestChatCompletionsFunctions(t *testing.T) {
 		})
 		checks.NoError(t, err, "CreateChatCompletion with functions error")
 	})
+	t.Run("StructuredOutputs", func(t *testing.T) {
+		type testMessage struct {
+			Count int      `json:"count"`
+			Words []string `json:"words"`
+		}
+		msg := testMessage{
+			Count: 2,
+			Words: []string{"hello", "world"},
+		}
+		_, err := client.CreateChatCompletion(context.Background(), openai.ChatCompletionRequest{
+			MaxTokens: 5,
+			Model:     openai.GPT3Dot5Turbo0613,
+			Messages: []openai.ChatCompletionMessage{
+				{
+					Role:    openai.ChatMessageRoleUser,
+					Content: "Hello!",
+				},
+			},
+			Functions: []openai.FunctionDefinition{{
+				Name:       "test",
+				Strict:     true,
+				Parameters: &msg,
+			}},
+		})
+		checks.NoError(t, err, "CreateChatCompletion with functions error")
+	})
 }
 
 func TestAzureChatCompletions(t *testing.T) {