func functionCallsChat()

in vertexai/function-calling/functioncalling.go [42:199]
125 lines of code
20 McCabe index (conditional complexity)

func functionCallsChat(w io.Writer, projectID, location, modelName string) error {
	// location := "us-central1"
	// modelName := "gemini-2.0-flash-001"
	ctx := context.Background()
	client, err := genai.NewClient(ctx, projectID, location)
	if err != nil {
		return fmt.Errorf("unable to create client: %w", err)
	}
	defer client.Close()

	model := client.GenerativeModel(modelName)

	// Build an OpenAPI schema, in memory
	paramsProduct := &genai.Schema{
		Type: genai.TypeObject,
		Properties: map[string]*genai.Schema{
			"productName": {
				Type:        genai.TypeString,
				Description: "Product name",
			},
		},
	}
	fundeclProductInfo := &genai.FunctionDeclaration{
		Name:        "getProductSku",
		Description: "Get the SKU for a product",
		Parameters:  paramsProduct,
	}
	paramsStore := &genai.Schema{
		Type: genai.TypeObject,
		Properties: map[string]*genai.Schema{
			"location": {
				Type:        genai.TypeString,
				Description: "Location",
			},
		},
	}
	fundeclStoreLocation := &genai.FunctionDeclaration{
		Name:        "getStoreLocation",
		Description: "Get the location of the closest store",
		Parameters:  paramsStore,
	}
	model.Tools = []*genai.Tool{
		{FunctionDeclarations: []*genai.FunctionDeclaration{
			fundeclProductInfo,
			fundeclStoreLocation,
		}},
	}
	model.SetTemperature(0.0)

	chat := model.StartChat()

	// Send a prompt for the first conversation turn that should invoke the getProductSku function
	prompt := "Do you have the Pixel 8 Pro in stock?"
	fmt.Fprintf(w, "Question: %s\n", prompt)
	resp, err := chat.SendMessage(ctx, genai.Text(prompt))
	if err != nil {
		return err
	}
	if len(resp.Candidates) == 0 ||
		len(resp.Candidates[0].Content.Parts) == 0 {
		return errors.New("empty response from model")
	}

	// The model has returned a function call to the declared function `getProductSku`
	// with a value for the argument `productName`.
	jsondata, err := json.MarshalIndent(resp.Candidates[0].Content.Parts[0], "\t", "  ")
	if err != nil {
		return fmt.Errorf("json.MarshalIndent: %w", err)
	}
	fmt.Fprintf(w, "function call generated by the model:\n\t%s\n", string(jsondata))

	// Create a function call response, to simulate the result of a call to a
	// real service
	funresp := &genai.FunctionResponse{
		Name: "getProductSku",
		Response: map[string]any{
			"sku":      "GA04834-US",
			"in_stock": "yes",
		},
	}
	jsondata, err = json.MarshalIndent(funresp, "\t", "  ")
	if err != nil {
		return fmt.Errorf("json.MarshalIndent: %w", err)
	}
	fmt.Fprintf(w, "function call response sent to the model:\n\t%s\n\n", string(jsondata))

	// And provide the function call response to the model
	resp, err = chat.SendMessage(ctx, funresp)
	if err != nil {
		return err
	}
	if len(resp.Candidates) == 0 ||
		len(resp.Candidates[0].Content.Parts) == 0 {
		return errors.New("empty response from model")
	}

	// The model has taken the function call response as input, and has
	// reformulated the response to the user.
	jsondata, err = json.MarshalIndent(resp.Candidates[0].Content.Parts[0], "\t", "  ")
	if err != nil {
		return fmt.Errorf("json.MarshalIndent: %w", err)
	}
	fmt.Fprintf(w, "Answer generated by the model:\n\t%s\n\n", string(jsondata))

	// Send a prompt for the second conversation turn that should invoke the getStoreLocation function
	prompt2 := "Is there a store in Mountain View, CA that I can visit to try it out?"
	fmt.Fprintf(w, "Question: %s\n", prompt)

	resp, err = chat.SendMessage(ctx, genai.Text(prompt2))
	if err != nil {
		return err
	}
	if len(resp.Candidates) == 0 ||
		len(resp.Candidates[0].Content.Parts) == 0 {
		return errors.New("empty response from model")
	}

	// The model has returned a function call to the declared function `getStoreLocation`
	// with a value for the argument `store`.
	jsondata, err = json.MarshalIndent(resp.Candidates[0].Content.Parts[0], "\t", "  ")
	if err != nil {
		return fmt.Errorf("json.MarshalIndent: %w", err)
	}
	fmt.Fprintf(w, "function call generated by the model:\n\t%s\n", string(jsondata))

	// Create a function call response, to simulate the result of a call to a
	// real service
	funresp = &genai.FunctionResponse{
		Name: "getStoreLocation",
		Response: map[string]any{
			"store": "2000 N Shoreline Blvd, Mountain View, CA 94043, US",
		},
	}
	jsondata, err = json.MarshalIndent(funresp, "\t", "  ")
	if err != nil {
		return fmt.Errorf("json.MarshalIndent: %w", err)
	}
	fmt.Fprintf(w, "function call response sent to the model:\n\t%s\n\n", string(jsondata))

	// And provide the function call response to the model
	resp, err = chat.SendMessage(ctx, funresp)
	if err != nil {
		return err
	}
	if len(resp.Candidates) == 0 ||
		len(resp.Candidates[0].Content.Parts) == 0 {
		return errors.New("empty response from model")
	}

	// The model has taken the function call response as input, and has
	// reformulated the response to the user.
	jsondata, err = json.MarshalIndent(resp.Candidates[0].Content.Parts[0], "\t", "  ")
	if err != nil {
		return fmt.Errorf("json.MarshalIndent: %w", err)
	}
	fmt.Fprintf(w, "Answer generated by the model:\n\t%s\n\n", string(jsondata))
	return nil
}