Generate text responses using Gemini API with external function calls in a chat scenario

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const {
  VertexAI,
  FunctionDeclarationSchemaType,
} = require('@google-cloud/vertexai');

const functionDeclarations = [
  {
    function_declarations: [
      {
        name: 'get_current_weather',
        description: 'get weather in a given location',
        parameters: {
          type: FunctionDeclarationSchemaType.OBJECT,
          properties: {
            location: {type: FunctionDeclarationSchemaType.STRING},
            unit: {
              type: FunctionDeclarationSchemaType.STRING,
              enum: ['celsius', 'fahrenheit'],
            },
          },
          required: ['location'],
        },
      },
    ],
  },
];

const functionResponseParts = [
  {
    functionResponse: {
      name: 'get_current_weather',
      response: {name: 'get_current_weather', content: {weather: 'super nice'}},
    },
  },
];

/**
 * TODO(developer): Update these variables before running the sample.
 */
async function functionCallingStreamChat(
  projectId = 'PROJECT_ID',
  location = 'us-central1',
  model = 'gemini-1.5-flash-001'
) {
  // Initialize Vertex with your Cloud project and location
  const vertexAI = new VertexAI({project: projectId, location: location});

  // Instantiate the model
  const generativeModel = vertexAI.getGenerativeModel({
    model: model,
  });

  // Create a chat session and pass your function declarations
  const chat = generativeModel.startChat({
    tools: functionDeclarations,
  });

  const chatInput1 = 'What is the weather in Boston?';

  // This should include a functionCall response from the model
  const result1 = await chat.sendMessageStream(chatInput1);
  for await (const item of result1.stream) {
    console.log(item.candidates[0]);
  }
  await result1.response;

  // Send a follow up message with a FunctionResponse
  const result2 = await chat.sendMessageStream(functionResponseParts);
  for await (const item of result2.stream) {
    console.log(item.candidates[0]);
  }

  // This should include a text response from the model using the response content
  // provided above
  const response2 = await result2.response;
  console.log(response2.candidates[0].content.parts[0].text);
}

import vertexai

from vertexai.generative_models import (
    FunctionDeclaration,
    GenerationConfig,
    GenerativeModel,
    Part,
    Tool,
)

# TODO(developer): Update & uncomment below line
# PROJECT_ID = "your-project-id"

# Initialize Vertex AI
vertexai.init(project=PROJECT_ID, location="us-central1")

# Specify a function declaration and parameters for an API request
get_product_sku = "get_product_sku"
get_product_sku_func = FunctionDeclaration(
    name=get_product_sku,
    description="Get the SKU for a product",
    # Function parameters are specified in OpenAPI JSON schema format
    parameters={
        "type": "object",
        "properties": {
            "product_name": {"type": "string", "description": "Product name"}
        },
    },
)

# Specify another function declaration and parameters for an API request
get_store_location_func = FunctionDeclaration(
    name="get_store_location",
    description="Get the location of the closest store",
    # Function parameters are specified in JSON schema format
    parameters={
        "type": "object",
        "properties": {"location": {"type": "string", "description": "Location"}},
    },
)

# Define a tool that includes the above functions
retail_tool = Tool(
    function_declarations=[
        get_product_sku_func,
        get_store_location_func,
    ],
)

# Initialize Gemini model
model = GenerativeModel(
    model_name="gemini-1.5-flash-001",
    generation_config=GenerationConfig(temperature=0),
    tools=[retail_tool],
)

# Start a chat session
chat = model.start_chat()

# Send a prompt for the first conversation turn that should invoke the get_product_sku function
response = chat.send_message("Do you have the Pixel 8 Pro in stock?")

function_call = response.candidates[0].function_calls[0]
print(function_call)

# Check the function name that the model responded with, and make an API call to an external system
if function_call.name == get_product_sku:
    # Extract the arguments to use in your API call
    product_name = function_call.args["product_name"]  # noqa: F841

    # Here you can use your preferred method to make an API request to retrieve the product SKU, as in:
    # api_response = requests.post(product_api_url, data={"product_name": product_name})

    # In this example, we'll use synthetic data to simulate a response payload from an external API
    api_response = {"sku": "GA04834-US", "in_stock": "Yes"}

# Return the API response to Gemini, so it can generate a model response or request another function call
response = chat.send_message(
    Part.from_function_response(
        name=get_product_sku,
        response={
            "content": api_response,
        },
    ),
)
# Extract the text from the model response
print(response.text)

# Send a prompt for the second conversation turn that should invoke the get_store_location function
response = chat.send_message(
    "Is there a store in Mountain View, CA that I can visit to try it out?"
)

function_call = response.candidates[0].function_calls[0]
print(function_call)

# Check the function name that the model responded with, and make an API call to an external system
if function_call.name == "get_store_location":
    # Extract the arguments to use in your API call
    location = function_call.args["location"]  # noqa: F841

    # Here you can use your preferred method to make an API request to retrieve store location closest to the user, as in:
    # api_response = requests.post(store_api_url, data={"location": location})

    # In this example, we'll use synthetic data to simulate a response payload from an external API
    api_response = {"store": "2000 N Shoreline Blvd, Mountain View, CA 94043, US"}

# Return the API response to Gemini, so it can generate a model response or request another function call
response = chat.send_message(
    Part.from_function_response(
        name="get_store_location",
        response={
            "content": api_response,
        },
    ),
)

# Extract the text from the model response
print(response.text)
# Example response:
# name: "get_product_sku"
# args {
#   fields { key: "product_name" value {string_value: "Pixel 8 Pro" }
#   }
# }
# Yes, we have the Pixel 8 Pro in stock.
# name: "get_store_location"
# args {
#   fields { key: "location" value { string_value: "Mountain View, CA" }
#   }
# }
# Yes, there is a store located at 2000 N Shoreline Blvd, Mountain View, CA 94043, US.