GoogleAIGeminiChatGenerator

This component enables chat completion using Google Gemini models.

Deprecation Notice

This integration uses the deprecated google-generativeai SDK, which will lose support after August 2025.

We recommend switching to the new GoogleGenAIChatGenerator integration instead.

Most common position in a pipeline	After a ChatPromptBuilder
Mandatory init variables	api_key: A Google AI Studio API key. Can be set with GOOGLE_API_KEY env var.
Mandatory run variables	messages: A list of ChatMessage objects representing the chat
Output variables	replies: A list of alternative replies of the model to the input chat
API reference	Google AI
GitHub link	https://github.com/deepset-ai/haystack-core-integrations/tree/main/integrations/google_ai
Package name	google-ai-haystack

GoogleAIGeminiChatGenerator supports gemini-2.5-pro-exp-03-25, gemini-2.0-flash, gemini-1.5-pro, and gemini-1.5-flash models.

For available models, see https://ai.google.dev/gemini-api/docs/models/gemini.

Parameters Overview

GoogleAIGeminiChatGenerator uses a Google Studio API key for authentication. You can write this key in an api_key parameter or as a GOOGLE_API_KEY environment variable (recommended).

To get an API key, visit the Google AI Studio website.

Streaming

This Generator supports streaming the tokens from the LLM directly in output. To do so, pass a function to the streaming_callback init parameter.

Usage

To begin working with GoogleAIGeminiChatGenerator, install the google-ai-haystack package:

shell

pip install google-ai-haystack

On its own

Basic usage:

python

import os
from haystack.dataclasses import ChatMessage
from haystack_integrations.components.generators.google_ai import GoogleAIGeminiChatGenerator

os.environ["GOOGLE_API_KEY"] = "<MY_API_KEY>"
gemini_chat = GoogleAIGeminiChatGenerator()

messages = [ChatMessage.from_user("Tell me the name of a movie")]
res = gemini_chat.run(messages)

print(res["replies"][0].text)
>>> The Shawshank Redemption

messages += [res["replies"], ChatMessage.from_user("Who's the main actor?")]
res = gemini_chat.run(messages)

print(res["replies"][0].text)
>>> Tim Robbins

When chatting with Gemini, you can also easily use function calls. First, define the function locally and convert into a Tool:

python

from typing import Annotated
from haystack.tools import create_tool_from_function


# example function to get the current weather
def get_current_weather(
    location: Annotated[
        str,
        "The city for which to get the weather, e.g. 'San Francisco'",
    ] = "Munich",
    unit: Annotated[str, "The unit for the temperature, e.g. 'celsius'"] = "celsius",
) -> str:
    return f"The weather in {location} is sunny. The temperature is 20 {unit}."


tool = create_tool_from_function(get_current_weather)

Create a new instance of GoogleAIGeminiChatGenerator to set the tools and a ToolInvoker to invoke the tools.

python

import os
from haystack_integrations.components.generators.google_ai import (
    GoogleAIGeminiChatGenerator,
)
from haystack.components.tools import ToolInvoker

os.environ["GOOGLE_API_KEY"] = "<MY_API_KEY>"

gemini_chat = GoogleAIGeminiChatGenerator(model="gemini-2.0-flash", tools=[tool])

tool_invoker = ToolInvoker(tools=[tool])

And then ask a question:

python

from haystack.dataclasses import ChatMessage

messages = [ChatMessage.from_user("What is the temperature in celsius in Berlin?")]
res = gemini_chat.run(messages=messages)

print(res["replies"][0].tool_calls)
>>> [ToolCall(tool_name='get_current_weather',
>>>           arguments={'unit': 'celsius', 'location': 'Berlin'}, id=None)]

tool_messages = tool_invoker.run(messages=replies)["tool_messages"]
messages = user_message + replies + tool_messages

messages += res["replies"][0] + [ChatMessage.from_function(content=weather, name="get_current_weather")]

final_replies = gemini_chat.run(messages=messages)["replies"]
print(final_replies[0].text)
>>> The temperature in Berlin is 20 degrees Celsius.

In a pipeline

python

import os
from haystack.components.builders import ChatPromptBuilder
from haystack.dataclasses import ChatMessage
from haystack import Pipeline
from haystack_integrations.components.generators.google_ai import GoogleAIGeminiChatGenerator

# no parameter init, we don't use any runtime template variables
prompt_builder = ChatPromptBuilder()

os.environ["GOOGLE_API_KEY"] = "<MY_API_KEY>"
gemini_chat = GoogleAIGeminiChatGenerator()

pipe = Pipeline()
pipe.add_component("prompt_builder", prompt_builder)
pipe.add_component("gemini", gemini_chat)
pipe.connect("prompt_builder.prompt", "gemini.messages")

location = "Rome"
messages = [ChatMessage.from_user("Tell me briefly about {{location}} history")]
res = pipe.run(data={"prompt_builder": {"template_variables":{"location": location}, "template": messages}})

print(res)

>>> - **753 B.C.:** Traditional date of the founding of Rome by Romulus and Remus.
>>> - **509 B.C.:** Establishment of the Roman Republic, replacing the Etruscan monarchy.
>>> - **492-264 B.C.:** Series of wars against neighboring tribes, resulting in the expansion of the Roman Republic's territory.
>>> - **264-146 B.C.:** Three Punic Wars against Carthage, resulting in the destruction of Carthage and the Roman Republic becoming the dominant power in the Mediterranean.
>>> - **133-73 B.C.:** Series of civil wars and slave revolts, leading to the rise of Julius Caesar.
>>> - **49 B.C.:** Julius Caesar crosses the Rubicon River, starting the Roman Civil War.
>>> - **44 B.C.:** Julius Caesar is assassinated, leading to the Second Triumvirate of Octavian, Mark Antony, and Lepidus.
>>> - **31 B.C.:** Battle of Actium, where Octavian defeats Mark Antony and Cleopatra, becoming the sole ruler of Rome.
>>> - **27 B.C.:** The Roman Republic is transformed into the Roman Empire, with Octavian becoming the first Roman emperor, known as Augustus.
>>> - **1st century A.D.:** The Roman Empire reaches its greatest extent, stretching from Britain to Egypt.
>>> - **3rd century A.D.:** The Roman Empire begins to decline, facing internal instability, invasions by Germanic tribes, and the rise of Christianity.
>>> - **476 A.D.:** The last Western Roman emperor, Romulus Augustulus, is overthrown by the Germanic leader Odoacer, marking the end of the Roman Empire in the West.