Your First Gemini API Call

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Your First Gemini API Call — Gemini API & Google AI

Install the SDK

pip install google-generativeai      # Python
npm install @google/generative-ai    # JavaScript

Get a free key in Google AI Studio and put it in the GEMINI_API_KEY environment variable. Never hardcode the key in your repo, and never call Gemini directly from the browser — the key leaks.

Minimal call in Python

import os
import google.generativeai as genai

genai.configure(api_key=os.environ["GEMINI_API_KEY"])

model = genai.GenerativeModel("gemini-2.0-flash")
response = model.generate_content("Explain closures in JS in 3 sentences")
print(response.text)

Same in JavaScript

import { GoogleGenerativeAI } from "@google/generative-ai";

const genAI = new GoogleGenerativeAI(process.env.GEMINI_API_KEY);
const model = genAI.getGenerativeModel({ model: "gemini-2.0-flash" });

const result = await model.generateContent("Explain closures in 3 sentences");
console.log(result.response.text());

What's inside the response

The GenerateContentResponse object contains:

candidates — a list of response variants (usually one). Inside is content.parts — an array of parts.
response.text — a convenience helper that joins the text parts of the first candidate. If the candidate was filtered, accessing .text raises an exception.
candidates[0].finish_reason — STOP, MAX_TOKENS, SAFETY, RECITATION.
prompt_feedback — why the prompt may have been blocked (block_reason).
usage_metadata — prompt_token_count, candidates_token_count, total_token_count for cost accounting.

Safe reading

cand = response.candidates[0]
if cand.finish_reason.name == "SAFETY":
    print("Response blocked by safety filter")
else:
    text = "".join(p.text for p in cand.content.parts if p.text)
    print(text, response.usage_metadata.total_token_count)

Don't read response.text blindly: on finish_reason == SAFETY or an empty candidate it raises, not returns an empty string. In production always check finish_reason and prompt_feedback.

Сообщить об ошибке

Квиз — 4 вопроса

Install the SDK

Minimal call in Python

Same in JavaScript

What's inside the response

Safe reading