signly_google 0.1.1

Flutter plugin-style package that performs one-shot Google Sign-In for Android and iOS and returns only the requested token.

🚀 signly_google

A modern Google Sign-In wrapper for Flutter using the latest SDK.

• ✨ Simple API
• 🔐 Secure token flows
• 📱 Mobile focused
• 🧠 Backend ready

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✅ Platform support

Platform	Supported
Android	✅
iOS	✅
Web	❌
macOS	❌
Windows	❌
Linux	❌

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📦 What you get

Token / Data	Purpose
🪪 idToken (JWT)	Authenticate the user on your backend
🔁 serverAuthCode	Exchange on backend for refresh token flow
🌐 accessToken	Call Google APIs directly
👤 Profile	Access user email, name, avatar

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🏗️ GCP setup

1) OAuth Consent Screen

Open: Google Auth Overview

Configure:

• ✔ App name
• ✔ User support email
• ✔ Audience
• ✔ Developer contact email

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2) Android OAuth Client

Open: Google Cloud Credentials

Create OAuth client of type Android and provide:

• 📦 Package name
• 🔑 SHA-1 fingerprint

Notes:

• ✅ Used for Google handshake
• 🚫 Not passed directly in Flutter code

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3) iOS OAuth Client

Open: Google Cloud Credentials

Create OAuth client of type iOS and provide:

• 📦 Bundle ID

Then add in ios/Runner/Info.plist:

<key>GIDClientID</key>
<string>YOUR_CLIENT_ID.apps.googleusercontent.com</string>

<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>com.googleusercontent.apps.YOUR_CLIENT_ID</string>
    </array>
  </dict>
</array>

🔁 URL scheme sends users back to your app after login.

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4) Web OAuth Client (important for backend flow)

Open: Google Cloud Credentials

Create OAuth client of type Web Application.

This value becomes your serverClientId, used for:

• ✅ idToken audience
• ✅ serverAuthCode
• ✅ backend refresh-token flow

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🔐 Token meanings

🪪 idToken

• JWT signed by Google
• Contains user identity claims

🌐 accessToken

• Used to call Google APIs
• ⏳ Short-lived and expires automatically

🔁 serverAuthCode

• One-time authorization code
• Exchanged on backend for long-term refresh flow

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📱 Flutter usage

import 'package:signly_google/signly_google.dart';

final client = SignlyGoogleClient();

final result = await client.signIn(
  GoogleSignInRequest(
    clientId: 'YOUR_PLATFORM_CLIENT_ID',
    serverClientId: 'YOUR_WEB_CLIENT_ID',
    scopes: ['email', 'profile'],
    requestedTokenType: GoogleRequestedTokenType.<token_type>,
  ),
);

Access returned values

result.requestedToken
result.requestedTokenType.name
result.userId
result.userData.email
result.userData.displayName
result.userData.photoUrl

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🧠 Recommended production flow

• 📱 Flutter obtains idToken + serverAuthCode
• 🖥️ Backend exchanges auth code and stores refresh token securely
• ♻️ Backend refreshes access as needed

🚫 Avoid relying only on mobile-side accessToken for long-lived sessions.

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📄 License

MIT