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Flask - JWT 認證

發布於 更新於
作者 Ned Hsu 6 分鐘閱讀

目標

  • 安裝並配置 PyJWT
  • 實現基於 JWT 的認證
  • 更新Blog API 使用 token 進行身份驗證

步驟

  1. 準備環境

    • 繼續使用 flask_api/ 項目結構，激活虛擬環境：
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      # Windows: flask_api_env\Scripts\activate
# macOS/Linux: source flask_api_env/bin/activate
    • 安裝 PyJWT：
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      pip install pyjwt

  2. 移除 Flask-HTTPAuth

    • 我們將替換 Flask-HTTPAuth，因此先移除相關依賴，但保留密碼字段。

  3. 更新應用配置

    • 修改 app/config.py，確保 SECRET_KEY 可用於 JWT 簽名：

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      import os
from dotenv import load_dotenv

load_dotenv()

class Config:
    SECRET_KEY = os.getenv('SECRET_KEY', 'default-secret-key')
    SQLALCHEMY_TRACK_MODIFICATIONS = False

class DevelopmentConfig(Config):
    DEBUG = True
    SQLALCHEMY_DATABASE_URI = os.getenv('DATABASE_URL', 'sqlite:///blog_dev.db')

class TestingConfig(Config):
    TESTING = True
    SQLALCHEMY_DATABASE_URI = os.getenv('DATABASE_URL', 'sqlite:///blog_test.db')
    WTF_CSRF_ENABLED = False

class ProductionConfig(Config):
    DEBUG = False
    SQLALCHEMY_DATABASE_URI = os.getenv('DATABASE_URL', 'sqlite:///blog_prod.db')

config_map = {
    'development': DevelopmentConfig,
    'testing': TestingConfig,
    'production': ProductionConfig
}

    • 確保 .env 中有 SECRET_KEY：

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      FLASK_ENV=development
SECRET_KEY=your-very-secret-key
DATABASE_URL=sqlite:///blog.db

  4. 實現 JWT 認證

    • 修改 app/init.py，添加 JWT 工具函數：

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      from flask import Flask, jsonify, g
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
import jwt
from functools import wraps
from .routes.v1.todos import todos_bp as todos_v1_bp
from .routes.v1.users import users_bp as users_v1_bp
from .routes.v1.posts import posts_bp as posts_v1_bp
from .routes.v2.todos import todos_bp as todos_v2_bp
from .routes.v2.posts import posts_bp as posts_v2_bp
from .config import config_map
import os

db = SQLAlchemy()
ma = Marshmallow()

def create_app():
    app = Flask(__name__)
    env = os.getenv('FLASK_ENV', 'development')
    app.config.from_object(config_map[env])
    db.init_app(app)
    ma.init_app(app)

    app.register_blueprint(todos_v1_bp, url_prefix='/api/v1')
    app.register_blueprint(users_v1_bp, url_prefix='/api/v1')
    app.register_blueprint(posts_v1_bp, url_prefix='/api/v1')
    app.register_blueprint(todos_v2_bp, url_prefix='/api/v2')
    app.register_blueprint(posts_v2_bp, url_prefix='/api/v2')

    @app.errorhandler(404)
    def not_found(error):
        return jsonify({'error': 'Not Found', 'message': str(error)}), 404

    @app.errorhandler(400)
    def bad_request(error):
        return jsonify({'error': 'Bad Request', 'message': str(error)}), 400

    @app.errorhandler(500)
    def internal_error(error):
        return jsonify({'error': 'Internal Server Error', 'message': 'Something went wrong on our end'}), 500

    with app.app_context():
        db.create_all()

    return app

# JWT 認證裝飾器
def login_required(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        from .models import User  # 避免循環導入
        token = request.headers.get('Authorization')
        if not token:
            abort(401, description='Missing token')
        try:
            if token.startswith('Bearer '):
                token = token[7:]  # 移除 "Bearer " 前綴
            data = jwt.decode(token, app.config['SECRET_KEY'], algorithms=['HS256'])
            user = User.query.get(data['user_id'])
            if not user:
                abort(401, description='Invalid token')
            g.current_user = user  # 存儲當前用戶
        except jwt.ExpiredSignatureError:
            abort(401, description='Token has expired')
        except jwt.InvalidTokenError:
            abort(401, description='Invalid token')
        return f(*args, **kwargs)
    return decorated_function

  5. 添加登錄端點

    • 修改 app/routes/v1/users.py，添加生成 JWT 的登錄路由：

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      from flask import Blueprint, jsonify, request, abort
from ...models import User
from ... import db
from ...schemas import user_schema, users_schema
import jwt
import datetime

users_bp = Blueprint('users_v1', __name__)

@users_bp.route('/users', methods=['GET'])
def get_users():
    users = User.query.all()
    return jsonify({'users': users_schema.dump(users)})

@users_bp.route('/users', methods=['POST'])
def create_user():
    if not request.is_json:
        abort(400, description='Request must be JSON')
    data = request.get_json()
    if 'username' not in data or 'password' not in data:
        abort(400, description='Missing username or password')
    if User.query.filter_by(username=data['username']).first():
        abort(400, description='Username already exists')
    user = User(username=data['username'], password=data['password'])
    db.session.add(user)
    db.session.commit()
    return jsonify(user_schema.dump(user)), 201

@users_bp.route('/login', methods=['POST'])
def login():
    if not request.is_json:
        abort(400, description='Request must be JSON')
    data = request.get_json()
    if 'username' not in data or 'password' not in data:
        abort(400, description='Missing username or password')
    user = User.query.filter_by(username=data['username']).first()
    if not user or user.password != data['password']:
        abort(401, description='Invalid credentials')
    token = jwt.encode({
        'user_id': user.id,
        'exp': datetime.datetime.utcnow() + datetime.timedelta(hours=24)  # Token 有效期 24 小時
    }, users_bp.app.config['SECRET_KEY'], algorithm='HS256')
    return jsonify({'token': token})

  6. 保護路由

    • 修改 app/routes/v1/posts.py，使用 JWT 認證：

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      from flask import Blueprint, jsonify, request, abort, g
from ...models import Post, User
from ... import db, login_required
from ...schemas import post_schema, posts_schema

posts_bp = Blueprint('posts_v1', __name__)

@posts_bp.route('/posts', methods=['GET'])
def get_posts():
    user_id = request.args.get('user_id', type=int)
    query = Post.query
    if user_id:
        query = query.filter_by(user_id=user_id)
    posts = query.all()
    return jsonify({'posts': posts_schema.dump(posts)})

@posts_bp.route('/posts/<int:post_id>', methods=['GET'])
def get_post(post_id):
    post = Post.query.get_or_404(post_id, description='Post not found')
    return jsonify(post_schema.dump(post))

@posts_bp.route('/posts', methods=['POST'])
@login_required
def create_post():
    if not request.is_json:
        abort(400, description='Request must be JSON')
    data = request.get_json()
    if 'title' not in data or 'content' not in data:
        abort(400, description='Missing title or content')
    post = Post(
        title=data['title'],
        content=data['content'],
        user_id=g.current_user.id  # 使用當前認證用戶
    )
    db.session.add(post)
    db.session.commit()
    return jsonify(post_schema.dump(post)), 201

@posts_bp.route('/posts/<int:post_id>', methods=['PUT'])
@login_required
def update_post(post_id):
    post = Post.query.get_or_404(post_id, description='Post not found')
    if post.user_id != g.current_user.id:
        abort(403, description='You can only edit your own posts')
    if not request.is_json:
        abort(400, description='Request must be JSON')
    data = request.get_json()
    if 'title' in data:
        post.title = data['title']
    if 'content' in data:
        post.content = data['content']
    db.session.commit()
    return jsonify(post_schema.dump(post)), 200

@posts_bp.route('/posts/<int:post_id>', methods=['DELETE'])
@login_required
def delete_post(post_id):
    post = Post.query.get_or_404(post_id, description='Post not found')
    if post.user_id != g.current_user.id:
        abort(403, description='You can only delete your own posts')
    db.session.delete(post)
    db.session.commit()
    return jsonify({'message': 'Post deleted'}), 200

  7. 運行應用

    • 運行：
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      python run.py

  8. 測試 API

    • 使用 Postman 測試：
      • POST /api/v1/users：
        • Body：{"username": "alice", "password": "1234"}
      • POST /api/v1/login：
        • Body：{"username": "alice", "password": "1234"}
        • 預期響應：{"token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9..."}
      • POST /api/v1/posts（未認證）：
        • Body：{"title": "My Post", "content": "Hello"}
        • 預期響應：401
      • POST /api/v1/posts（認證）：
        • Headers：Authorization: Bearer <token>
        • Body：{"title": "My Post", "content": "Hello"}
        • 預期響應：201
      • PUT /api/v1/posts/1（錯誤用戶）：
        • 用另一用戶的 token，應返回 403。

  9. 作業

    • 在 v2 的 posts 路由中實現相同的 JWT 認證。
    • 添加一個端點 GET /api/v1/me，返回當前用戶的信息（使用 g.current_user）。

注意事項

  • Token 過期後需重新登錄獲取新 token。
  • 目前密碼仍是明文，下一天會加密。
  • 在 Postman 中，將 token 添加到 Headers 的 Authorization 字段，格式為 Bearer <token>。
Software, Python
Flask
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