详解Python Flask框架的安装及应用_python_

mkdir myproject cd myproject python3 -m venv venv 

. venv/bin/activate 

pip install Flask 

from flask import Flask app = Flask(__name__) @app.route("/") def hello_world(): return "
Hello, World!
" 

export FLASK_APP=hello flask run 

@app.route('/') def index(): return 'Index Page' @app.route('/hello') def hello(): return 'Hello, World' @app.route('/user/') def show_user_profile(username): # show the user profile for that user return f'User {escape(username)}' @app.route('/post/') def show_post(post_id): # show the post with the given id, the id is an integer return f'Post {post_id}' @app.route('/path/') def show_subpath(subpath): # show the subpath after /path/ return f'Subpath {escape(subpath)}' 

@app.route('/login', methods=['GET', 'POST']) def login(): if request.method == 'POST': else: 

$ git clone https://github.com/pallets/flask $ cd flask $ cd examples/tutorial 

def create_app(test_config=None): """Create and configure an instance of the Flask application.""" # 1-创建一个 Flask 实例 # 并设置一些 APP 需要用到的参数 app = Flask(__name__, instance_relative_config=True) app.config.from_mapping( # a default secret that should be overridden by instance config SECRET_KEY="dev", # store the database in the instance folder DATABASE=os.path.join(app.instance_path, "flaskr.sqlite"), ) # 2-测试用的 if test_config is None: # load the instance config, if it exists, when not testing app.config.from_pyfile("config.py", silent=True) else: # load the test config if passed in app.config.update(test_config) # 3-创建一个文件夹，用来存 DB 运行时的产生的文件 # ensure the instance folder exists try: os.makedirs(app.instance_path) except OSError: pass @app.route("/hello") def hello(): return "Hello, World!" # register the database commands # 3.3 数据库设置（为 flask 新增一个 init_db 命令，这样直接敲 flask init_db 就能生成表） from flaskr import db db.init_app(app) # apply the blueprints to the app # #### 3.4 蓝图和视图（基于蓝图来管理组织视图，视图注册到蓝图，蓝图注册到应用） from flaskr import auth, blog app.register_blueprint(auth.bp) app.register_blueprint(blog.bp) # make url_for('index') == url_for('blog.index') # in another app, you might define a separate main index here with # app.route, while giving the blog blueprint a url_prefix, but for # the tutorial the blog will be the main index app.add_url_rule("/", endpoint="index") return app 

DROP TABLE IF EXISTS user; DROP TABLE IF EXISTS post; CREATE TABLE user ( id INTEGER PRIMARY KEY AUTOINCREMENT, username TEXT UNIQUE NOT NULL, password TEXT NOT NULL ); CREATE TABLE post ( id INTEGER PRIMARY KEY AUTOINCREMENT, author_id INTEGER NOT NULL, created TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP, title TEXT NOT NULL, body TEXT NOT NULL, FOREIGN KEY (author_id) REFERENCES user (id) ); 

def get_db(): """Connect to the application's configured database. The connection is unique for each request and will be reused if this is called again. """ if "db" not in g: g.db = sqlite3.connect( current_app.config["DATABASE"], detect_types=sqlite3.PARSE_DECLTYPES ) g.db.row_factory = sqlite3.Row return g.db def close_db(e=None): """If this request connected to the database, close the connection. """ db = g.pop("db", None) if db is not None: db.close() 

def init_db(): """Clear existing data and create new tables.""" db = get_db() # 获取数据库（如果没有则创建） # 读取 schema.sql 中的 SQL 命令，并用 db.executescript 执行 SQL 命令 with current_app.open_resource("schema.sql") as f: db.executescript(f.read().decode("utf8")) 

@click.command("init-db") @with_appcontext def init_db_command(): """Clear existing data and create new tables.""" init_db() click.echo("Initialized the database.") def init_app(app): """Register database functions with the Flask app. This is called by the application factory. """ app.teardown_appcontext(close_db) # 在返回响应后进行清理时调用该函数 app.cli.add_command(init_db_command) # 添加一个可以用flask命令调用的新命令 

bp = Blueprint("auth", __name__, url_prefix="/auth") # in auth.py bp = Blueprint("blog", __name__) # in blog.py 

@bp.route("/register", methods=("GET", "POST")) def register(): ... @bp.route("/login", methods=("GET", "POST")) def login(): ... @bp.route("/logout") def logout(): 

@bp.route("/") def index(): ... @bp.route("/create", methods=("GET", "POST")) @login_required def create(): ... @bp.route("//update", methods=("GET", "POST")) @login_required def update(id): ... @bp.route("//delete", methods=("POST",)) @login_required def delete(id): ... 

if error is None: # store the user id in a new session and return to the index session.clear() session["user_id"] = user["id"] return redirect(url_for("index")) 

@bp.before_app_request def load_logged_in_user(): user_id = session.get('user_id') if user_id is 
                
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