[Python] Flask 基本教學

程式語言：Python
Package：
flask
flask_script
flask_sqlalchemy
flask_admin
flask_login
Flask 官方網站
GitHub

功能：架站

最簡易的程式碼
  1. # hello.py
  2. from flask import Flask
  3. app = Flask(__name__)
  4.  
  5. @app.route('/')
  6. def hello_world():
  7.     return 'Hello, World!'
運行方法 
# linux
#export FLASK_APP=hello.py
# window
set FLASK_APP=hello.py
python -m flask run

Flask-Script
提供外部指令，例：python manage.py runserver --debug 
  1. # hello.py
  2. from flask import Flask
  3. app = Flask(__name__)
  4.  
  5. @app.route('/')
  6. def hello_world():
  7.     return 'Hello, World!'
  1. # manage.py
  2. from flask_script import Manager
  3. from hello import app
  4.  
  5. manager = Manager(app)
  6.  
  7. # 自定指令
  8. @manager.command
  9. def hello():
  10.     """Print hello"""
  11.     print("hello")
  12.  
  13. if __name__ == "__main__":
  14.     manager.run()
運行方法 
# 可確認有哪些指令，自定的指令也會出現
python manage.py

# 運行 server
python manage.py runserver

# 運行 server 並啟動 debug，可輸入 pin 直接 debug
python manage.py runserver --debug

# 運行 shell
python manage.py shell

Flask-SQLAlchemy
ORM 工具，可直接用 python 控制資料庫 
  1. # hello.py
  2. from flask import Flask
  3. app = Flask(__name__)
  4.  
  5. @app.route('/')
  6. def hello_world():
  7.     return 'Hello, World!'
  8.     
  9. # -------------- new -----------------
  10. from flask_sqlalchemy import SQLAlchemy
  11.  
  12. # 指定資料庫位置
  13. db_uri = 'sqlite:///{}'.format('app.db')
  14. app.config['SQLALCHEMY_DATABASE_URI'] = db_uri
  15. db = SQLAlchemy(app)
  16.  
  17. class User(db.Model):
  18.     id = db.Column(db.Integer, primary_key=True)
  19.     username = db.Column(db.String(80), unique=True, nullable=False)
  20.     email = db.Column(db.String(120), unique=True, nullable=False)
  21.  
  22.     def __repr__(self):
  23.         return '<User %r>' % self.username
  24.  
  25. @app.route('/db_demo')
  26. def db_demo():
  27.     admin = User(username='admin', email='admin@example.com')
  28.     guest = User(username='guest', email='guest@example.com')
  29.     db.session.add(admin)
  30.     db.session.add(guest)
  31.     db.session.commit()
  32.     return User.query.filter_by(username='admin').first().username
  33. # -------------- new -----------------
  1. # manage.py
  2. from flask_script import Manager
  3. from hello import app
  4.  
  5. manager = Manager(app)
  6.  
  7. @manager.command
  8. def hello():
  9.     """Print hello"""
  10.     print("hello")
  11.  
  12. # -------------- new -----------------
  13. from hello import db
  14.  
  15. @manager.command
  16. def initDB():
  17.     """Initializes the database."""
  18.     db.create_all(bind=None)
  19. # -------------- new -----------------
  20.     
  21. if __name__ == "__main__":
  22.     manager.run()
運行方法
# 建立資料庫
python manage.py initDB

# demo 網址為：http://127.0.0.1:5000/db_demo
python manage.py runserver

Flask-Admin
管理資料庫介面 
  1. # hello.py
  2. from flask import Flask
  3. app = Flask(__name__)
  4.  
  5. @app.route('/')
  6. def hello_world():
  7.     return 'Hello, World!'
  8.      
  9. from flask_sqlalchemy import SQLAlchemy
  10.  
  11. # 指定資料庫位置
  12. db_uri = 'sqlite:///{}'.format('app.db')
  13. app.config['SQLALCHEMY_DATABASE_URI'] = db_uri
  14. db = SQLAlchemy(app)
  15.  
  16. class User(db.Model):
  17.     id = db.Column(db.Integer, primary_key=True)
  18.     username = db.Column(db.String(80), nullable=False)
  19.     email = db.Column(db.String(120), nullable=False)
  20.  
  21.     def __repr__(self):
  22.         return '<User %r>' % self.username
  23.         
  24. @app.route('/db_demo')
  25. def db_demo():
  26.     admin = User(username='admin', email='admin@example.com')
  27.     guest = User(username='guest', email='guest@example.com')
  28.     db.session.add(admin)
  29.     db.session.add(guest)
  30.     db.session.commit()
  31.     return User.query.filter_by(username='admin').first().username
  32.     
  33. # -------------- new -----------------
  34. from flask_admin import Admin
  35. from flask_admin.contrib.sqla import ModelView
  36.  
  37. admin = Admin(app, name='microblog', template_mode='bootstrap3')
  38. admin.add_view(ModelView(User, db.session))
  39. # -------------- new -----------------
  1. # manage.py
  2. from flask_script import Manager
  3. from hello import app
  4.  
  5. manager = Manager(app)
  6.  
  7. @manager.command
  8. def hello():
  9.     """Print hello"""
  10.     print("hello")
  11.  
  12. from hello import db
  13.  
  14. @manager.command
  15. def initDB():
  16.     """Initializes the database."""
  17.     db.create_all(bind=None)
  18.     
  19. if __name__ == "__main__":
  20.     manager.run()
運行方法
# 介面網址為：http://127.0.0.1:5000/admin/
python manage.py runserver

Flask-Login
提供使用者登入驗證相關工具 
  1. # hello.py
  2. from flask import Flask
  3. app = Flask(__name__)
  4.  
  5. @app.route('/')
  6. def hello_world():
  7.     return 'Hello, World!'
  8.     
  9. from flask_sqlalchemy import SQLAlchemy
  10.  
  11. # 指定資料庫位置
  12. db_uri = 'sqlite:///{}'.format('app.db')
  13. app.config['SQLALCHEMY_DATABASE_URI'] = db_uri
  14. db = SQLAlchemy(app)
  15.  
  16. class User(db.Model):
  17.     id = db.Column(db.Integer, primary_key=True)
  18.     username = db.Column(db.String(80), nullable=False)
  19.     email = db.Column(db.String(120), nullable=False)
  20.  
  21.     def __repr__(self):
  22.         return '<User %r>' % self.username
  23.          
  24. @app.route('/db_demo')
  25. def db_demo():
  26.     admin = User(username='admin', email='admin@example.com')
  27.     guest = User(username='guest', email='guest@example.com')
  28.     db.session.add(admin)
  29.     db.session.add(guest)
  30.     db.session.commit()
  31.     return User.query.filter_by(username='admin').first().username
  32.      
  33. from flask_admin import Admin
  34. from flask_admin.contrib.sqla import ModelView
  35.  
  36. # -------------- new -----------------
  37. from adminView import MyAdminIndexView, Accounts
  38.  
  39. admin = Admin(app, name='microblog', index_view=MyAdminIndexView(), base_template='backend.html')
  40.  
  41. import flask_login
  42. class BaseModelView(ModelView):    
  43.     def is_accessible(self):
  44.         return flask_login.current_user.is_authenticated
  45.  
  46. admin.add_view(BaseModelView(User, db.session))
  47. admin.add_view(BaseModelView(Accounts, db.session))
  48. # -------------- new -----------------
  1. # manage.py
  2. from flask_script import Manager
  3. from hello import app
  4.  
  5. manager = Manager(app)
  6.  
  7. @manager.command
  8. def hello():
  9.     """Print hello"""
  10.     print("hello")
  11.  
  12. from hello import db
  13.  
  14. @manager.command
  15. def initDB():
  16.     """Initializes the database."""
  17.     db.create_all(bind=None)
  18.     
  19. if __name__ == "__main__":
  20.     manager.run()
新增 adminView.py 
  1. # adminView.py
  2. from flask import url_for, redirect, request
  3. from wtforms import form, fields, validators
  4. from flask_admin import Admin, AdminIndexView, helpers, expose
  5. from flask_login import LoginManager, current_user, login_user, logout_user
  6. from werkzeug.security import generate_password_hash, check_password_hash
  7.  
  8. from hello import db, app
  9.  
  10. # os.urandom(24)
  11. app.config['SECRET_KEY'] = b'\xe1\xa9\x7f9\xa6\x9cwe\xd01\x00\x18\xc2.\xad\x81\xf97Y\xd4wK9P'
  12.  
  13. # Create user model.
  14. class Accounts(db.Model):
  15.     # 若不寫則看 class name
  16.     __tablename__  = 'accounts'
  17.     # 設定 primary_key
  18.     id = db.Column(db.Integer, primary_key=True)
  19.     username = db.Column(db.String(80), unique=True)
  20.     email = db.Column(db.String(120))
  21.     password = db.Column(db.String(64))
  22.  
  23.     # Flask-Login integration
  24.     def is_authenticated(self):
  25.         return True
  26.  
  27.     def is_active(self):
  28.         return True
  29.  
  30.     def is_anonymous(self):
  31.         return False
  32.     
  33.     # for @login_manager.user_loader 使用
  34.     def get_id(self):
  35.         return self.id
  36.  
  37.     def __repr__(self):
  38.         return '<Accounts {}>'.format(self.username)
  39.  
  40. # 登入表格
  41. class LoginForm(form.Form):
  42.     username = fields.TextField(validators=[validators.required()])
  43.     password = fields.PasswordField(validators=[validators.required()])
  44.  
  45.     def validate_username(self, field):
  46.         user = self.get_user()
  47.  
  48.         if user is None:
  49.             raise validators.ValidationError('Invalid user')
  50.  
  51.         # we're comparing the plaintext pw with the the hash from the db
  52.         if not check_password_hash(user.password, self.password.data):
  53.         # to compare plain text passwords use
  54.         # if user.password != self.password.data:
  55.             raise validators.ValidationError('Invalid password')
  56.  
  57.     def get_user(self):
  58.         return db.session.query(Accounts).filter_by(username=self.username.data).first()
  59.  
  60. # 註冊表格
  61. class RegistrationForm(form.Form):
  62.     username = fields.TextField(validators=[validators.required()])
  63.     email = fields.TextField()
  64.     password = fields.PasswordField('New Password', [validators.DataRequired(),
  65.                                                      validators.EqualTo('confirm', message='Passwords must match')
  66.                                                     ])
  67.     confirm = fields.PasswordField('Repeat Password')
  68.     
  69.     def validate_username(self, field):
  70.         if db.session.query(Accounts).filter_by(username=self.username.data).count() > 0:
  71.             raise validators.ValidationError('Duplicate username')
  72.  
  73. # 初始登入
  74. def init_login():
  75.     login_manager = LoginManager()
  76.     login_manager.init_app(app)
  77.  
  78.     # Create user loader function
  79.     @login_manager.user_loader
  80.     def load_user(user_id):
  81.         return db.session.query(Accounts).get(user_id)
  82.  
  83. # 建立 admin 的登入介面
  84. class MyAdminIndexView(AdminIndexView):
  85.     @expose('/')
  86.     def index(self):
  87.         if not current_user.is_authenticated:
  88.             return redirect(url_for('.login_view'))
  89.         return super(MyAdminIndexView, self).index()
  90.  
  91.     @expose('/login/', methods=('GET', 'POST'))
  92.     def login_view(self):
  93.         # handle user login
  94.         form = LoginForm(request.form)
  95.         if helpers.validate_form_on_submit(form):
  96.             user = form.get_user()
  97.             login_user(user)
  98.  
  99.         if current_user.is_authenticated:
  100.             return redirect(url_for('.index'))
  101.         link = '<p>Don\'t have an account? <a href="' + url_for('.register_view') + '">Click here to register.</a></p>'
  102.         self._template_args['form'] = form
  103.         self._template_args['link'] = link
  104.         return super(MyAdminIndexView, self).index()
  105.  
  106.     @expose('/register/', methods=('GET', 'POST'))
  107.     def register_view(self):
  108.         form = RegistrationForm(request.form)
  109.         if helpers.validate_form_on_submit(form):
  110.             user = Accounts()
  111.  
  112.             form.populate_obj(user)
  113.             # we hash the users password to avoid saving it as plaintext in the db,
  114.             # remove to use plain text:
  115.             user.password = generate_password_hash(form.password.data)
  116.  
  117.             db.session.add(user)
  118.             db.session.commit()
  119.  
  120.             login_user(user)
  121.             return redirect(url_for('.index'))
  122.         link = '<p>Already have an account? <a href="' + url_for('.login_view') + '">Click here to log in.</a></p>'
  123.         self._template_args['form'] = form
  124.         self._template_args['link'] = link
  125.         return super(MyAdminIndexView, self).index()
  126.  
  127.     @expose('/logout/')
  128.     def logout_view(self):
  129.         logout_user()
  130.         return redirect(url_for('.index'))
  131.  
  132. # Initialize flask-login
  133. init_login()
新增 backend.html
  1. {% extends 'admin/base.html' %}
  2.  
  3. {% block access_control %}
  4. {% if current_user.is_authenticated %}
  5. <div class="btn-group pull-right">
  6.     <a class="btn dropdown-toggle" data-toggle="dropdown" href="#">
  7.         <i class="icon-user"></i> {{ current_user.login }} <span class="caret"></span>
  8.     </a>
  9.     <ul class="dropdown-menu">
  10.         <li><a href="{{ url_for('admin.logout_view') }}">Log out</a></li>
  11.     </ul>
  12. </div>
  13. {% endif %}
  14. {% endblock %}
新增 admin/index.html
  1. {% extends 'admin/master.html' %}
  2. {% block body %}
  3. {{ super() }}
  4. <div class="row-fluid">
  5.  
  6.     <div>
  7.         {% if current_user.is_authenticated %}
  8.         <p class="lead">
  9.             Authentication
  10.         </p>
  11.         <p>
  12.             {{ current_user }} Example
  13.         </p>
  14.         {% else %}
  15.         <form method="POST" action="">
  16.             {{ form.hidden_tag() if form.hidden_tag }}
  17.             {% for f in form if f.type != 'CSRFTokenField' %}
  18.             <div>
  19.             {{ f.label }}
  20.             {{ f }}
  21.             {% if f.errors %}
  22.             <ul>
  23.                 {% for e in f.errors %}
  24.                 <li>{{ e }}</li>
  25.                 {% endfor %}
  26.             </ul>
  27.             {% endif %}
  28.             </div>
  29.             {% endfor %}
  30.             <button class="btn" type="submit">Submit</button>
  31.         </form>
  32.         {{ link | safe }}
  33.         {% endif %}
  34.     </div>
  35.  
  36.     <a class="btn btn-primary" href="/"><i class="icon-arrow-left icon-white"></i> Back</a>
  37. </div>
  38. {% endblock body %}
運行方法
# 介面網址為：http://127.0.0.1:5000/admin/
python manage.py runserver

Flask Blueprints
將 view 額外拆成另一個檔案 view.py，以便管理 
  1. # hello.py
  2. from flask import Flask
  3. from view import simple_page
  4. app = Flask(__name__)
  5.  
  6. app.register_blueprint(simple_page)
  1. # manage.py
  2. from flask_script import Manager
  3. from hello import app
  4.  
  5. manager = Manager(app)
  6.     
  7. if __name__ == "__main__":
  8.     manager.run()
  1. # view.py
  2. from flask import Blueprint
  3.  
  4. simple_page = Blueprint('simple_page', __name__,
  5.                         template_folder='templates')
  6.  
  7. @simple_page.route('/')
  8. def hello_world():
  9.     return 'Hello, World!'

參考

用 Flask 與 SQLite 架抽籤網站

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