本文實例講述了Flask框架Flask-Principal基本用法。分享給大家供大家參考，具體如下：

Flask-Principal是Flask框架的一個擴展，主要主件是Identity，Needs，Permission和IdentityContext。

安裝

pip install flask-principal

初始化

from flask_principal import Principalprincipal = Principal()principal.init_app(app)

權限管理

permissions.py

from flask-principal import Permission,RoleNeedfrom functools import wraps# 定義相關角色NORMAL = "NORMAL"ADMIN = "ADMIN"ROLES = (  ("NORMAL","普通用戶"),  ("ADMIN","管理員"))admin_permission = Permission(RoleNeed(ADMIN))def admin_authority(func):  @wraps  def decorated_view(*args,**kwargs):    if admin_permission.can():      return func(*args,**kwargs)    else:      return "非Admin用戶"  return decorated_view

添加Role Model

userinfo.py

from app import login_managerfrom app.db import Base,engine,sessionfrom sqlalchemy import Column,String,Integer,create_enginefrom sqlalchemy_utils.types.choice import ChoiceTypefrom flask_login import UserMixinfrom permissions import ADMIN,ROLESclass User(Base,UserMixin):  __tablename__ = "user"  id = Column(Integer,primary_key=True)  user = Column(String(16))  password = Column(String(16))  roles = Column(ChoiceType(ROLES),default=ADMIN)@login_manager.user_loadeddef user_loaded(id):  return session.query(User).filter_by(id=id).first()Base.metadata.create_all(engine)

使用user_loader裝飾器的回調函數非常重要，它將決定user對象是否在登錄狀態。試想只有Admin權限操作的事情，那么此用戶是必需先登錄，否則無法驗證Admin權限。更多Flask-Login相關操作可參考《Flask框架Flask-Login用法》

登錄

驗證用戶與密碼等是否正確，后執行Flask-Login登錄操作，記錄登錄狀態，驗證用戶權限

from app import appfrom flask import requestfrom flask_login import login_userfrom flask_principal import current_app,identity_changed,Identityfrom userinfo import Userfrom app.db import session@app.route("/login",methods=["POST"])def login():  user = request.form.get("user",None)  password = request.form.get("password",None)  if not user or not password:    ...  user = session.query(User).filter_by(user=user,password=password).first()  if not user:    ...  # 登錄  login_user(user)  # 發送信號，載入用戶權限  identity_changed.send(current_app._get_current_object(),identity=Identity(user.id))  return ...