本文实例讲述了Flask框架Flask-Principal基本用法。分享给大家供大家参考，具体如下：
Flask-Principal是Flask框架的一个扩展，主要主件是Identity，Needs，Permission和IdentityContext。
- Identity：代表用户，从各个位置存储和加载每个请求，包含用户拥有的访问权限。
- Needs：需求是访问控制的最小粒度，代表了这种情况的具体参数。例如：管理用户、可以编辑帖子.
- Permission：权限
- IdentityContext：针对某个权限特定的上下文，可用作上下文管理器或装饰器
安装
pip install flask-principal
初始化
from flask_principal import Principal principal = Principal() principal.init_app(app)
权限管理
permissions.py
from flask-principal import Permission,RoleNeed
from functools import wraps
# 定义相关角色
NORMAL = "NORMAL"
ADMIN = "ADMIN"
ROLES = (
("NORMAL","普通用户"),
("ADMIN","管理员")
)
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用户"
return decorated_view
添加Role Model
userinfo.py
from app import login_manager from app.db import Base,engine,session from sqlalchemy import Column,String,Integer,create_engine from sqlalchemy_utils.types.choice import ChoiceType from flask_login import UserMixin from permissions import ADMIN,ROLES class 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_loaded def user_loaded(id): return session.query(User).filter_by(id=id).first() Base.metadata.create_all(engine)
使用user_loader装饰器的回调函数非常重要，它将决定user对象是否在登录状态。试想只有Admin权限操作的事情，那么此用户是必需先登录，否则无法验证Admin权限。更多Flask-Login相关操作可参考《Flask框架Flask-Login用法》
登录
验证用户与密码等是否正确，后执行Flask-Login登录操作，记录登录状态，验证用户权限
from app import app
from flask import request
from flask_login import login_user
from flask_principal import current_app,identity_changed,Identity
from userinfo import User
from 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:
...
# 登录
login_user(user)
# 发送信号，载入用户权限
identity_changed.send(current_app._get_current_object(),identity=Identity(user.id))
return ...
identity_changed.send()函数会将sender:current_app._get_current_object()当前应用app和身份对象和identity:Identity(user.id)用户对象以信号的新式发送出去，开发者可以用identity_loaded.connect_via(app)接收信号，并载入权限
from flask_login import current_user
from flask_principal import identity_loaded,UserNeed,RoleNeed
@identity_loaded.connect_via(app)
def on_identity_loaded(sendder,identity):
identity.user = current_user
if hasattr(current_user,"id"):
identity.provides.add(UserNeed(current_user.id))
if hasattr(current_user,"roles"):
identity.provides.add(RoleNeed(current_user.roles.code))
实现只有Admin权限用户才能操作删除用户
from app import app
from permission import admin_authority
@app.route("/delete_user",methods=["POST"])
@admin_authority
def delete_user():
...
希望本文所述对大家基于Flask框架的Python程序设计有所帮助。
