完成登录功能，用session记住用户名

from flask import Flask, render_template,request,redirect,url_for,session
from flask_sqlalchemy import SQLAlchemy
import config
from functools import wraps
from datetime import datetime

app = Flask(__name__)
app.config.from_object(config)
db = SQLAlchemy(app)

class User(db.Model):
    __tablename__ = 'user'
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    username = db.Column(db.String(20), nullable=False)
    password = db.Column(db.String(20), nullable=False)
    nickname=db.Column(db.String(20))



#db.creat_all()

'''
#修改密码
user=User.query.filter(User.username=='mis114').first()
user.password='234567'
print(user.username,user.password)

#删除
user=User.query.filter(User.username=='mis114').first()
db.session.delete(user)
db.session.commit()

#创建用户
user=User(username='mis114',password='mis1114')
db.session.add(user)
db.session.commit()

user=User.query.filter(User.username=='mis1114').first()
print(user.username,user.password)


'''

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/regist/', methods=['GET', 'POST'])
def regist():
    if request.method=='GET':
        return render_template('regist.html')
    else:
        # 获取form中的数据，判断用户名是否存在，存到数据库中
        username=request.form.get('username')
        nickname = request.form.get('nickname')
        password=request.form.get('password')
        user=User.query.filter(User.username==username).first()
        # 重定向到登录页
        if user:
            return u'用户名已存在'
        else:
            user=User(username=username,nickname=nickname,password=password)
            db.session.add(user)
            db.session.commit()
            return redirect(url_for('login'))


@app.route('/login/',methods=['GET','POST'])
def login():
    if request.method == 'GET':
        return render_template('login.html')
    else:
        # 获取form中的数据，判断用户名是否存在，存到数据库中
        username = request.form.get('username')
        password = request.form.get('password')
        user = User.query.filter(User.username == username).first()
        # 重定向到登录页
        #nickname = request.form.get('nickname')

        if user:
            session['user']=username
            session.permanent=True
            return redirect(url_for('index'))
        else:
            return u'error username or password'


            # if user:
            #     return 'username existed'
            # else:
            #     user=User(username=username,password=password)
            #     db.session.add(user)
            #     db.session.commit()


@app.route('/question/')
def question():
    return render_template('question.html')


if __name__ == '__main__':
    app.run(debug=True)

　　

import os

SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://root:@localhost:3306/test?charset=utf8'
SQLALCHEMY_TRACK_MODIFICATIONS = False

SECRET_KEY=os.urandom(24)

DIALECT='mysql'
DRIVER='mysqldb'
USERNAME='root'
PASSWORD='ROOT'
HOST='127.0.0.1'
PORT='3306'
DATABASE='mis_db'