1. js文件： onclick函数return True时才提交表单，return False时不提交表单。
2. html文件：
   1. <form>中设置 action和method="post"
   2. <input> 中设置 name
3. 主py文件中：
   1. from flask import  request, redirect, url_for
   2. @app.route('/regist/', methods=['GET', 'POST’])

def regist():

   if request.method == 'GET':

        return render_template('regist.html')

   else:

        username = request.form.get(‘username’)#获取form中的数据

        判断用户名是否存在

        存到数据库中

        redirect重定向到登录页

1 from flask import Flask,render_template,request,redirect,url_for,session 2 from flask_sqlalchemy import SQLAlchemy 3 import config 4  5 app = Flask(__name__) 6 app.config.from_object(config) 7 db = SQLAlchemy(app) 8  9 class User(db.Model):10     __tablename__ = 'user'11     id = db.Column(db.Integer,primary_key=True,autoincrement=True)12     username = db.Column(db.String(20),nullable=False)13     password = db.Column(db.String(20),nullable=False)14     nickname = db.Column(db.String(50))15 16 # user = User(username = 'misjiaojiao',password = 'misjiaojiao')17 # db.session.add(user)18 # db.session.commit()19 20 # user = User.query.filter(User.username == 'misjiaojiao').first()21 # db.session.delete(user)22 # db.session.commit()23 24 # user = User.query.filter(User.username == 'misjiaojiao').first()25 # user.password='1234657'26 # db.session.commit()27 28 db.create_all()29 30 @app.route('/')31 def index():32     return render_template('switch切换.html')33 34 @app.route('/login/', methods = ['GET','POST'])35 def login():36     return render_template('login登录.html')37 38 @app.route('/regist/', methods = ['GET','POST'])39 def regist():40     if request.method == 'GET':41         return render_template('regist注册.html')42     else:43         username = request.form.get('username')44         password = request.form.get('password')45         nickname = request.form.get('nickname')46         user = User.query.filter(User.username == username).first()47         if user:48             return 'username existed'49         else:50             user = User(username = username,password = password,nickname = nickname)51             db.session.add(user)  # 数据库操作52             db.session.commit()53             return redirect(url_for('login'))54 55 56 57 58 if __name__ == '__main__':59     app.run(debug=True)