from flask import Flask,request,render_templatefrom wtforms import Form,StringFieldfrom wtforms import validatorsfrom wtforms.validators import Length,EqualToclass RegisterForm(Form):    username = StringField(validators=[Length(max=10,min=3,message='用户名长度不正确')])    password = StringField(validators=[Length(max=10,min=3,message='密码长度不正确')])    password_repeat = StringField(validators=[Length(max=10,min=3,message='密码长度不正确'),EqualTo('password')])app = Flask(__name__)@app.route('/')def hello_world():    return 'Hello World!'@app.route('/register/',methods=['get','post'])def register():    if request.method == 'GET':        return render_template('register.html')    else:        # username = request.form.get('username')        # password = request.form.get('password')        # password_repeat = request.form.get('password_repeat')        # if 3 > len(username) or len(username)> 10:        #     return '用户名长度不正确'        # if 3 > len(password) or len(password)> 10:        #     return '密码长度不正确'        # if password != password_repeat:        #     return '密码输入不一致'        form = RegisterForm(request.form)        if form.validate():            return 'success'        else:            print(form.errors)#{'username': ['用户名长度不正确'],            # 'password': ['密码长度不正确'], 'password_repeat': ['密码长度不正确']}            #因为是字典，获取方式我就不写了            return 'fail'if __name__ == '__main__':    app.run(debug=True)