request_started = _signals.signal(‘request-started‘) # 请求到来前执行 request_finished = _signals.signal(‘request-finished‘) # 请求结束后执行 before_render_template = _signals.signal(‘before-render-template‘) # 模板渲染前执行 template_rendered = _signals.signal(‘template-rendered‘) # 模板渲染后执行 got_request_exception = _signals.signal(‘got-request-exception‘) # 请求执行出现异常时执行 request_tearing_down = _signals.signal(‘request-tearing-down‘) # 请求执行完毕后自动执行（无论成功与否） appcontext_tearing_down = _signals.signal(‘appcontext-tearing-down‘)# 请求上下文执行完毕后自动执行（无论成功与否） appcontext_pushed = _signals.signal(‘appcontext-pushed‘) # 请求上下文push时执行 appcontext_popped = _signals.signal(‘appcontext-popped‘) # 请求上下文pop时执行 message_flashed = _signals.signal(‘message-flashed‘) # 调用flask在其中添加数据时，自动触发
Flask框架中的信号基于blinker，其主要就是让开发者可是在flask请求过程中定制一些用户行为。首先要安装blinker
pip install blinker
from flask import Flask,signals app = Flask(__name__) app.debug = True app.secret_key = ‘abcdef‘ def func(*args,**kwargs): print(‘触发信号‘,args,kwargs) signals.request_started.connect(func) @app.route(‘/‘) def index(): print(‘hello‘) return ‘hello world‘ if __name__ == ‘__main__‘: app.run()
运行结果：
WTForms是一个支持多个web框架的form组件，主要用于对用户请求数据进行验证。安装方法
pip install wtforms
用户登录时，对用户名和密码进行验证
（1）app.py
from flask import Flask, render_template, request, redirect from wtforms import Form from wtforms.fields import simple from wtforms import validators from wtforms import widgets app = Flask(__name__, template_folder=‘templates‘) app.debug = True class LoginForm(Form): name = simple.StringField( label=‘用户名‘, #自定义的验证规则 validators=[ validators.DataRequired(message=‘用户名不能为空.‘), validators.Length(min=6, max=18, message=‘用户名长度必须大于%(min)d且小于%(max)d‘) ], #页面显示的插件 widget=widgets.TextInput(), #加属性 render_kw={‘class‘: ‘form-control‘} ) pwd = simple.PasswordField( label=‘密码‘, validators=[ validators.DataRequired(message=‘密码不能为空.‘), validators.Length(min=8, message=‘用户名长度必须大于%(min)d‘), #正则表达式 validators.Regexp(regex="^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[A-Za-z\d$@$!%*?&]{8,}", message=‘密码至少8个字符，至少1个大写字母，1个小写字母，1个数字和1个特殊字符‘) ], widget=widgets.PasswordInput(), render_kw={‘class‘: ‘form-control‘} ) @app.route(‘/login‘, methods=[‘GET‘, ‘POST‘]) def login(): if request.method == ‘GET‘: form = LoginForm() return render_template(‘login.html‘, form=form) else: form = LoginForm(formdata=request.form) if form.validate(): print(‘用户提交数据通过格式验证，提交的值为：‘, form.data) else: print(form.errors) return render_template(‘login.html‘, form=form) if __name__ == ‘__main__‘: app.run()
（2）login.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <h1>登录</h1> <form method="post"> <p>{{form.name.label}} {{form.name}} {{form.name.errors[0] }}</p> <p>{{form.pwd.label}} {{form.pwd}} {{form.pwd.errors[0] }}</p> <input type="submit" value="提交"> </form> </body> </html>
用户名和密码格式不对
（1）app.py
from flask import Flask, render_template, request, redirect from wtforms import Form from wtforms.fields import core from wtforms.fields import html5 from wtforms.fields import simple from wtforms import validators from wtforms import widgets app = Flask(__name__, template_folder=‘templates‘) app.debug = True class RegisterForm(Form): name = simple.StringField( label=‘用户名‘, validators=[ validators.DataRequired() ], widget=widgets.TextInput(), render_kw={‘class‘: ‘form-control‘}, default=‘derek‘ ) pwd = simple.PasswordField( label=‘密码‘, validators=[ validators.DataRequired(message=‘密码不能为空.‘) ], widget=widgets.PasswordInput(), render_kw={‘class‘: ‘form-control‘} ) pwd_confirm = simple.PasswordField( label=‘重复密码‘, validators=[ validators.DataRequired(message=‘重复密码不能为空.‘), #EqualTo：要跟那个字段一样 validators.EqualTo(‘pwd‘, message="两次密码输入不一致") ], widget=widgets.PasswordInput(), render_kw={‘class‘: ‘form-control‘} ) email = html5.EmailField( label=‘邮箱‘, validators=[ validators.DataRequired(message=‘邮箱不能为空.‘), validators.Email(message=‘邮箱格式错误‘) ], widget=widgets.TextInput(input_type=‘email‘), render_kw={‘class‘: ‘form-control‘} ) #RadiField单选 gender = core.RadioField( label=‘性别‘, choices=( (1, ‘男‘), (2, ‘女‘), ), coerce=int #因为前段提交过来的数据都是str格式，比如“1”，“2”，这里转换成int ) #单选的下拉框 city = core.SelectField( label=‘城市‘, choices=( (‘bj‘, ‘北京‘), (‘sh‘, ‘上海‘), ) ) #多选的下拉框 hobby = core.SelectMultipleField( label=‘爱好‘, choices=( (1, ‘篮球‘), (2, ‘足球‘), ), coerce=int ) favor = core.SelectMultipleField( label=‘喜好‘, choices=( (1, ‘篮球‘), (2, ‘足球‘), ), widget=widgets.ListWidget(prefix_label=False), option_widget=widgets.CheckboxInput(), #多选 coerce=int, default=[1, 2] ) def __init__(self, *args, **kwargs): super(RegisterForm, self).__init__(*args, **kwargs) #重写默认的方法 self.favor.choices = ((1, ‘篮球‘), (2, ‘足球‘), (3, ‘羽毛球‘)) #钩子函数 def validate_pwd_confirm(self, field): """ 自定义pwd_confirm字段规则，例：与pwd字段是否一致 :param field: :return: """ # 最开始初始化时，self.data中已经有所有的值 if field.data != self.data[‘pwd‘]: # raise validators.ValidationError("密码不一致") # 继续后续验证 raise validators.StopValidation("密码不一致") # 不再继续后续验证 @app.route(‘/register‘, methods=[‘GET‘, ‘POST‘]) def register(): if request.method == ‘GET‘: #data={‘gender‘: 1 } 传到前端页面显示的默认值，这里只设置了gender，其它字段也可以通过这种方式设置 form = RegisterForm(data={‘gender‘: 1}) return render_template(‘register.html‘, form=form) else: form = RegisterForm(formdata=request.form) if form.validate(): print(‘用户提交数据通过格式验证，提交的值为：‘, form.data) else: print(form.errors) return render_template(‘register.html‘, form=form) if __name__ == ‘__main__‘: app.run()
(2).register.html
可以直接循环取出所有字段
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <h1>用户注册</h1> <form method="post" novalidate style="padding:0 50px"> {% for item in form %} <p>{{item.label}}: {{item}} {{item.errors[0] }}</p> {% endfor %} <input type="submit" value="提交"> </form> </body> </html>
注册页面显示：
原文：https://www.cnblogs.com/derek1184405959/p/9031618.html