一、wtforms源码流程
1、实例化流程分析
# 源码流程
1. 执行type的 __call__ 方法，读取字段到静态字段 cls._unbound_fields 中； meta类读取到cls._wtforms_meta中
2. 执行构造方法
a. 循环cls._unbound_fields中的字段，并执行字段的bind方法，然后将返回值添加到 self._fields[name] 中。
即：
_fields = {
name: wtforms.fields.core.StringField(),
}
PS：由于字段中的__new__方法，实例化时：name = simple.StringField(label=‘用户名‘)，创建的是UnboundField(cls, *args, **kwargs)，当执行完bind之后，才变成执行 wtforms.fields.core.StringField()
b. 循环_fields，为对象设置属性
for name, field in iteritems(self._fields):
# Set all the fields to attributes so that they obscure the class
# attributes with the same names.
setattr(self, name, field)
c. 执行process，为字段设置默认值：self.process(formdata, obj, data=data, **kwargs)
优先级：obj,data,formdata;
再循环执行每个字段的process方法，为每个字段设置值：
for name, field, in iteritems(self._fields):
if obj is not None and hasattr(obj, name):
field.process(formdata, getattr(obj, name))
elif name in kwargs:
field.process(formdata, kwargs[name])
else:
field.process(formdata)
执行每个字段的process方法，为字段的data和字段的raw_data赋值
def process(self, formdata, data=unset_value):
self.process_errors = []
if data is unset_value:
try:
data = self.default()
except TypeError:
data = self.default
self.object_data = data
try:
self.process_data(data)
except ValueError as e:
self.process_errors.append(e.args[0])
if formdata:
try:
if self.name in formdata:
self.raw_data = formdata.getlist(self.name)
else:
self.raw_data = []
self.process_formdata(self.raw_data)
except ValueError as e:
self.process_errors.append(e.args[0])
try:
for filter in self.filters:
self.data = filter(self.data)
except ValueError as e:
self.process_errors.append(e.args[0])
d. 页面上执行print(form.name) 时，打印标签
因为执行了：
字段的 __str__ 方法
字符的 __call__ 方法
self.meta.render_field(self, kwargs)
def render_field(self, field, render_kw):
other_kw = getattr(field, ‘render_kw‘, None)
if other_kw is not None:
render_kw = dict(other_kw, **render_kw)
return field.widget(field, **render_kw)
执行字段的插件对象的 __call__ 方法，返回标签字符串
2、验证流程分析
a. 执行form的validate方法，获取钩子方法
def validate(self):
extra = {}
for name in self._fields:
inline = getattr(self.__class__, ‘validate_%s‘ % name, None)
if inline is not None:
extra[name] = [inline]
return super(Form, self).validate(extra)
b. 循环每一个字段，执行字段的 validate 方法进行校验(参数传递了钩子函数)
def validate(self, extra_validators=None):
self._errors = None
success = True
for name, field in iteritems(self._fields):
if extra_validators is not None and name in extra_validators:
extra = extra_validators[name]
else:
extra = tuple()
if not field.validate(self, extra):
success = False
return success
c. 每个字段进行验证时候
字段的pre_validate 【预留的扩展】
字段的_run_validation_chain，对正则和字段的钩子函数进行校验
字段的post_validate【预留的扩展】
二、自定义Form组件
#!usr/bin/env python
# -*- coding:utf-8 -*-
from flask import Flask,render_template,request,Markup
app = Flask(__name__,template_folder="templates")
app.debug = True
# ==============通过这几个类就可以显示了-==============
#插件
class Widget(object):
pass
class InputText(Widget):
def __call__(self, *args, **kwargs):
return "<input type=‘text‘ name=‘name‘>"
class TextArea(Widget):
def __call__(self, *args, **kwargs):
return Markup("<textarea name=‘email‘></textarea>")
#Form
class BaseForm(object):
def __init__(self):
#获取当前所有的字段
_fields = {}
for name, field in self.__class__.__dict__.items():
if isinstance(field, Field): # 筛选出字段是name和emailDe
_fields[name] = field
self._fields = _fields
self.data = {}
# print(_fields) # {‘name‘: 111, ‘email‘: 222}
def validate(self,request_data):
#先找到所有的字段，在执行每一个字段的validate方法
flag = True
for name, field in self._fields.items():
input_val = request_data.get(name,"") #用户输入的值
result= field.validate(input_val) #每一个字段自己校验
print("???????????",input_val,result)
if not result:
flag = False
else:
self.data[name] = input_val
return flag
#字段
class Field(object):
‘‘‘所有类的基类‘‘‘
def __str__(self): #python中的静态字段通过类能找到，通过对象也能找到
return Markup(self.widget()) #self就是StringField，self
class StringField(Field): #每个字段打印的时候都要去执行__str__，所以选择放在基类里面，自己没有就调用父类的
widget = InputText()
def validate(self,val):
if val:
return True
class EmaliField(Field):
widget = TextArea()
reg = ".*@.*"
def validate(self,val):
import re
print(re.match(self.reg,val),"************")
if re.match(self.reg,val):
return True
# ===============使用===============
class LoginForm(BaseForm):
name = StringField()
email = EmaliField()
@app.route(‘/index‘, methods=["GET","POST"])
def index():
form = LoginForm()
ret = form.validate(request.form)
print("验证成功",ret)
print("验证成功的值",form.data)
# print(form.name)
# print(form.email)
return render_template("index.html",form=form)
if __name__ == ‘__main__‘:
app.run()
