wtforms源码流程

实例化流程分析

 1 # 源码流程
 2     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
 3     2. 执行构造方法
 4         
 5         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。
 6             即：
 7                 _fields = {
 8                     name: wtforms.fields.core.StringField(),
 9                 }
10                 
11             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()
12         
13         b. 循环_fields，为对象设置属性
14             for name, field in iteritems(self._fields):
15                 # Set all the fields to attributes so that they obscure the class
16                 # attributes with the same names.
17                 setattr(self, name, field)
18         c. 执行process，为字段设置默认值：self.process(formdata, obj, data=data, **kwargs)
19             优先级：obj,data,formdata;
20             
21             再循环执行每个字段的process方法，为每个字段设置值：
22             for name, field, in iteritems(self._fields):
23                 if obj is not None and hasattr(obj, name):
24                     field.process(formdata, getattr(obj, name))
25                 elif name in kwargs:
26                     field.process(formdata, kwargs[name])
27                 else:
28                     field.process(formdata)
29             
30             执行每个字段的process方法，为字段的data和字段的raw_data赋值
31             def process(self, formdata, data=unset_value):
32                 self.process_errors = []
33                 if data is unset_value:
34                     try:
35                         data = self.default()
36                     except TypeError:
37                         data = self.default
38         
39                 self.object_data = data
40         
41                 try:
42                     self.process_data(data)
43                 except ValueError as e:
44                     self.process_errors.append(e.args[0])
45         
46                 if formdata:
47                     try:
48                         if self.name in formdata:
49                             self.raw_data = formdata.getlist(self.name)
50                         else:
51                             self.raw_data = []
52                         self.process_formdata(self.raw_data)
53                     except ValueError as e:
54                         self.process_errors.append(e.args[0])
55         
56                 try:
57                     for filter in self.filters:
58                         self.data = filter(self.data)
59                 except ValueError as e:
60                     self.process_errors.append(e.args[0])
61                 
62         d. 页面上执行print(form.name) 时，打印标签
63             
64             因为执行了：
65                 字段的 __str__ 方法
66                 字符的 __call__ 方法
67                 self.meta.render_field(self, kwargs)
68                     def render_field(self, field, render_kw):
69                         other_kw = getattr(field, 'render_kw', None)
70                         if other_kw is not None:
71                             render_kw = dict(other_kw, **render_kw)
72                         return field.widget(field, **render_kw)
73                 执行字段的插件对象的 __call__ 方法，返回标签字符串

View Code

验证流程分析

 1 a. 执行form的validate方法，获取钩子方法
 2             def validate(self):
 3                 extra = {}
 4                 for name in self._fields:
 5                     inline = getattr(self.__class__, 'validate_%s' % name, None)
 6                     if inline is not None:
 7                         extra[name] = [inline]
 8         
 9                 return super(Form, self).validate(extra)
10         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)
11             def validate(self, extra_validators=None):
12                 self._errors = None
13                 success = True
14                 for name, field in iteritems(self._fields):
15                     if extra_validators is not None and name in extra_validators:
16                         extra = extra_validators[name]
17                     else:
18                         extra = tuple()
19                     if not field.validate(self, extra):
20                         success = False
21                 return success
22         c. 每个字段进行验证时候
23             字段的pre_validate 【预留的扩展】
24             字段的_run_validation_chain，对正则和字段的钩子函数进行校验
25             字段的post_validate【预留的扩展】

View Code

回到顶部

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()