form的valid验证的原理

form的valid验证的原理

import re
import copy


class ValidateError(Exception):
    def __init__(self,detail):
        self.detail = detail



# ###################### 插件
class TextInput(object):
    def __str__(self):
        return "<input type='text' />"

class EmailInput(object):
    def __str__(self):
        return "<input type='email' />"




# ###################### 内部包含正则，用于验证
class Field(object):
    def __init__(self,required=True,error_messages=None,widget=None):
        self.required = required
        self.error_messages = error_messages
        if not widget:
            self.widget = TextInput()
        else:
            self.widget = widget
    def __str__(self):
        return str(self.widget)

class CharField(Field):

    def valid(self,val):
        if self.required:
            if not val:
                msg = self.error_messages['required']
                raise ValidateError(msg)
        return val


class EmailField(Field):
    REG = "^w+@w+$"

    def valid(self,val):
        if self.required:
            if not val:
                msg = self.error_messages['required']
                raise ValidateError(msg)
        result = re.match(self.REG,val)
        if not result:
            msg = self.error_messages.get('invalid','格式错误')
            raise ValidateError(msg)
        return val





# ###################### Form，获取用户提交内容+获取定义的字段对象
class Form(object):

    def __init__(self,data=None):
        # 获取派生类中的所有静态字段
        # print(self.__class__.__dict__)
        self.data = data
        self.fields = copy.deepcopy(self.__class__.declare_field)
        self.cleaned_data = {}
        self.errors = {}

    def __new__(cls, *args, **kwargs):
        declare_field = {}
        for field_name, field in cls.__dict__.items():
            if isinstance(field,Field):
                declare_field[field_name] = field
        cls.declare_field = declare_field
        return object.__new__(cls)

    def is_valid(self):
        # 用户提交的数据
        # self.data # {"username":"alex","pwd":18,'xxx':11}
        # self.fields # {"username":CharField(), "pwd": EmailField() }
        for field_name,filed in self.fields.items():
            try:
                input_val = self.data.get(field_name)
                val = filed.valid(input_val)
                method = getattr(self,"cleaned_%s" %field_name,None)
                if method:
                    val = method(val)
                self.cleaned_data[field_name] = val
            except ValidateError as e:
                self.errors[field_name] = e.detail

        return len(self.errors) == 0

    def __iter__(self):

        return iter(self.fields.values())

class UserForm(Form):
    username = CharField(error_messages={'required':'用户名不能为空'},widget=TextInput())
    pwd = EmailField(error_messages={'required':'密码不能为空','invalid':'密码格式错误'},widget=EmailInput())



# ############### 应用
obj = UserForm(data={"username":"sdf","pwd":"sdf",'xxx':666})
if obj.is_valid():
    print('验证成功',obj.cleaned_data)
else:
    print("验证失败",obj.errors)


# ##################### HTML #####################
for x in obj:
    print(x)