DRF源码-fields.py

概述https://www.cnblogs.com/pyspark/p/8607801.html https://www.cnblogs.com/LYliangying/articles/9896548.html   fieids.py主要定义了各种字段的序列化类。Field是基类。 class Field _creation_counter = 0 default_error_

https://www.cnblogs.com/pyspark/p/8607801.html

https://www.cnblogs.com/LYliangying/articles/9896548.html

 

fIEIDs.py主要定义了各种字段的序列化类。FIEld是基类。

class FIEld

    _creation_counter = 0    default_error_messages = {        ‘required‘: _(‘This fIEld is required.‘),‘null‘: _(‘This fIEld may not be null.‘)    }    default_valIDators = []     #默认验证器初始化为空List    default_empty_HTML = empty    initial = None

　　

    # 在构造函数中，给出了各种定义参数，由子类继承，在实例化时传参，来控制这个字段的各种属性    # read_only，表明只用于序列化输出    # write_only， 表明只用于反序列化输入，比如密码    # required， 表明在反序列化时必须输入    # default， 反序列化时使用的默认值    # initial    # source，    # label， 用于HTML展示API页面时，显示的字段名称    # help_text， 用于HTML展示API页面时，显示的字段帮助提示信息    # style    # error_messages， 包含错误编号与错误信息的字典    # valIDators， 该字段使用的验证器    # allow_null,表明该字段是否允许传入None，默认False    def __init__(self,read_only=False,write_only=False,required=None,default=empty,initial=empty,source=None,label=None,help_text=None,style=None,error_messages=None,valIDators=None,allow_null=False):        self._creation_counter = FIEld._creation_counter        FIEld._creation_counter += 1        # If `required` is unset,then use `True` unless a default is provIDed.        if required is None:            required = default is empty and not read_only        # Some combinations of keyword arguments do not make sense.        # 断言一些没有意义的参数组合        assert not (read_only and write_only),NOT_READ_ONLY_WRITE_ONLY        assert not (read_only and required),NOT_READ_ONLY_required        assert not (required and default is not empty),NOT_required_DEFAulT        assert not (read_only and self.__class__ == FIEld),USE_ReadonlyFIELD        # 将传入的参数赋值给实例（属性初始化）        self.read_only = read_only        self.write_only = write_only        self.required = required        self.default = default        self.source = source        self.initial = self.initial if (initial is empty) else initial        self.label = label        self.help_text = help_text        self.style = {} if style is None else style        self.allow_null = allow_null        if self.default_empty_HTML is not empty:            if default is not empty:                self.default_empty_HTML = default        if valIDators is not None:            self.valIDators = List(valIDators)        # These are set up by `.bind()` when the fIEld is added to a serializer.        self.fIEld_name = None        self.parent = None        # Collect default error message from self and parent classes        messages = {}        for cls in reversed(self.__class__.__mro__):            messages.update(getattr(cls,‘default_error_messages‘,{}))        messages.update(error_messages or {})        self.error_messages = messages

　　

    # .valIDators is a lazily loaded property,that gets its default    # value from `get_valIDators`.    # valIDators属性设置    @property    def valIDators(self):        if not hasattr(self,‘_valIDators‘):            self._valIDators = self.get_valIDators()        return self._valIDators    @valIDators.setter    def valIDators(self,valIDators):        self._valIDators = valIDators    def get_valIDators(self):        return List(self.default_valIDators)

　　

子类

class IntegerFIEld(FIEld):    default_error_messages = {        ‘invalID‘: _(‘A valID integer is required.‘),‘max_value‘: _(‘Ensure this value is less than or equal to {max_value}.‘),‘min_value‘: _(‘Ensure this value is greater than or equal to {min_value}.‘),‘max_string_length‘: _(‘String value too large.‘)    }    MAX_STRING_LENGTH = 1000  # Guard against malicIoUs string inputs.    re_decimal = re.compile(r‘\.0*\s*$‘)  # allow e.g. ‘1.0‘ as an int,but not ‘1.2‘    def __init__(self,**kwargs):        # 从变长传参里找max_value，min_value，给到实例，默认为None        #继承父类的其他属性（相当于父类属性是通用，这里的属性是子类独有的）        self.max_value = kwargs.pop(‘max_value‘,None)        self.min_value = kwargs.pop(‘min_value‘,None)        super().__init__(**kwargs)        # 如果传参max_value，先拼接error message，然后在valIDators属性里添加一个验证器元素。        if self.max_value is not None:            message = lazy_format(self.error_messages[‘max_value‘],max_value=self.max_value)            self.valIDators.append(                MaxValueValIDator(self.max_value,message=message))        if self.min_value is not None:            message = lazy_format(self.error_messages[‘min_value‘],min_value=self.min_value)            self.valIDators.append(                MinValueValIDator(self.min_value,message=message))    def to_internal_value(self,data):        if isinstance(data,str) and len(data) > self.MAX_STRING_LENGTH:            self.fail(‘max_string_length‘)        try:            data = int(self.re_decimal.sub(‘‘,str(data)))        except (ValueError,TypeError):            self.fail(‘invalID‘)        return data    def to_representation(self,value):        return int(value)

　　

class CharFIEld(FIEld):    default_error_messages = {        ‘invalID‘: _(‘Not a valID string.‘),‘blank‘: _(‘This fIEld may not be blank.‘),‘max_length‘: _(‘Ensure this fIEld has no more than {max_length} characters.‘),‘min_length‘: _(‘Ensure this fIEld has at least {min_length} characters.‘),}    initial = ‘‘    def __init__(self,**kwargs):        self.allow_blank = kwargs.pop(‘allow_blank‘,False)        self.trim_whitespace = kwargs.pop(‘trim_whitespace‘,True)        self.max_length = kwargs.pop(‘max_length‘,None)        self.min_length = kwargs.pop(‘min_length‘,None)        super().__init__(**kwargs)        if self.max_length is not None:            message = lazy_format(self.error_messages[‘max_length‘],max_length=self.max_length)            self.valIDators.append(                MaxLengthValIDator(self.max_length,message=message))        if self.min_length is not None:            message = lazy_format(self.error_messages[‘min_length‘],min_length=self.min_length)            self.valIDators.append(                MinLengthValIDator(self.min_length,message=message))        # ProhibitNullCharactersValIDator is None on Django < 2.0        if ProhibitNullCharactersValIDator is not None:            self.valIDators.append(ProhibitNullCharactersValIDator())    def run_valIDation(self,data=empty):        # Test for the empty string here so that it does not get valIDated,# and so that subclasses do not need to handle it explicitly        # insIDe the `to_internal_value()` method.        if data == ‘‘ or (self.trim_whitespace and str(data).strip() == ‘‘):            if not self.allow_blank:                self.fail(‘blank‘)            return ‘‘        return super().run_valIDation(data)    # 将int，float转为为str    def to_internal_value(self,data):        # We‘re lenIEnt with allowing basic numerics to be coerced into strings,# but other types should fail. Eg. unclear if booleans should represent as `true` or `True`,# and composites such as Lists are likely user error.        if isinstance(data,bool) or not isinstance(data,(str,int,float,)):            self.fail(‘invalID‘)        value = str(data)        return value.strip() if self.trim_whitespace else value    def to_representation(self,value):        return str(value)

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