Model详解

1、Model的功能

数据库操作

a、建表

　　表字段

　　表字段参数

　　Meta参数

b、表关系

　　一对一

　　一对多

　　多对多

　　各种表关系参数

c、表操作

　　基本操作

　　进阶操作

　　高级操作

　　其他操作

数据字段验证

full_clean()====>clean_fields()

　　　　　====>clean()

full_clean函数

参数

• 参数1、exclude
• 参数2、validate_unique

调用过程：

• 调用clean_fields
• 调用clean
• 调用validate_unique

    def full_clean(self, exclude=None, validate_unique=True):
        """
        Calls clean_fields, clean, and validate_unique, on the model,
        and raises a ``ValidationError`` for any errors that occurred.
         调用clean_fields, clean, and validate_unique,在model里raise错误        
        ValidationError
        """
        errors = {}
        if exclude is None:
            exclude = []
        else:
            exclude = list(exclude)

        try:
            self.clean_fields(exclude=exclude)
        except ValidationError as e:
            errors = e.update_error_dict(errors)

        # Form.clean() is run even if other validation fails, so do the
        # same with Model.clean() for consistency.
        try:
            self.clean()
        except ValidationError as e:
            errors = e.update_error_dict(errors)

        # Run unique checks, but only for fields that passed validation.
        if validate_unique:
            for name in errors.keys():
                if name != NON_FIELD_ERRORS and name not in exclude:
                    exclude.append(name)
            try:
                self.validate_unique(exclude=exclude)
            except ValidationError as e:
                errors = e.update_error_dict(errors)

        if errors:
            raise ValidationError(errors)       

　　

clean_fields函数

    def clean_fields(self, exclude=None):
        """
        Cleans all fields and raises a ValidationError containing a dict
        of all validation errors if any occur.
         清洗所有字段，并且抛出ValidationError异常，所有发生的错误都包含在一个字典中。
        """
        if exclude is None:
            exclude = []

        errors = {}
        for f in self._meta.fields:
            if f.name in exclude:
                continue
            # Skip validation for empty fields with blank=True. The developer
            # is responsible for making sure they have a valid value.
            raw_value = getattr(self, f.attname)
            if f.blank and raw_value in f.empty_values:
                continue
            try:
                setattr(self, f.attname, f.clean(raw_value, self))
            except ValidationError as e:
                errors[f.name] = e.error_list

        if errors:
            raise ValidationError(errors)

　　

clean（）函数

    def clean(self):
        """
        Hook for doing any extra model-wide validation after clean() has been
        called on every field by self.clean_fields. Any ValidationError raised
        by this method will not be associated with a particular field; it will
        have a special-case association with the field defined by NON_FIELD_ERRORS.
       #clean函数是一个钩子，调用clean_fields就会调用clean函数，
        """
        pass

　　

数据字段正则判断

error_messages      自定义错误信息（字典类型），从而定制想要显示的错误信息；
                        字典健：null, blank, invalid, invalid_choice, unique, and unique_for_date
                        如：{'null': "不能为空.", 'invalid': '格式错误'}

validators          自定义错误验证（列表类型），从而定制想要的验证规则
                        from django.core.validators import RegexValidator
                        from django.core.validators import EmailValidator,URLValidator,DecimalValidator,\
                        MaxLengthValidator,MinLengthValidator,MaxValueValidator,MinValueValidator
                        如：
                            test = models.CharField(
                                max_length=32,
                                error_messages={
                                    'c1': '优先错信息1',
                                    'c2': '优先错信息2',
                                    'c3': '优先错信息3',
                                },
                                validators=[
                                    RegexValidator(regex='root_\d+', message='错误了', code='c1'),
                                    RegexValidator(regex='root_112233\d+', message='又错误了', code='c2'),
                                    EmailValidator(message='又错误了', code='c3'), ]





# Create your models here.
class News(models.Model):
    title = models.CharField(max_length=10,
                             error_messages={'c1': '.....'},
                             validators=[
                                 RegexValidator(regex='root_\d+', message='错误了', code='c1'),]
                             )
    favor = models.ManyToManyField('User', through="Favor", through_fields=("new_obj", 'user_obj'))


    def clean(self):
        self.title

　　

2、Model的总结

Model：具有强大的数据库操作（建表、确定表之间的关系、表的操作）

　　　　较弱的数据验证（专门针对字段定义错误、或者正则错误）

　　　　内置钩子数据验证（验证功能比较弱化，清洗字段主要是靠自定义错误）