Django learning 13-validator

  You always have to pay when you come out, but you ca n’t be lazy for a while, and the accounts you owe you will have to be settled sooner or later.
  Before being lazy, I did not verify the data entry in the background of the system, but just identified the wrong data in the foreground and urged the second modification; the year-end data inspection found that there was no problem with some data entry but the logical relationship between the data was wrong, without verification, multi-dimensional Verification is difficult to prove.
  Well, it ’s time to pay back, re-enter, continue to learn, use django ’s validator function for data entry verification.

  参考《Django Documentation》，6.27，validators

1. django标准validator，即内建的验证方法（Build-in Validator）
   1）RegexValidator
         validate_slug / validate_unicode_slug / validate_ipv4_address / validate_ipv6_address
         validate_ipv46_address / validate_comma_separated_integer_list / int_list_validator
   2）EmailValidator / validate_email
   3）URLValidator
   4）MaxValueValidator / MinValueValidator
   5）MaxLengthValidator / MinLengthValidator
   6）DecimalValidator
   7）FileExtensionValidator
   8）validate_image_file_extension
   9）ProhibitNullCharactersValidator
    
2. Custom validator method
   1) Reference validators, from django.core import validators
   2) Reference validation
   error, from django.core.exceptions import ValidationError 2) Custom validator method, called in Form or Model
3. 调用 validator
   1） Build-in Vallidator

   # using in module
   # format: validators=[Build-in Validator(parameters)]  
   
   例：
   
   django.core.validators    # module contains a collection of callable validators
                             # for use with model and form field'''
   
   field_name = models.TextField(..., validators=[MinLengthValidator(20, message='not less than 10')],...)  
   
   
   

   2) Custom validator

   from django.core.exceptions import ValidationError
   
   # 自定义 validator 
   def <selfdefine_validator(value)>:
        if value match condition:
            raise ValidationError("Error Message")
   
   # model中调用自定义 validator
   field_name = models.TextField(..., validators=[selfdefine_validator(), ],...)  

   3）Run in forms：form validation （6.12.7 Form and field validation）

   # view.py中定义页面元素，并进行验证
   
   from django.forms import Form, fields, widgets

   4）Run in modelsValidating objects（6.15 Models）
         step 1: Validate the model fields - Model.clean_fields()
         step 2: Validate the model as a whole - Model.clean()
         step 3: Validate the field uniqueness - Model.validate_unique()

   from django.core.exceptions import ValidationError
   
   # models中定义 clean() 方法
   def clean(self):
       field_value = self.field_name  # 保存(save)前通过字段名(field_name)获取字段输入值(field_value)
       ......
   
       if field_value满足条件：
           raise ValidationError()
   
   # 1. 特定的某个字段错误信息提示
   raise ValidationError({'field_name':'Error Message',})
   
   # 2. 特定的某些字段错误信息提示
   raise ValidationError({'field_name1':'Error Message',
                          'field_name2':'Error Message', 
                          ......,
                           })
   
   # 3. 页面错误信息提示
   raise ValidationError('Error Message')