Django Rest Framework - how to create custom error messages for all ModelSerializer fields?

问题

This is my serializers.py (I want to create a serializer for the built-in User model):

from rest_framework import serializers

from django.contrib.auth.models import User

class UserSerializer(serializers.ModelSerializer):

    class Meta:
        model = User
        fields = ('username', 'password', 'email', )

I'm aware that Django Rest Framework has it's own field validators, because when I try to create a user using a username which already exists, it raises an error saying:

{'username': [u'This field must be unique.']}

I want to customize the error message and make it say "This username is already taken. Please try again" rather than saying "This field must be unique".

It also has a built-in regex validator, because when I create a username with an exclamation mark, it says:

{'username': [u'Enter a valid username. This value may contain only letters, numbers and @/./+/-/_ characters.']}

I want to customize the regex validator so that it just says "Invalid username".

How do I customize all of the error messages which each field has?

Note: according to this post: Custom error messages in Django Rest Framework serializer I can do:

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User

    def __init__(self, *args, **kwargs):
        super(UserSerializer, self).__init__(*args, **kwargs)

        self.fields['username'].error_messages['required'] = u'My custom required msg'

But what do I do for the 'unique' and 'regex' validators? I tried doing

self.fields['username'].error_messages['regex'] = u'My custom required msg'

and

self.fields['username'].error_messages['validators'] = u'My custom required msg'

but neither worked.

回答1:

In order to replace unique or regex error messages you should change message member of corresponding validator object. This could be done using separate mixin class:

from django.core.validators import RegexValidator
from rest_framework.validators import UniqueValidator
from django.utils.translation import ugettext_lazy as _


class SetCustomErrorMessagesMixin:
    """
    Replaces built-in validator messages with messages, defined in Meta class. 
    This mixin should be inherited before the actual Serializer class in order to call __init__ method.

    Example of Meta class:

    >>> class Meta:
    >>>     model = User
    >>>     fields = ('url', 'username', 'email', 'groups')
    >>>     custom_error_messages_for_validators = {
    >>>         'username': {
    >>>             UniqueValidator: _('This username is already taken. Please, try again'),
    >>>             RegexValidator: _('Invalid username')
    >>>         }
    >>>     }
    """
    def __init__(self, *args, **kwargs):
        # noinspection PyArgumentList
        super(SetCustomErrorMessagesMixin, self).__init__(*args, **kwargs)
        self.replace_validators_messages()

    def replace_validators_messages(self):
        for field_name, validators_lookup in self.custom_error_messages_for_validators.items():
            # noinspection PyUnresolvedReferences
            for validator in self.fields[field_name].validators:
                if type(validator) in validators_lookup:
                    validator.message = validators_lookup[type(validator)]

    @property
    def custom_error_messages_for_validators(self):
        meta = getattr(self, 'Meta', None)
        return getattr(meta, 'custom_error_messages_for_validators', {})

Then you could just inherit this mixin and update Meta class:

class UserSerializer(SetCustomErrorMessagesMixin, serializers.HyperlinkedModelSerializer):
    class Meta:
        model = User
        fields = ('url', 'username', 'email', 'groups')
        custom_error_messages_for_validators = {
            'username': {
                UniqueValidator: _('This username is already taken. Please, try again'),
                RegexValidator: _('Invalid username')
            }
        }

来源：https://stackoverflow.com/questions/30565389/django-rest-framework-how-to-create-custom-error-messages-for-all-modelseriali