title: Django REST Framework (DRF): Set current user id as field value
body: <p>I have model NewsModel and 2 serializers for him:</p>
  
  <p><strong>models.py</strong></p>
  
  <pre><code>class NewsModel(models.Model):
      title = models.CharField('Заголовок', max_length=255, help_text='Максимальная длина - 255 символов')
      announce = models.TextField('Анонс', help_text='Краткий анонс новости')
      author = models.ForeignKey(settings.AUTH_USER_MODEL, help_text='Автор новости', related_name='news')
      full_text = models.TextField('Полный текст новости', help_text='Полный текст новости')
      pub_date = models.DateTimeField('Дата публикации', auto_now_add=True, default=timezone.now, help_text='Дата публикации')
  
      def comments_count(self):
          return NewsComment.objects.filter(news=self.id).count()
  
      def get_author_full_name(self):
          return self.author.get_full_name()
  
      class Meta:
          db_table = 'news'
          ordering = ('-pub_date',)
  </code></pre>
  
  <p><strong>serilizers.py:</strong></p>
  
  <pre><code>from rest_framework import serializers
  from .models import NewsModel
  from extuser.serializers import UserMiniSerializer
  
  class NewsReadSerializer(serializers.ModelSerializer):
  
      author = UserMiniSerializer()
  
      class Meta:
          model = NewsModel
          fields = ('id', 'title', 'announce', 'comments_count', 'reviews', 'author_name')
  
      def get_author_full_name(self, obj):
          return obj.get_author_full_name()
  
  
  class NewsWriteSerializer(serializers.ModelSerializer):
  
      def validate_author(self, value):
          value = self.request.user.id
          return value
  
      class Meta:
          model = NewsModel        
  </code></pre>
  
  <p>I select serializers in the <strong>api.py</strong>:</p>
  
  <pre><code>class NewsList(ListCreateAPIView):
      queryset = NewsModel.objects.order_by('-pub_date')
      def get_serializer_class(self, *args, **kwargs):
          if self.request.method == 'GET':
              return NewsReadSerializer
          return NewsWriteSerializer
  
      class Meta:
          model = NewsModel
  </code></pre>
  
  <p>But when I will create NewsModel item, I see <em>Error 400: Bad request [{'author': 'This field is required'}]</em></p>
  
  <p>How I can set current user id as NewsItem.author value on creating new item?</p>