title: django-rest-framerwork serializer how to get user id
body: <p>a model like this:</p>
  
  <pre><code>class Album(models.Model):
      artist = models.ForeignKey(Musician, on_delete=models.CASCADE)
      name = models.CharField(max_length=100)
      release_date = models.DateField()
      num_stars = models.IntegerField()
  </code></pre>
  
  <p>and serializer:</p>
  
  <pre><code>class AlbumSerializers(serializers.ModelSerializer):
      count=serializers.SerializerMethodField()
      class Meta:
          module=Album
          fields=('__all__')
  </code></pre>
  
  <p>I just want know how can I get user.id in serializer</p>