title: Django Serializers with Foreign Key not working
body: <p>I want to create a ListCreateView for my models. 
  Here is are models - </p>
  
  <pre><code>from django.db import models
  
  from training_service.models.advertiser import Advertiser
  
  class Config(models.Model):
      CONFIG_TYPE_CHOICES = (
          ('DATA_DESCRIPTOR', 'DATA_DESCRIPTOR'),
          ('DATAFETCH', 'DATAFETCH'),
          ('BATCHSYSTEM', 'BATCHSYSTEM'),
          ('SPARKSYSTEM', 'SPARKSYSTEM')
      )
  
      id = models.AutoField(primary_key=True)
      name = models.CharField(max_length=100)
      config_type = models.CharField(max_length=100,
                                     choices=CONFIG_TYPE_CHOICES,
                                     blank=False)
      default_value = models.CharField(max_length=1000)
  
      class Meta:
          db_table = 'config'
  
      def __unicode__(self):
          return str(self.name)
  
  class AdvertiserConfig(models.Model):
      advertiser_id = models.ForeignKey(
          Advertiser, to_field="advertiser_id", db_column="advertiser_id", on_delete=models.DO_NOTHING)
      config_id = models.ForeignKey(Config, on_delete=models.CASCADE)
      value = models.CharField(max_length=1000)
  
      class Meta:
          db_table = 'advertiser_config'
  
      def __unicode__(self):
          return str(self.name)
  </code></pre>
  
  <p>Below are the serializers for the models - </p>
  
  <pre><code>class ConfigSerializer(serializers.ModelSerializer):
      class Meta:
          model = Config
          fields = ('name', 'config_type', 'value_type', 'default_value')
  
  class AdvertiserConfigSerializer(serializers.ModelSerializer):
      config_name = serializers.PrimaryKeyRelatedField(read_only=True, many=True)
      class Meta:
          model = AdvertiserConfig
          fields = ('advertiser_id', 'config_name', 'value')
  </code></pre>
  
  <p>But this is not working when I do a get on AdvertiserConfig I am not getting config_name in the response. And no error is thrown.</p>
  
  <p>Any idea what is wrong here? 
  Also how would I do a create for AdvertiserConfig? </p>