title: How to get foreignkey field name instead of id in django rest framework
body: <p>Here is my models.py</p>
  
  <pre><code>from __future__ import unicode_literals
  from django.db import models
  
  class User(models.Model):
      name = models.CharField(max_length=200)
      company_name = models.ForeignKey('Company',on_delete=models.CASCADE,related_name='user')
  
      def __str__(self):
          return self.name
  
  class Company(models.Model):
      name = models.CharField(max_length=200)
      phone_number = models.IntegerField(null=True,blank=True)
  
      def __str__(self):
          return self.name
  
  class Catalog(models.Model):
      name = models.CharField(max_length=200)
      no_of_pcs = models.IntegerField(null=True,blank=True)
      per_piece_price = models.DecimalField(null=True,blank=True,max_digits=10,decimal_places=2)
      company_name = models.ForeignKey(Company,on_delete=models.CASCADE,related_name='catalog')
  
      def __str__(self):
          return self.name
  </code></pre>
  
  <p>here is my serializers.py</p>
  
  <pre><code>from rest_framework import serializers
  from .models import *
  from django.db.models import Sum,Count
  
  class UserSerializer(serializers.ModelSerializer):
      # name = serializers.StringRelatedField()
      # company_name = serializers.CharField()
      class Meta:
          model = User
          fields = '__all__'
  </code></pre>
  
  <p>here is my views.py</p>
  
  <pre><code>from __future__ import unicode_literals
  from django.http import HttpResponse
  from .models import *
  import json
  from django.http import JsonResponse, HttpResponse
  from .serializers import *
  from rest_framework.views import APIView
  from rest_framework.response import Response
  from rest_framework import status
  from rest_framework import viewsets
  
  class UserView(viewsets.ModelViewSet):
      queryset =  User.objects.all()
      serializer_class = UserSerializer
  </code></pre>
  
  <p>I am getting api like this..
  Here i am getting id instead of company_name.</p>
  
  <pre><code>[
      {
          "id": 1,
          "name": "soubhagya",
          "company_name": 1
      },
      {
          "id": 2,
          "name": "nihar",
          "company_name": 2
      }
  ]
  </code></pre>
  
  <p>But i am expecting output--</p>
  
  <p>like this:</p>
  
  <pre><code>[
      {
          "id": 1,
          "name": "soubhagya",
          "company_name": "google"
      },
      {
          "id": 2,
          "name": "nihar",
          "company_name": "facebook"
      }
  ]
  </code></pre>
  
  <p>I am expecting my api like this. with company_name.
  And i wants to post the data from same api in rest framework
  thanks,,</p>