title: Object in django admin for a foreignkey :
body: <p>I have this object in my django model : </p>
  
  <pre><code>class Stock(models.Model):
      name =  models.CharField(null=True,blank=True,max_length=20)
      def ___str__(self):
          return self.name
      def __unicode__(self):
          return self.name
  </code></pre>
  
  <p>When I see it in the django admin it works well.</p>
  
  <p>But in the admin when I want to see this object : </p>
  
  <pre><code>class StockData(models.Model):
      stock = models.ForeignKey(Stock,on_delete=models.PROTECT,null=True,blank=True)
      date = models.DateTimeField(null=True,blank=True)
      interval = models.CharField(null=True, blank=True,max_length=2)
  
      def ___str__(self):
          return self.stock+ ":" + str(self.date)
      def __unicode__(self):
          return self.stock + ":" + str(self.date)
  </code></pre>
  
  <p>with this admin : </p>
  
  <pre><code>from django.contrib import admin
  from .models import StockData
  
  # Register your models here.
  class StockData_Admin(admin.ModelAdmin):
      list_display = (
          'date',
          'stock',
          'interval'
      )
  
  admin.site.register(StockData,StockData_Admin)
  </code></pre>
  
  <p>but in the admin page the stock object is represented as : </p>
  
  <pre><code>Stock object (1)
  </code></pre>
  
  <p>edit : </p>
  
  <p><a href="https://i.stack.imgur.com/TvrHI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TvrHI.png" alt="enter image description here"></a></p>
  
  <p>So how to solve this ?</p>
  
  <p>My django version :</p>
  
  <pre><code>&gt;&gt;&gt; import django
  &gt;&gt;&gt; django.VERSION 
  (2, 0, 0, 'final', 0)
  </code></pre>
  
  <p>Thanks and regards</p>