title: Listing Related Fields in Django ModelAdmin
body: <p>I'm listing a model in Django's admin via a <code>TabularInline</code>. Inside this inline, I'd like to use Django's model traversal syntax to list data in other models referenced from this model via foreign keys. e.g.</p>
  <pre><code>class MyRelatedModel(models.Model):
      name = models.CharField(max_length=50)
      created = models.DateField(auto_now_add=True)
      other = models.ForeignKey('MyOtherRelatedModel')
  
  class MyOtherRelatedModel(models.Model):
      name = models.CharField(max_length=50)
      created = models.DateField(auto_now_add=True)
          
  class MyRelatedModelInline(admin.TabularInline):
      model = MyRelatedModel
      fields = ['name', 'created', 'other__name']
      #readonly_fields = ['name', 'created', 'other__name']
  </code></pre>
  <p>However, the usage of 'other__name' throws the ImproperlyConfigured error:</p>
  <pre><code>'MyRelatedModelInline.fields' refers to field 'other__name' that is missing from the form
  </code></pre>
  <p>Is the model traversal syntax not supported in ModelAdmin instances? If it is supported, what am I doing wrong?</p>
  <p>EDIT: If I uncomment readonly_fields, the error becomes:</p>
  <pre><code>Caught AttributeError while rendering: 'MyMainModelAdmin' object has no attribute '__name__'
  </code></pre>