title: How to order readonly M2M fields in django admin
body: <p>I can't seem to work out how to hook into the queryset of a readonly field in Django admin. In particular I want to do this for an inline admin.</p>
  
  <pre><code># models.py
  class Value(models.Model):
      name = models.TextField()
  
  class AnotherModel(models.Model):
      values = models.ManyToManyField(Value)
  
  
  class Model(models.Model):
      another_model = models.ForeignKey(AnotherModel)
  
  
  # admin.py
  class AnotherModelInline(admin.TabularInline):
      # How do I order values by 'name'?
      readonly_fields = ('values',)
  
  
  class ModelAdmin(admin.ModelAdmin):
      inlines = (AnotherModelInline,)
  </code></pre>
  
  <p>Note that this could probably be done by overriding the form and then setting the widget to disabled, but that's a bit of a hack and doesn't look nice (I don't want greyed out multi-select, but a comma-separated list of words.</p>