title: many-to-many in list display django
body: <pre class="lang-py prettyprint-override"><code>class Product(models.Model):
      products = models.CharField(max_length=256)
      
      def __unicode__(self):
          return self.products
  
  class PurchaseOrder(models.Model):
      product = models.ManyToManyField('Product')
      vendor = models.ForeignKey('VendorProfile')
      dollar_amount = models.FloatField(verbose_name='Price')
  </code></pre>
  <p>I have that code. Unfortunately, the error comes in admin.py with the <code>ManyToManyField</code></p>
  <pre><code>class PurchaseOrderAdmin(admin.ModelAdmin):
      fields = ['product', 'dollar_amount']
      list_display = ('product', 'vendor')
  </code></pre>
  <p>The error says:</p>
  <blockquote>
  <p>'PurchaseOrderAdmin.list_display[0]', 'product' is a ManyToManyField
  which is not supported.</p>
  </blockquote>
  <p>However, it compiles when I take <code>'product'</code> out of <code>list_display</code>. So how can I display <code>'product'</code> in <code>list_display</code> without giving it errors?</p>
  <p><strong>edit</strong>: Maybe a better question would be how do you display a <code>ManyToManyField</code> in <code>list_display</code>?</p>