title: Get selected values of ManytoMany field in django model save method
body: <p>I am trying to add data to a table <strong>BillRecord</strong> from Django admin.I need to access selected values of <strong>ManytoMany</strong> field in model <strong>save</strong> method and need to do some logic depending upon the selected objects of ManytoMany field.  </p>
  
  <pre><code>class ProductType(BaseApplicationModel):
     name = models.CharField(max_length=128)
  
  class Product(BaseApplicationModel)
     type = models.ForeignKey(ProductType,related_name="products")
  
  class BillRecord(BaseApplicationModel):
      products = models.ManyToManyField(Product, related_name="billrecords")
  
      def save(self, *args, **kwargs):
         super(BillRecord, self).save(*args, **kwargs)
         for product in self.products.all():
            print product
  </code></pre>
  
  <p>In the code when I tried to print the values of product it gives me <code>billing.Product.None</code> that is <code>self.products.all()</code> returns empty queryset</p>
  
  <p>I need to get the ID's of the selected objects in the ManyToMany field select box. <img src="https://i.stack.imgur.com/ajiYy.png" alt="picture"> </p>