title: Fetch data from size table by getting id from mapping table in django?
body: <p>I am creating a printing ordering service website in django and i am stuck on order page.
  I have three tables named &quot;product&quot; ,&quot;size&quot; and &quot;sizeProductMap&quot; table.</p>
  <p><em><strong>model.py</strong></em></p>
  <p>This is my product table.</p>
  <pre><code>class Product(models.Model):
      prod_ID = models.AutoField(&quot;Product ID&quot;, primary_key=True)
      prod_Name = models.CharField(&quot;Product Name&quot;, max_length=30, null=False)
      prod_Desc = models.CharField(&quot;Product Description&quot;, max_length=2000, null=False)
      prod_Price = models.IntegerField(&quot;Product Price/Piece&quot;, default=0.00)
      prod_img = models.ImageField(&quot;Product Image&quot;,upload_to='productImage/', null=True)
  </code></pre>
  <p>This is the size table.</p>
  <pre><code>class Size(models.Model):
      size_id = models.AutoField(&quot;Size ID&quot;, primary_key=True, auto_created=True)
      prod_size = models.CharField(&quot;Product Size&quot;, max_length=20, null=False)
  </code></pre>
  <p>This is the sizeProductMapping table.</p>
  <pre><code>class SizeProductMapping(models.Model):
      size_p_map_id = models.AutoField(&quot;Size &amp; Product Map ID&quot;, primary_key=True, auto_created=True)
      size_id = models.ForeignKey(Size, null=False, on_delete=models.CASCADE, verbose_name=&quot;Size ID&quot;)
      prod_id = models.ForeignKey(Product, null=False, on_delete=models.CASCADE, verbose_name=&quot;Product Id&quot;)
  </code></pre>
  <p>The sizeProductMap tables stores primary key of product table and size table as foreign key, now i want to get those sizes which has mapping with a particular product.</p>
  <p>I want to get all those sizes from size table releted to a particular product here a single product can have different sizes.</p>