title: How to do an "OneToMany(Field)" relationship in Django?
body: <p>I know that there is no OneToManyField. But in this situation I need one. </p>
  
  <p>I want to save many Image objects to one Advertisement object. How can I achieve this ?</p>
  
  <p>I have the following situation:</p>
  
  <p><strong>models.py</strong></p>
  
  <pre><code>class Image(models.Model):
     id = models.AutoField(primary_key=True)
     image = models.ImageField(upload_to="", default="", null=True)
  
     def __str__(self):
         return self.image.url
  
  class Advertisement(models.Model):
      id = models.AutoField(primary_key=True)
      user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='user', null=True)
      category = models.ForeignKey(Category, related_name='category', null=True)
      title = models.CharField(max_length=100, null=True)
      description = models.CharField(max_length=5000, null=True)
      date = models.DateTimeField(auto_now_add=True, null=True)
  
      def __str__(self):
          return self.description
  </code></pre>