title: Setting a ManyToMany Relationship
body: <p>I'm working on a <code>Django</code> application feature where a restaurant can add extras to his meals. </p>
  
  <p>So I set an <code>extra</code> model with two attributes (extra_n: extra name and extra_price : extra price)</p>
  
  <p>Then I associated this model to the <code>meal</code> model.</p>
  
  <p><strong><em>models.py</em></strong> </p>
  
  <pre><code>class Extra(models.Model):
      extra_n = models.CharField(max_length=200)
      extra_price = models.IntegerField(default=0)
  
      def __str__(self):
          return self.extra_n
  
  class Meal(models.Model):  
      restaurant = models.ForeignKey(Restaurant, on_delete=models.PROTECT)
      category = models.ForeignKey(MealCategory, on_delete=models.PROTECT)
      name = models.CharField(max_length=500)
      short_description = models.CharField(max_length=500)
      image = models.ImageField(upload_to='meal_images/', blank=False)
      price = models.IntegerField(default=0)
      extras = models.ManyToManyField(Extra)
  
      def __str__(self):
         return self.name 
  </code></pre>
  
  <p>I'm having a confusion. The goal is to create extras for each meal. Those extras are going to be associated to one meal and no other.</p>
  
  <p>while checking on the django admin I find that whenever I add an extra, it's associated to all meals.</p>
  
  <p>Can anyone please help figure out the problem ?</p>