title: Django query many-to-many field
body: <p>I have these two models.</p>
  
  <pre><code>class Tickets(models.Model):
      id = models.CharField(primary_key=True, max_length=12)
      recipients = models.ManyToManyField(CustomUser)
      title = models.CharField(blank=True, max_length=100)
  
  class CustomUser(AbstractBaseUser, PermissionsMixin):
      email = models.EmailField(primary_key=True,)
      user_name = models.CharField(blank=False, max_length=20)
  </code></pre>
  
  <p>In Tickets model, recipients may include multiple users. <br/>
  I'm trying to <br/>
  1. Read how many tickets does specific user has. <br/>
  2. Regroup Tickets by recipients to get this kind of output in template.<br/></p>
  
  <pre><code>user_name1
     Ticket.id
     Ticket.title
  user_name2
     Ticket.id
     Ticket.title
  user_name3
     Ticket.id
     Ticket.title
  </code></pre>
  
  <p>I was trying really hard on "regroup", but not much result...<br/>
  Could someone give me some guidance?</p>