title: ManyToMany Relationships. Returning fields in def __str__ method
body: <p>I have two models:</p>
  
  <p><code>AffectedSegment</code> model</p>
  
  <pre><code>class AffectedSegment(models.Model):
  
      SEGMENTO_ESCAPULA = 'Escápula'
      SEGMENTO_HOMBRO = 'Hombro'
      SEGMENTO_CODO = 'Codo'
      SEGMENTO_ANTEBRAZO = 'Antebrazo'
      SEGMENTO_CARPO_MUNECA = 'Carpo/Muñeca'
      SEGMENTO_MANO = 'Mano'
      SEGMENT_CHOICES = (
          (SEGMENTO_ESCAPULA, u'Escápula'),
          (SEGMENTO_HOMBRO, u'Hombro'),
          (SEGMENTO_CODO, u'Codo'),
          (SEGMENTO_ANTEBRAZO, u'Antebrazo'),
          (SEGMENTO_CARPO_MUNECA, u'Carpo/Muñeca'),
          (SEGMENTO_MANO, u'Mano'),
      )
  
      affected_segment = models.CharField(
          max_length=12,
          choices=SEGMENT_CHOICES,
          blank=False,
          verbose_name='Segmento afectado',
          help_text='Ingrese uno o mas segmentos corporal de miembros superiores'
      )
  
      class Meta:
          verbose_name_plural = 'Segmentos corporales'
  
      def __str__(self):
          return "%s" % self.affected_segment
  </code></pre>
  
  <p>And <code>Movement</code> model. Please review the <code>__str__</code> method of this model at the end:</p>
  
  <pre><code>class Movement(models.Model):
      type = models.CharField(
          max_length=255,
          verbose_name='Tipo de movimiento'
      )
  
      corporal_segment_associated = models.ManyToManyField(
          AffectedSegment,
          blank=True,
          verbose_name='Segmento corporal asociado')
  
      class Meta:
          verbose_name = 'Movimiento'
  
      def __str__(self):
          return "{},{}".format(self.type, self.corporal_segment_associated)
  </code></pre>
  
  <p>I have another model named <code>RehabilitationSession</code> in which I want allow the possibility of choose multiple affected_segments and multiple movements such as follow:</p>
  
  <p>class RehabilitationSession(models.Model):</p>
  
  <pre><code>affected_segment = models.ManyToManyField(
      AffectedSegment,
      verbose_name='Segmento afectado',
      #related_name='affectedsegment'
  )
  movement = models.ManyToManyField(
      Movement,  # Modelo encadenado
      verbose_name='Movimiento',
      #related_name = 'movement'
  )
  </code></pre>
  
  <p>In my Django Admin when I go to the <code>RehabilitationSession</code> model I see the following in the <code>movement</code> field:</p>
  
  <p><a href="https://i.stack.imgur.com/rgDn7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rgDn7.png" alt="enter image description here"></a></p>
  
  <p>I understand that in the <code>ManyToMany</code> relationships, a intermediate table is created with the ID's fields of the two tables which make the <code>m2m</code> relationship of this way:</p>
  
  <p><a href="https://i.stack.imgur.com/qFuVz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qFuVz.png" alt="enter image description here"></a></p>
  
  <p>My question is:</p>
  
  <p>How to can I make that in my <code>Movement</code> model I can access to the <code>corporal_segment_associated</code> field that I want call in the <code>__str__</code> method?</p>
  
  <p>Any orientation is very useful
  :)</p>