ManyToMany Relationships. Returning fields in def __str__ method
<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>