Question

I have few models in Django:

from django.db import models

class First(models.Model):
    first_name = models.CharField('First Name', max_length=100)
    first_value = models.IntegerField('Value')

    def __unicode__(self):
        return self.first_name 

class Second(models.Model):
    first_ref = models.ForeignKey(First)
    second_name = models.CharField('Second Name', max_length=100)
    second_value = models.IntegerField('Second Value')

    def __unicode__(self):
        return self.second_name

class Third(models.Model):
    second_ref = models.ForeignKey(Second)
    third_name = models.CharField('Third Name', max_length=100)
    third_value = models.IntegerField('Third Value')

    def __unicode__(self):
        return self.third_name

Now, when I try to add a new record for Third model in my Django admin, my <select> box is populated with second_name values. How can I display a concatenated string of different values from both ‘parent’ tables, e.g. first_name + first_value + second_name + second_value?

Answer 1

Just update the unicode method of second Model:

class Second(models.Model):
    first_ref = models.ForeignKey(First)
    second_name = models.CharField('Second Name', max_length=100)
    second_value = models.IntegerField('Second Value')

    def __unicode__(self):
        return '%s %s %s %s' % (
            self.first_ref.first_name, self.first_ref.first_value,
            self.second_name, self.second_value)