CODEWITHSUNDEEP
pythondjangomany-to-many
NakedPython
NakedPython

Reputation: 930

Creating new object returns field with None value

I'm trying to create a new object of my model, but keep on getting a value of none for one field.

My models look like this:

class KeyCategory(models.Model):
    program = models.ForeignKey('Program', verbose_name='Programm', on_delete=models.CASCADE)
    name = models.CharField('Name', max_length=100)
    events = models.ManyToManyField('Event', through='EventQuota')

    class Meta:
        verbose_name = 'Category'
        verbose_name_plural = 'Categories'
        ordering = ['name']
        unique_together = ("program", "name")
        permissions = (
            ('view_key_category', 'Have access to categories'),
        )


class EventQuota(models.Model):
    key_category = models.ForeignKey(KeyCategory, on_delete=models.CASCADE, related_name='key_quota')
    event = models.ForeignKey('Event', on_delete=models.CASCADE, related_name='key_quota')
    quota = models.PositiveIntegerField('Quota', default=0)

    class Meta:
        verbose_name = 'Quota'
        verbose_name_plural = 'Quotas'
        unique_together = ('key_category', 'event')

When I try now to create a KeyCategory and my EventQuota, the field "events" for KeyCategory always returns core.Event.None 

        if program.pk == 1:
            for _ in range(0, 2):
                key_category = KeyCategory(
                    program=program,
                    name=random.choice(self.eventList)
                )
                key_category.save()
                event_quota = EventQuota(
                    key_category=key_category,
                    event = random.choice(eventList),
                    quota = random.randint(0,100)
                )
                event_quota.save()

Note: the eventList in the random.choice is a queryset list of objects.

I tried to follow Djangos Extra fields on Many-to-Many relationships example, but somehow it seems that I'm missing something here or doing something not the right way? Would appreciate any help! Thanks in regard.

Logging:

import logging
logger = logging.getLogger(__name__)
logger.debug(key_category.events)

Upvotes: 0

Views: 71

Answers (1)

Scott Evans
Scott Evans

Reputation: 373

When you access key_category.events you are asking for the value of a field (or a single object for foreign key fields). However with a ManyToMany relationship you are asking for multiple objects (a queryset). Using key_category.events.all() returns the objects related to the key_category, not just a single value.

core.events.all()

Upvotes: 1

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