CODEWITHSUNDEEP
djangodjango-modelsdjango-rest-frameworkdjango-views
Pradyum Gupta
Pradyum Gupta

Reputation: 317

Django ManytoManyfields error `AttributeError: 'ManyRelatedManager' object has no attribute 'dev_id'`

I guess there is already been a lot of discussions available almost went through all of them but still facing this error.

class Device(models.Model):
    """Storing Device ids """
    platform  = models.CharField(max_length=3, choices=PLATFORM, default = 'ANR')
    dev_id    = models.CharField(max_length = 255, null=True, blank=False)
​
    def __str__(self):
        return str(self.id)


class UserProfile(models.Model):
    user             = models.OneToOneField('user.User', 
                                         on_delete=models.CASCADE,
                                         related_name='profile',
                                         primary_key=True,
                                         unique=True)
    device           = models.ManyToManyField(Device, related_name='devices')
​
    def __str__(self):
        return str(self.user)

Error 1

username = UserProfile.objects.filter(
                    phone_number=user_username).get()
username.device.dev_id
*** AttributeError: 'ManyRelatedManager' object has no attribute 'dev_id'

Error 2 After Some Research


username.device.values_list('dev_id', flat=True)
<QuerySet []>
​```

There is no device found with this user but there are devices in them for this username
For the reference, I have listed devices

```python
>>> Device.objects.all()
<QuerySet [<Device: 1>]>

Error 3

(Pdb) username.device.all()
<QuerySet []>
 Checked with this Method but not able to list devices

Upvotes: 2

Views: 14176

Answers (1)

Hafnernuss
Hafnernuss

Reputation: 2847

This cannot work, because device is a ManyToMany Relationship. A user can obviously have multiple devices (or none) associated.

If you want to access all devices from a user, try the following:

user.device.all()

this will give you a QuerySet from a RelatedManager. Just use it like a regular QuerySet:

for d in user.device.all():
  print(d.dev_id)

This, of course, is described in the documentation.

Upvotes: 14

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