return multiple objects with same name

Question

MultipleObjectsReturned at /user/(name of object)/ Exception Type: MultipleObjectsReturned

Request Method: GET

Exception Value: get() returned more than one Canvas -- it returned 2!

Exception Location: C:\Users\user\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\models\query.py in get, line 389

Multiple objects with the same name, but a user can only have one unique object name.

Whenever I create another object with the same name I get this error (MultipleObjectsReturned). I want to allow every user to create one unique object name.

For example: user1 can have a unique object name of (test) and user2 can also have a unique object name of (test).

class Object(models.Model):
    user                = models.ForeignKey(settings.AUTH_USER_MODEL, default=1)
    object_name         = models.CharField(
                        max_length=100,
                        validators=[
                            # validate_canvas_title,
                            RegexValidator(
                                    regex=CANVAS_REGEX,
                                    message='Canvas must only contain Alpahnumeric characters',
                                    code='invalid_canvas_title'
                                )],
                        )
    slug                = models.SlugField(max_length=100, blank=True)

    class Meta:
        unique_together = ['user', 'object_name']

view

def canvasView(request, username=None, slug=None):
    user = User.objects.get(username__iexact=username)
    object = get_object_or_404(Object, slug__iexact=slug)

    template = "pages/object.html"
    context = {
        'user' : user,
        'object': object,
    }
    return render(request, template, context)

Daniel Roseman · Accepted Answer · 2017-05-15 09:51:35Z

1

You need to use the user in the query.

object = get_object_or_404(Object, user=user, slug__iexact=slug)

answered May 15, 2017 at 9:51

Daniel Roseman

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2 Comments

lolz Over a year ago

How would i get the object through the user. do i user user.object_set.all(), and then filter?

Daniel Roseman Over a year ago

Yes you could do user.object_set.get(slug__iexact=slug), but then you would have to catch the ObjectNotFound exception and raise 404.

zaidfazil · Accepted Answer · 2017-05-15 10:50:24Z

The get_object_or_404 function returns the object, which satisfies the condition specified, the thing to keep in my mind is that there should only be a single object with the specified condition. It doesn't return a list or anything like that. If multiple objects are found, then it returns the so called error.

You need to pass user into the arguments,

object_name = get_object_or_404(Object, user=user, slug__iexact=slug)

Or you could define a related name constraint in the model, for the user field,

user = models.ForeignKey(User, related_name="my_objects")

Then, you can get from the user objects directly,

user = User.objects.get(username=username)
object_name = user.my_objects.get(slug__iexact=slug)

Also, using python default keywords for naming variables are strictly not recommended. "object" is a valid python keyword. Its just not a good practice.

wrdeman · Accepted Answer · 2017-05-15 09:50:06Z

0

Set unique=True on the model field object_name.

answered May 15, 2017 at 9:50

wrdeman

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2 Comments

lolz Over a year ago

but if i set it to unique then it won't allow me to have multiple objects with the same name.

Steffen Over a year ago

This won't work, because 'user1 can have a unique object name of (test) and user2 can also have a unique object name of (test).' He could use unique_together = (("user", "object_name"),). See docs.djangoproject.com/en/1.11/ref/models/options/…

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