CODEWITHSUNDEEP
pythondjangoexception
Tom
Tom

Reputation: 2661

how to catch the MultipleObjectsReturned error in django

Is it possible to catch the MultipleObjectsReturned error in Django?

I do a searchquery and if there are more than one objects I want that the first in the list will be taken so I tried this: 

try:
    Location.objects.get(name='Paul')
except MultipleObjectsReturned:
    Location.objects.get(name='Paul')[0]

However, it exists in the doc though

global variable MultipleObjectsReturned does not exist

Upvotes: 38

Views: 57387

Answers (5)

Hemant Yadav
Hemant Yadav

Reputation: 171

Use get when you know there is only one object that matches your query. If no items match the query, get() will raise a DoesNotExist exception. If multiple items matches the query, get() will raise a MultipleObjectsReturned exception. Use get() like this:

try:
  one_entry = Entry.objects.get(blog=2000)
except Entry.DoesNotExist:
  # query did not match to any item.
  pass
except Entry.MultipleObjectsReturned:
  # query matched multiple items.
  pass
else:
  # query matched to just one item
  print(one_entry)

Upvotes: 5

Mohammed Shareef C
Mohammed Shareef C

Reputation: 4050

Actually, even if we use MyModel.objects.get_or_create(...), there is still chances for creation of multiple instances due to race conditions. So, when we have to use MyModel.objects.get or MyModel.objects.get_or_create, we still have to expect return of multiple objects.

To handle this:

from django.core.exceptions import MultipleObjectsReturned

try:
    obj,is_created=MyModel.objects.get_or_create(....)
except MultipleObjectsReturned as e:
    # handle the case as you need here
    pass

Upvotes: 3

rofls
rofls

Reputation: 5115

Use a filter:

Location.objects.filter(name='Paul').first()

Or import the exception:

from django.core.exceptions import MultipleObjectsReturned
...
try:
    Location.objects.get(name='Paul')
except MultipleObjectsReturned:
    Location.objects.filter(name='Paul').first()

Upvotes: 61

Vaseem Ahmed Khan
Vaseem Ahmed Khan

Reputation: 805

This is more pythonic way to do it.

try:
    Location.objects.get(name='Paul')
except Location.MultipleObjectsReturned:
    Location.objects.filter(name='Paul')[0]

Upvotes: 48

veggie1
veggie1

Reputation: 747

This isn't the best practice. You can technically do this without using exceptions. Did you intend to use Location and Car in this example?

You can do this:

Location.objects.filter(name='Paul').order_by('id').first()

I strongly suggest you read the Django QuerySet API reference.

https://docs.djangoproject.com/en/1.8/ref/models/querysets/

To answer your question about where the exception exists -- you can always access these QuerySet exceptions on the model itself. E.g. Location.DoesNotExist and Location.MultipleObjectsReturned. You don't need to import them if you already have the model imported.

Upvotes: 13

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