Django database query: How to get object by id?

Question

Django automatically creates an id field as primary key.

Now I need to get the object by this id.

object = Class.objects.filter()

How to write this filter?

score 288 · Accepted Answer · edited Aug 08 '16 at 23:40

288

If you want to get an object, using get() is more straightforward:

obj = Class.objects.get(pk=this_object_id)

edited Aug 08 '16 at 23:40

the Tin Man

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answered Nov 29 '10 at 02:18

iridescent

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FYI, `pk` is the preferred way to refer to the primary key for any model. The `id` field is only generated if the model author doesn't specifically designate a primary key. If the author *did* specify a primary key field that isn't named `id`, then there will not be an `id` field. – Craig Trader Nov 29 '10 at 04:18
Also FYI, `id` in a built-in function that returns the identity of an object. In a majority of cases referencing things by `id` will do the right thing e.g. `Class.objects.get(id=this_object_id)` work. But that's something to consider I guess. – Tom Jul 28 '16 at 20:45

score 26 · Answer 2 · answered Sep 28 '13 at 17:55

I got here for the same problem, but for a different reason:

Class.objects.get(id=1)

This code was raising an ImportError exception. What was confusing me was that the code below executed fine and returned a result set as expected:

Class.objects.all()

Tail of the traceback for the get() method:

File "django/db/models/loading.py", line 197, in get_models
    self._populate()
File "django/db/models/loading.py", line 72, in _populate
    self.load_app(app_name, True)
File "django/db/models/loading.py", line 94, in load_app
    app_module = import_module(app_name)
File "django/utils/importlib.py", line 35, in import_module
    __import__(name)
ImportError: No module named myapp

Reading the code inside Django's loading.py, I came to the conclusion that my settings.py had a bad path to my app which contains my Class model definition. All I had to do was correct the path to the app and the get() method executed fine.

Here is my settings.py with the corrected path:

INSTALLED_APPS = (
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    # ...
    'mywebproject.myapp',

)

All the confusion was caused because I am using Django's ORM as a standalone, so the namespace had to reflect that.

score 10 · Answer 3 · answered Jul 07 '20 at 20:58

10

You can also use get_object_or_404 django shortcut. It raises a 404 error if object is not found.

answered Jul 07 '20 at 20:58

Alvaro Rodriguez Scelza

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neat way to do unless one does not want to explicitly handle an object not found error – Saurabh Mahra Apr 05 '23 at 19:52

score 4 · Answer 4 · answered Oct 17 '19 at 02:11

4

You can use:

objects_all=Class.objects.filter(filter_condition="")

This will return a query set even if it gets one object. If you need exactly one object use:

obj=Class.objects.get(conditon="")

answered Oct 17 '19 at 02:11

Pratik Randad

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score 3 · Answer 5 · answered Oct 01 '19 at 17:31

3

You can also do:

obj = ClassModel.get_by_id(object_id)

This works, but there may I'm not sure if it's supported in Django 2.

answered Oct 01 '19 at 17:31

Anthony

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score 0 · Answer 6 · answered Sep 05 '20 at 14:07

In case you don't have some id, e.g., mysite.com/something/9182301, you can use get_object_or_404 importing by from django.shortcuts import get_object_or_404.

Use example:

def myFunc(request, my_pk):
    my_var = get_object_or_404(CLASS_NAME, pk=my_pk)

Django database query: How to get object by id?

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