Questions tagged [django-models]
For questions concerning use of the model class from the web framework Django.
38,983
questions
1184votes
24answers
388kviews
What is the difference between null=True and blank=True in Django?
When we add a database field in django we generally write:
models.CharField(max_length=100, null=True, blank=True)
The same is done with ForeignKey, DecimalField etc. What is the basic difference in ...
- 16.7k
843votes
17answers
536kviews
How do I do a not equal in Django queryset filtering?
In Django model QuerySets, I see that there is a __gt and __lt for comparative values, but is there a __ne or != (not equals)? I want to filter out using a not equals. For example, for
Model:
bool ...
- 42.1k
751votes
10answers
756kviews
How can I temporarily disable a foreign key constraint in MySQL?
Is it possible to temporarily disable constraints in MySQL?
I have two Django models, each with a foreign key to the other one. Deleting instances of a model returns an error because of the foreign ...
- 34.8k
712votes
13answers
227kviews
What is a "slug" in Django?
When I read Django code I often see in models what is called a "slug". I am not quite sure what this is, but I do know it has something to do with URLs. How and when is this slug-thing supposed to be ...
- 18.7k
611votes
11answers
372kviews
What does on_delete do on Django models?
I'm quite familiar with Django, but I recently noticed there exists an on_delete=models.CASCADE option with the models. I have searched for the documentation for the same, but I couldn't find anything ...
- 21.9k
544votes
9answers
419kviews
How to filter empty or NULL names in a QuerySet?
I have first_name, last_name & alias (optional) which I need to search for. So, I need a query to give me all the names that have an alias set.
Only if I could do:
Name.objects.filter(alias!="")
...
- 16.3k
521votes
11answers
161kviews
What's the difference between django OneToOneField and ForeignKey?
What's the difference between Django OneToOneField and ForeignKey?
- 7,895
511votes
15answers
281kviews
Extending the User model with custom fields in Django
What's the best way to extend the User model (bundled with Django's authentication app) with custom fields? I would also possibly like to use the email as the username (for authentication purposes).
...
- 16.8k
502votes
4answers
169kviews
How to define two fields "unique" as couple
Is there a way to define a couple of fields as unique in Django?
I have a table of volumes (of journals) and I don't want more then one volume number for the same journal.
class Volume(models.Model):...
- 12.2k
431votes
12answers
417kviews
How to query as GROUP BY in django?
I query a model:
Members.objects.all()
And it returns:
Eric, Salesman, X-Shop
Freddie, Manager, X2-Shop
Teddy, Salesman, X2-Shop
Sean, Manager, X2-Shop
What I want is to know the best Django way ...
- 33.3k
417votes
3answers
215kviews
What's the difference between select_related and prefetch_related in Django ORM?
In Django doc,
select_related() "follows" foreign-key relationships, selecting additional related-object data when it executes its query.
prefetch_related() does a separate lookup for each ...
- 15.2k
405votes
9answers
434kviews
How to delete a record in Django models?
I want to delete a particular record. Such as
delete from table_name where id = 1;
How can I do this in a django model?
- 9,773
385votes
16answers
276kviews
Convert Django Model object to dict with all of the fields intact
How does one convert a django Model object to a dict with all of its fields? All ideally includes foreign keys and fields with editable=False.
Let me elaborate. Let's say I have a django model like ...
- 30.5k
374votes
15answers
202kviews
Can "list_display" in a Django ModelAdmin display attributes of ForeignKey fields?
I have a Person model that has a foreign key relationship to Book, which has a number of fields, but I'm most concerned about author (a standard CharField).
With that being said, in my PersonAdmin ...
- 14k
367votes
5answers
281kviews
Django Model() vs Model.objects.create()
What it the difference between running two commands:
foo = FooModel()
and
bar = BarModel.objects.create()
Does the second one immediately create a BarModel in the database, while for FooModel, the ...
- 11.6k