difference between objects.create() and object.save() in django orm
PythonDjangoOrmPython Problem Overview
u = UserDetails.objects.create(first_name='jake',last_name='sullivan')
u.save()
UserDetails.objects.create() and u.save() both perform the same save() function. What is the difference? Is there any extra check or benefit in using create() vs save()?
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Python Solutions
Solution 1 - Python
The Django documentation says it is the same. It is just more convenient to make it on one line. You could make a save() on one line too, but it would be more verbose and less readable -- it is clear you are creating a new object with the create() method.
> ### create(**kwargs)
>
> A convenience method for creating an object and saving it all in one
> step. Thus:
>
> p = Person.objects.create(first_name="Bruce", last_name="Springsteen")
>
> and:
>
> p = Person(first_name="Bruce", last_name="Springsteen")
> p.save(force_insert=True)
>
> are equivalent.
>
> The force_insert parameter is documented elsewhere, but all it means
> is that a new object will always be created. Normally you won’t need
> to worry about this. However, if your model contains a manual primary
> key value that you set and if that value already exists in the
> database, a call to create() will fail with an IntegrityError since
> primary keys must be unique. Be prepared to handle the exception if
> you are using manual primary keys.
Solution 2 - Python
Similar question: https://stackoverflow.com/questions/26672077/django-model-vs-model-objects-create
The difference between Model() vs Model.objects.create() are summarized as below.
-
.save()perform internally as either INSERT or UPDATE object to db, while.objects.create()perform only INSERT object to db.Model.save()perform ....UPDATE → If the object’s primary key attribute is set to a value that evaluates to
TrueINSERT → If the object’s primary key attribute is not set or if the UPDATE didn’t update anything (e.g. if primary key is set to a value that doesn’t exist in the database).
-
If primary key attribute is set to a value then
Model.save()perform UPDATE butModel.objects.createraiseIntegrityError.eg.
models.py
class Subject(models.Model): subject_id = models.PositiveIntegerField(primary_key=True, db_column='subject_id') name = models.CharField(max_length=255) max_marks = models.PositiveIntegerField()1) Insert/Update to db with
Model.save()physics = Subject(subject_id=1, name='Physics', max_marks=100) physics.save() math = Subject(subject_id=1, name='Math', max_marks=50) # Case of update math.save()Output:
Subject.objects.all().values() <QuerySet [{'subject_id': 1, 'name': 'Math', 'max_marks': 50}]>2) Insert to db with
Model.objects.create()Subject.objects.create(subject_id=1, name='Chemistry', max_marks=100) IntegrityError: UNIQUE constraint failed: m****t.subject_idExplanation: Above
math.save()is case of update sincesubject_idis primary key andsubject_id=1exists django internally perform UPDATE, name Physics to Math and max_marks from 100 to 50 for this, butobjects.create() raise IntegrityError
Model.objects.create()not equivalent toModel.save()however same can be achieved withforce_insert=Trueparameter onsavemethod i.eModel.save(force_insert=True).
Model.save()returnNonewhereModel.objects.create()return model instance i.e.package_name.models.Model
Conclusion: Model.objects.create() internally do model initialization and perform save with force_insert=True.
source-code block of Model.objects.create()
def create(self, **kwargs):
"""
Create a new object with the given kwargs, saving it to the database
and returning the created object.
"""
obj = self.model(**kwargs)
self._for_write = True
obj.save(force_insert=True, using=self.db)
return obj
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Note: Above answer is from question.