The differences between Model() and Model.objects.create() are the following:
INSERT vs UPDATE
Model.save() does either INSERT or UPDATE of an object in a DB, while Model.objects.create() does only INSERT.
Model.save() does
UPDATE If the object’s primary key attribute is set to a value that evaluates to True
INSERT 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).
Existing primary key
If primary key attribute is set to a value and such primary key already exists, then Model.save() performs UPDATE, but Model.objects.create() raises IntegrityError.
Consider the following 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()
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()
Result:
Subject.objects.all().values()
<QuerySet [{'subject_id': 1, 'name': 'Math', 'max_marks': 50}]>
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_id
Explanation: In the example, math.save() does an UPDATE (changes name from Physics to Math, and max_marks from 100 to 50), because subject_id is a primary key and subject_id=1 already exists in the DB. But Subject.objects.create() raises IntegrityError, because, again the primary key subject_id with the value 1 already exists.
Forced insert
Model.save() can be made to behave as Model.objects.create() by using force_insert=True parameter: Model.save(force_insert=True).
Return value
Model.save() return None where Model.objects.create() return model instance i.e. package_name.models.Model
Conclusion: Model.objects.create() does model initialization and performs save() with force_insert=True.
Excerpt from the source code 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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