Question

I want to update only one field in my model. However, I am getting an error.

This is my model:

class People(models.Model):
    name = models.CharField(max_length=100)
    lastname = models.CharField(max_length=100)

class Salary(models.Model):
    id_of_people=models.ForeignKey(People)
    salary = models.IntegerField(required=False)

In views.py

-When I try this one to update :

def update(request):
a=Salary.objects.get(id_of_people_id=1)
a.salary=500
Salary().save()

My Error says:

IntegrityError  at/update
salary.id_of_people_id may not be NULL

and traceback indicates:

Salary().save()

-When I try this one :

def update(request):
a=Salary.objects.get(id_of_people_id=1)
a.salary=500
Salary().save(save_fields=['salary'])

-I get this error:

save() got an unexpected keyword argument 'save_fields'

Can you please help me to update only one field in my table ?

Answer 1

In both of those cases you’ll want to call save on the model instance you’ve created, not the model class–that is, you should be saving a, not Salary:

a.salary=500
a.save()

When you do Salary().save(), what’s happening is that you create a brand new, empty model instance, and then try to commit that to the database, rather than committing the one that you had just modified.