django passing arguments based on value

Question

I have defined optional variables in my django model. In my view, I might have those values or they might be None. I want to create that object without worrying about sending a None argument to the django model.

For example, Book object has a title, but publisher is optional.

right now in my view I'm doing something like

if publisher is None:
    Book.objects.create(title=title)
else:
    Book.objects.create(title=title, publisher=publisher)

Now this isn't manageable if there are multiple optional fields. What's the solution?

falsetru · Accepted Answer · 2014-08-16T08:54:17.757

0

How about using ** operator:

attrs = {'title': title}
if publisher is not None:
    attrs['publisher'] = publisher
Book.objects.create(**attrs)

UPDATE alternative - using Model.save:

book = Book(title='title')
if publisher is not None:
    book.publisher = publisher
book.save()

edited Aug 16 '14 at 08:54

answered Aug 16 '14 at 07:50

falsetru

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score 0 · Answer 2 · edited May 23 '17 at 11:57

0

Take a look at this:

Call a function with argument list in python

Basically create an array like args and then pass it in as *args to the method required.

You can also do something similar with **kwargs. Take a look at this:

Passing a list of kwargs?

edited May 23 '17 at 11:57

Community

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answered Aug 16 '14 at 08:17

KVISH

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`Model.objects.create` accept keyword arguments only. – falsetru Aug 16 '14 at 08:41

score 0 · Answer 3 · answered Aug 16 '14 at 09:22

Branching off the other answers... try this

def make_book(**kwargs):
    query = {key: value for key, value in kwargs.items() if value}
    Book.objects.create(**query)

I suggest declaring this as a method on your models manager so that you can quickly make instances where ever you need them like

Book.objects.make_book(title="The Title",publisher=None)

django passing arguments based on value

3 Answers3