Is there a more elegant way to write this in Python?

Question

I want to append 'status' to the dict value indexed by 'update_fields' or add ['status'] as a value to kwargs indexed by 'update_fields' if that key isn't present.

kwargs.setdefault('update_fields', kwargs.get('update_fields', []).append('status'))

It's either this or about 3 lines of code, surely python can do better than this!

Answer 1

get and setdefault are essentially two methods of doing the same thing; putting them together is repeating yourself. The only difference between get and setdefault is that setdefault sets the value if the default doesn't exist. After that, they are identical semantically.

So this part:

kwargs.get('update_fields', [])

..is redundant. setdefault sets the default (and returns it, like get) if the dictionary doesn't have a value for that key yet, otherwise it just looks up the value associated with the key.

So all you need is:

kwargs.setdefault('update_fields', []).append('status')

Answer 2

You don't need the kwargs.get() bit, setdefault only sets the value if it's not already there, you can just write:

kwargs.setdefault('update_fields', []).append('status')