How do I properly condense this Python IF statement?

Question

I am pretty new to Python, and trying to find a better way to code this. There has to be a way but just not sure how to do it.

The two queries are essentially the same, so there has to be a way to reduce. Is there a more efficient way to do this?

        if set_date is not None:

            if is_rejected != 'true':
                query = query\
                    .filter(createddate__lte=set_date) \
                    .car_statuses(CarTow.TOWED) \
                    .order_by('-createddate')
            else:
                query = query\
                    .filter(createddate__lte=set_date) \
                    .car_statuses(CarTow.TOWED,CarTow.CONFIRMED) \
                    .order_by('-createddate')

            return query

Sorry if this is a simple question, newbie here.

score 2 · Accepted Answer · answered Oct 01 '19 at 22:37

2

You can simplify by pulling the argument that differs into the if-statement & putting the common stuff outside.

if set_date is not None:
       if is_rejected != 'true':
             car_statuses = (CarTow.TOWED,)
       else:
             car_statuses = (CarTow.TOWED, CarTow.CONFIRMED)

       query = query\
           .filter(createddate__lte=set_date) \
           .car_statuses(*car_statuses) \
           .order_by('-createddate')
      return query

answered Oct 01 '19 at 22:37

rdas

18,048
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That worked great! Thank you. One point of clarity, what does the asterisk do? – SteveV Oct 01 '19 at 23:02
Tuple unpacking: https://pythontips.com/2013/08/04/args-and-kwargs-in-python-explained/comment-page-1/ – rdas Oct 01 '19 at 23:05

score 2 · Answer 2 · answered Oct 01 '19 at 23:04

2

You can use ternary logic to add the tuples.

query = (
    query
    .filter(createddate__lte = set_date) 
    .car_statuses((CarTow.TOWED,) + ((CarTow.CONFIRMED,) if is_rejected == 'true' else ()) 
    .order_by('-createddate')
)

answered Oct 01 '19 at 23:04

Alexander

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184

score 1 · Answer 3 · answered Oct 01 '19 at 22:59

You probably want to replace this:

if set_date is not None:

with this:

if set_date:

Take a look at how Python evaluates the if conditional: Truth Value Testing (pydocs)

Here are most of the built-in objects considered false: constants defined to be false: None and False. zero of any numeric type: 0, 0.0, 0j, Decimal(0), Fraction(0, 1) empty sequences and collections: '', (), [], {}, set(), range(0)

Also, 'is' can give some strange results, it's really for determining if two labels reference the same object or not. Understanding Python's is operator

Ok, good to know. Removed the "is" statement. Thanks for the link — SteveV, Oct 01 '19 at 23:12

How do I properly condense this Python IF statement?

3 Answers3