将参数传递给内部函数

Question

I wrote a little helper function to check how many movies I've added to my Flask-SQLAlchemy table in the last x hours/minutes/days:

#### Check how many movies were added in the last X (hours, minutes) Y (int)
def movies_added_last(x,y):
    current_time = dateconvert.arrow.utcnow().naive
    tf_hours_ago = current_time - timedelta(x = y)
    movies_within_the_last_tf = models.Movie.query.filter(models.Movie.timeadded > tf_hours_ago).count()
    print movies_within_the_last_tf

The goal is to be able to call it like so: (hours,24) or (minutes,10).

First of all, x is being recognized by timedelta() as an invalid attribute, as it only accepts arguments like hours , minutes , and weeks . timedelta() isn't treating x as a variable.

How can I make this function work?

EDIT

I should explain myself a bit better:

x is supposed to be the format argument that is passed to timedelta, and y is supposed to be the integer argument, so when I call movies_added_last(seconds, 60) I want movies added in the last 60 seconds, another way to say it is that I want the inner timedelta to evaluate as timedelta(seconds = 60) .

Answer 1

It looks to me like you want to use: timedelta(**{x:y}) rather than timedelta(x=y) .

With the latter, you're passing a default argument named x (with value y ) to timedelta . With the former, you're passing a default argument whose name is the value of x (still with a value of y ) to timedelta . eg

>>> from datetime import timedelta
>>> x = 'hours'
>>> timedelta(x=3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'x' is an invalid keyword argument for this function
>>> timedelta(**{x:3})
datetime.timedelta(0, 10800)

If you do this, then you'll call your function like so:

 movies_added_last('seconds', 60)
 movies_added_last('minutes', 20)
 # etc.

---

Other alternatives (which might be cleaner) are to unpack keyword arguments to your function:

def movies_added_last(**kwargs):
    current_time = dateconvert.arrow.utcnow().naive
    tf_hours_ago = current_time - timedelta(**kwargs)
    movies_within_the_last_tf = models.Movie.query.filter(models.Movie.timeadded > tf_hours_ago).count()
    print movies_within_the_last_tf

Now you can call this with any keyword arguments that you can use to call timedelta :

movies_added_last(seconds=60)
movies_added_last(minutes=20)
# etc.