Bite 58. Using argparse to interface with a grocery cart

Below is a Groceries class with add/delete/show/search methods.

You as a Python Developer are asked to give your users a command line interface so they can use the program. In real life we would have a persistent DB behind it, but let's focus on practicing argparse.

If new to argparse you might want to check out Bites 56 and 57 first.

The program should work as shown here:

$ python groceries.py -h
usage: groceries.py [-h] [-a ADD ADD ADD | -d DELETE | -l | -s SEARCH]

optional arguments:
-h, --help            show this help message and exit
-a ADD ADD ADD, --add ADD ADD ADD
                        add item providing name (str), price (int), and
                        craving (bool)
-d DELETE, --delete DELETE
                        delete a product by name (str)
-l, --list            show items in cart
-s SEARCH, --search SEARCH
                        search items by name

$ python groceries.py -l
celery                         |   1
apples                         |   4
water                          |   2
coffee                         |   5
chicken                        |   6
pizza (craving)                |   4
------------------------------------
Total                          |  22

$ python groceries.py -s coffee
coffee                         |   5
------------------------------------
Total                          |   5

$ python groceries.py -a honey 5 False
celery                         |   1
apples                         |   4
water                          |   2
coffee                         |   5
chicken                        |   6
pizza (craving)                |   4
honey                          |   5
------------------------------------
Total                          |  27

$ python groceries.py -a chocolate 3 True
celery                         |   1
apples                         |   4
water                          |   2
coffee                         |   5
chicken                        |   6
pizza (craving)                |   4
chocolate (craving)            |   3
------------------------------------
Total                          |  25

$ python groceries.py -d chicken
celery                         |   1
apples                         |   4
water                          |   2
coffee                         |   5
pizza (craving)                |   4
------------------------------------
Total                          |  16

$ python groceries.py -d water
celery                         |   1
apples                         |   4
coffee                         |   5
chicken                        |   6
pizza (craving)                |   4
------------------------------------
Total                          |  20

$ python groceries.py -d none
Traceback (most recent call last):
File "groceries.py", line 101, in
    cart.delete(product)
File "groceries.py", line 53, in delete
    raise IndexError(f'{product} not in cart')
IndexError: none not in cart

$ python groceries.py -a bread
usage: groceries.py [-h] [-a ADD ADD ADD | -d DELETE | -l | -s SEARCH]
groceries.py: error: argument -a/--add: expected 3 arguments

$ python groceries.py -ad
usage: groceries.py [-h] [-a ADD ADD ADD | -d DELETE | -l | -s SEARCH]
groceries.py: error: argument -a/--add: expected 3 arguments

$ python groceries.py -dl
Traceback (most recent call last):
File "groceries.py", line 101, in
    cart.delete(product)
File "groceries.py", line 53, in delete
    raise IndexError(f'{product} not in cart')
IndexError: l not in cart

$ python groceries.py -l -s
usage: groceries.py [-h] [-a ADD ADD ADD | -d DELETE | -l | -s SEARCH]
groceries.py: error: argument -s/--search: expected 1 argument

$ python groceries.py -s -d
usage: groceries.py [-h] [-a ADD ADD ADD | -d DELETE | -l | -s SEARCH]
groceries.py: error: argument -s/--search: expected 1 argument

Good luck and keep calm and code in Python!