Question

people. I’m python newbie. I have two def functions as below under a class.

def add_item(self, itemID, itemlist):
    lines = []

    self.itemID = itemID
    self.itemlist = itemlist

    for line in self.itemID, itemlist:
        lines.append(line)

and

def get_keys(self):
    i = []
    i.append(self.itemID)
    return i 

If I do

example.add_item('abc', item list)
example.add_item('abcd', item list)
example.add_item('abce', item list)

then when I do

example.get_keys()

It should give:

['abc', 'abcd', 'abce']

but mine only gives the latest one that is ['abce'].

Can anyone please let me know how to fix?

Answer 1

If I understand correctly, you want to add several couple of key and item_list to your example, and be able to retrieve the keys you added so far ? The easiest is to store the keys and the itemlist in two lists

Assuming that you initialize your object as such

def __init__(self, *args, **kwargs):
   self.itemID = []
   self.itemlist = []
   ...

Now, your add_item can simplify in

def add_item(self, itemID, itemlist):
    self.itemID.append(itemID)
    self.itemlist.append(itemlist)

and your get_key is only:

def get_keys():
    return self.itemID

---

• Note that the get_key is exactly the one you have suggested, just simpler (no need to create a temporary list).

• When you do

  lines = []
  for line in self.itemID, itemlist:
      lines.append(line)
  

  line first takes the value self.itemID, then itemlist. Eventually, your lines is just [self.itemID, itemlist]. Probably not what you had in mind.