I am declaring a method named add_to_cart(db, itemid, quantity). Whenever the method is called, it will look into the database for the session data. Session data contains a list of dictionaries. The purpose of this method is to create a new entry (dictionary) to the list or update the value of existing entry. Dictionary has the following keys: id, quantity
So far I have developed the following code. First of all after fetching the data from the database, I am matching the itemid with the dictionary key: 'id'. If the itemid does not match with any of the values of the dictionaries, then it will append a new dictionary to that list.
def add_to_cart(db, itemid, quantity):
# ......
row = cursor.fetchone()
if row is not None:
cart = json.loads(row['data'])
for dic in cart:
if str(dic.get("id")) == str(itemid):
dic['quantity'] = int(dic['quantity']) + quantity
data = json.dumps(cart)
# update the 'data' to the database
break
else:
if counter == len(cart):
item = {
'id': itemid,
'quantity': quantity
}
cart.append(item)
data = json.dumps(cart)
# update the 'data' to the database
break
Let the initial cart is like:
[{'id': '40', 'quantity': '2'}, {'id': '41', 'quantity': '5'}]
When I add 1 more of the item 40 to the cart, this should be like:
[{'id': '40', 'quantity': '3'}, {'id': '41', 'quantity': '5'}]
but I am getting :
[{'id': '40', 'quantity': '2'}, {'id': '41', 'quantity': '5'}, {'id': '40', 'quantity': '1'}]
You are adding a new dictionary to the list when you do cart.append(item), hence the list
[{'id': '40', 'quantity': '2'}, {'id': '41', 'quantity': '5'}]
ends up being
[{'id': '40', 'quantity': '2'}, {'id': '41', 'quantity': '5'}, {'id': '40', 'quantity': '1'}]
But you want to find the matching id in that list of dictionaries, and add to the quantity for that dictionary.
So the code will look like as below:
li = [{'id': '40', 'quantity': '2'}, {'id': '41', 'quantity': '5'}]
def add_elem(li, id, to_add):
#Iterate over the dictionaries
for item in li:
#If the id is found
if str(id) in item.values():
#Increment the quantity
item['quantity'] = str(int(item['quantity']) + to_add)
#Return the updated list
return li
print(add_elem(li, 40, 1))
The output will be
[{'id': '40', 'quantity': '3'}, {'id': '41', 'quantity': '5'}]
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