add more values to a key python

Question

i would like to add this:

{
   "Category": "Fruit"
}

to this:

{
   "Category": "Vegetable"
{

so I can have:

"Name": "Menu1",
"Categories":[
    {
       "Category": "Fruit"
    {
    }
       "Category": "Vegetable"
    {
   ]

I'm creating a list of dicts and sometimes I can have 2 dicts with the same key["Name"] and i would like to to avoid having the two dicts with the same name separated. Currently I'm doing this to check if the "Name" already exists and if not create it and add it to the list:

if len(List) != 0: #checking if the list has something
   for x in List:
       if menu['Name'] == x['Name']:
          menu['Category'].append(Category) #if exist add data to the existing one
          break
       else:    
          List.append(menu) #if doesn't exist add it
          break
else:
   List.append(menu) #if is empty add an item

In Python empty lists are falsey you if List: is equivalent to if len(List) != 0: — sphennings
– sphennings, Commented Nov 5, 2020 at 19:55
If you break in both if and else, you only process the first element of List, so there's no reason to loop. — Barmar
– Barmar, Commented Nov 5, 2020 at 19:58
Maybe the first else: should be unindented so it's on the for loop, not if. — Barmar
– Barmar, Commented Nov 5, 2020 at 19:58

Barmar · Accepted Answer · 2020-11-05 20:03:25Z

1

You should be appending to x['Category'], not an unnamed list that contains the string 'Category'.

The else: block that adds the name should be on the for loop. This will execute if the loop ends normally instead of from break, which means the name wasn't found.

There's no need to check the length of List first. If it's empty, the loop will end normally and the else: block will execute.

for x in List:
    if menu['Name'] == x['Name']:
        x['Category'].append(Category) #if exist add data to the existing one
        break
else:    
    List.append(menu) #if doesn't exist add it

answered Nov 5, 2020 at 20:03

Barmar

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1 Comment

Joaquín Over a year ago

thanks for your answer! it helped me a lot resolving the problem but i had to change it a bit

Joaquín · Accepted Answer · 2020-11-07 05:37:59Z

0

So what I did was this:

for item in my_list:
    if item['Name'] == menu['Name']: #Exist in list
        print('Exist')
        var = []
        var.append({'Category': Category})
        x['Categories'] += var
        cod = []
        cod.append({'Code': code})
        x['Codes'] += cod
        break
else:
    my_list.append(menu) #doesn't exist
    print('not matched')

edited Nov 7, 2020 at 5:37

answered Nov 7, 2020 at 3:12

Joaquín

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4 Comments

Barmar Over a year ago

How does this add another category to the Categories list?

Barmar Over a year ago

That's the same as x['Categories'].append({'Category': Category}). There's no need to create another list.

Barmar Over a year ago

In my answer I assumed that Category was a dictionary like {'Category': "Fruit"}, not a string.

Joaquín Over a year ago

it wasn't working for me:( when i was using .append(something) that something was overwriting the previous value

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