Python: Assigning query results to nested dictionary keys

In a flask project, I am looping through two lists to execute queries. Items from each list are variables in the SQL statements. I want the results of each query assigned to a key in the results dict:

dict1 = {}
dict2 = {}

list1 = [0,1]
list2 = ['criteria1',  'criteria2', 'criteria3']

for item in list1:
    cur.execute(query_one(item))
    foo = cur.fetchall()
    dict1[item] = foo
    for criterion in list2:
        cur.execute(query_two(item, criterion)):
        bar = cur.fetchall()
        dict2[item][criterion] = bar

dict1 looks good, but the above gives me KeyError: 0 on dict2.

If I change the last bit to dict2[criterion] = bar
Then dict2 only contains results from the query from list1[1] – like so:
{[result3], [result4]}

I want dict2 to look something like:

{0: [results1], [results2], 1: [results3], [results4]}

Appreciate any help.

>Solution :

You have to create an empty dictionary in dict2[item] so you can assign to its keys.

dict1 = {}
dict2 = {}

list1 = [0,1]
list2 = ['criteria1',  'criteria2', 'criteria3']

for item in list1:
    cur.execute(query_one(item))
    foo = cur.fetchall()
    dict1[item] = foo 
    dict2[item] = {}
    for criterion in list2:
        cur.execute(query_two(item, criterion)):
        bar = cur.fetchall()
        dict2[item][criterion] = bar