List comprehension with partial string match

Question

Trying to write a function to search a requests response converted into a list of dictionaries. Each user returned will have many attributes, but I need to find users, by display_name based on the query passed through the main function.

Currently getting an error:

if query in user['display_name']: TypeError: argument of type 'NoneType' is not iterable

Function Definition

def search_users(self, query, group='any'):
    # Returns list of dictionaries representing users
    users = self.get_all_users()

    for user in users:
        if query in user['display_name']:
            result_set.append(user)

Main function call

looker.search_users('steve')

Answer 1

just change the line :

if query in user['display_name']:

to

if query in user.get('display_name',''):

the above answer will not work if the key is present and its value in None so i updated my answer according to @tobias_k comment -

if query in (user['display_name'] or ''):

Answer 2

It would seem that at least one of your display_name values is None.

When you use the in keyword in that case, you're looking for something in None , which throws an exception.

Depending on how you wanted to handle that case, you could check if the value exists before trying to append.

for user in users:
        if user and user['display_name'] and query in user['display_name']:  # probably extract this check into a helper
            result_set.append(user)

I would extract the Boolean logic into a separate method:

def is_query_match(user, query):
    if user and user['d'] and query in user['d']:
        return True
    return False

So you could then use:

for user in users:
    if is_query_match(user, query):
        result_set.append(user)