Question

I have the following function:

def get_some_field(grouping_type_id):
    checkConnection() # establishes connection if none

    sql = "SELECT name FROM table_foo WHERE id=%d" % grouping_type_id
    results = conn.execute(sql)
    data = results.fetchone()
    return str(data['name']) if ((data) and ('name' in data)) else ''

If the database table is empty, I expect the function to return an empty string however, None is being returned instead.

Can anyone explain this behaviour?

Answer 1

This also returns 'None':

data = {'name': None}
result = str(data['name']) if ((data) and ('name' in data)) else ''

The problem is that (data) and ('name' in data) is truish, because data is not empty, and has 'name' key set (although set to None, you do not check it).

Change this line:

return str(data['name']) if ((data) and ('name' in data)) else ''

into this line:

return str(data.get('name') or '') if data else ''