os.environ raises keyerror(key) from none - python-3.x

Question

I am making a database gui program and I am experimenting on how to make the .db file in a different folder from the script. I am using python 3.7. Here is the function that I use:
def get_database_file():
dir_path = os.path.join(os.environ[''], 'test_database')
if not os.path.exists(dir_path):
os.makedirs(dir_path)
file_path = os.path.join(dir_path, 'test_database.db')
if not os.path.exists(file_path):
try:
conn = sqlite3.connect(file_path)
conn.execute("PRAGMA foreign_keys = 1")
except sqlite3.Error as err:
if conn:
conn.rollback() # reverse any changes before the commit
print("SQLite Error: %s" % err.args[0])
sys.exit(-1)
else:
createDatabase(file_path)
print("Finish database created")
finally:
if conn:
conn.close()
else:
return file_path
if os.stat(file_path) == 0:
print("Empty")
else:
print("Not Empty")
return file_path
When I put os.environ['APPDATA'], this function runs fine without any errors. But when I put os.environ['HOME'], it shows this error message:
Traceback (most recent call last):
File "C:/Users/jojot/PycharmProjects/CreateDatabase/gui_database.py", line 4214, in <module>
database_file = get_database_file()
File "C:/Users/jojot/PycharmProjects/CreateDatabase/gui_database.py", line 4178, in get_database_file
dir_path = os.path.join(os.environ['HOME'], 'test_database')
File "C:\Users\jojot\AppData\Local\Programs\Python\Python37-32\lib\os.py", line 678, in __getitem__
raise KeyError(key) from None
KeyError: 'HOME'
I don't understand, what did I do wrong? Please help. Thank you.

Answer 1

It means that you haven't set the environment variable HOME.
If you want the program not to crash if you haven't set that variable you can use:
x = os.environ.get('HOME')
print(x) # None
instead of:
x = os.environ['HOME']
# raise KeyError(key) from None
# KeyError: 'HOME'