Oracle backend won't connect if password contains '@'

[Shane Allgeier]

The Oracle backend won't connect if password contains '@'.

For example, using this DATABASES config in settings.py:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.oracle',
        'NAME': 'mydsn',
        'USER': 'valid_username',
        'PASSWORD': 'p@ssword',
        'HOST': '',
        'PORT': '',
    }
}

I get this traceback:

Unhandled exception in thread started by <function check_errors.<locals>.wrapper at 0x7fab58f99ae8>
Traceback (most recent call last):
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/base/base.py", line 216, in ensure_connection
    self.connect()
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/base/base.py", line 194, in connect
    self.connection = self.get_new_connection(conn_params)
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/oracle/base.py", line 208, in get_new_connection
    return Database.connect(self._connect_string(), **conn_params)
cx_Oracle.DatabaseError: ORA-12154: TNS:could not resolve the connect identifier specified

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/utils/autoreload.py", line 225, in wrapper
    fn(*args, **kwargs)
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/core/management/commands/runserver.py", line 123, in inner_run
    self.check_migrations()
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/core/management/base.py", line 427, in check_migrations
    executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS])
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/migrations/executor.py", line 18, in __init__
    self.loader = MigrationLoader(self.connection)
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/migrations/loader.py", line 49, in __init__
    self.build_graph()
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/migrations/loader.py", line 206, in build_graph
    self.applied_migrations = recorder.applied_migrations()
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 61, in applied_migrations
    if self.has_table():
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 44, in has_table
    return self.Migration._meta.db_table in self.connection.introspection.table_names(self.connection.cursor())
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/base/base.py", line 255, in cursor
    return self._cursor()
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/base/base.py", line 232, in _cursor
    self.ensure_connection()
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/base/base.py", line 216, in ensure_connection
    self.connect()
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/base/base.py", line 216, in ensure_connection
    self.connect()
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/base/base.py", line 194, in connect
    self.connection = self.get_new_connection(conn_params)
  File "/home/shane/.virtualenvs/django-rms/lib/python3.6/site-packages/django/db/backends/oracle/base.py", line 208, in get_new_connection
    return Database.connect(self._connect_string(), **conn_params)
django.db.utils.DatabaseError: ORA-12154: TNS:could not resolve the connect identifier specified

After delving into the Oracle backend, I realized that Django is calling the cx_Oracle.connect() function like so: (django/db/backends/oracle/base.py line 208)

Database.connect('valid_username/p@ssword@mydsn')

You can probably guess why cx_Oracle doesn't like this. As far as I can tell, there's no possible way to work around this bug without directly editing Django's (or cx_Oracle's) code.
The following connection method works just fine:

Database.connect('valid_username', 'p@ssword', 'mydsn')

I should also mention that there have been ​others that have this issue. In my case, the bureaucracy at my company won't allow me to choose my own password, so fixing Django is my only option.