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Fixed #5454: settings.DATABASE_BACKEND may now refer to an external p…

…ackage (i.e. one located outside the Django source. Thanks, George Vilches.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@6316 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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commit 07447a0f562c62f020f00ba1d5248c5de4c264ca 1 parent 201a6cc
@jacobian jacobian authored
Showing with 46 additions and 20 deletions.
  1. +38 −17 django/db/__init__.py
  2. +8 −3 docs/settings.txt
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55 django/db/__init__.py
@@ -1,6 +1,9 @@
+import os
from django.conf import settings
from django.core import signals
+from django.core.exceptions import ImproperlyConfigured
from django.dispatch import dispatcher
+from django.utils.functional import curry
__all__ = ('backend', 'connection', 'DatabaseError', 'IntegrityError')
@@ -8,25 +11,43 @@
settings.DATABASE_ENGINE = 'dummy'
try:
- backend = __import__('django.db.backends.%s.base' % settings.DATABASE_ENGINE, {}, {}, [''])
+ # Most of the time, the database backend will be one of the official
+ # backends that ships with Django, so look there first.
+ _import_path = 'django.db.backends.'
+ backend = __import__('%s%s.base' % (_import_path, settings.DATABASE_ENGINE), {}, {}, [''])
except ImportError, e:
- # The database backend wasn't found. Display a helpful error message
- # listing all possible database backends.
- from django.core.exceptions import ImproperlyConfigured
- import os
- backend_dir = os.path.join(__path__[0], 'backends')
- available_backends = [f for f in os.listdir(backend_dir) if not f.startswith('_') and not f.startswith('.') and not f.endswith('.py') and not f.endswith('.pyc')]
- available_backends.sort()
- if settings.DATABASE_ENGINE not in available_backends:
- raise ImproperlyConfigured, "%r isn't an available database backend. Available options are: %s" % \
- (settings.DATABASE_ENGINE, ", ".join(map(repr, available_backends)))
- else:
- raise # If there's some other error, this must be an error in Django itself.
-
-get_introspection_module = lambda: __import__('django.db.backends.%s.introspection' % settings.DATABASE_ENGINE, {}, {}, [''])
-get_creation_module = lambda: __import__('django.db.backends.%s.creation' % settings.DATABASE_ENGINE, {}, {}, [''])
-runshell = lambda: __import__('django.db.backends.%s.client' % settings.DATABASE_ENGINE, {}, {}, ['']).runshell()
+ # If the import failed, we might be looking for a database backend
+ # distributed external to Django. So we'll try that next.
+ try:
+ _import_path = ''
+ backend = __import__('%s.base' % settings.DATABASE_ENGINE, {}, {}, [''])
+ except ImportError, e_user:
+ # The database backend wasn't found. Display a helpful error message
+ # listing all possible (built-in) database backends.
+ backend_dir = os.path.join(__path__[0], 'backends')
+ available_backends = [f for f in os.listdir(backend_dir) if not f.startswith('_') and not f.startswith('.') and not f.endswith('.py') and not f.endswith('.pyc')]
+ available_backends.sort()
+ if settings.DATABASE_ENGINE not in available_backends:
+ raise ImproperlyConfigured, "%r isn't an available database backend. Available options are: %s" % \
+ (settings.DATABASE_ENGINE, ", ".join(map(repr, available_backends)))
+ else:
+ raise # If there's some other error, this must be an error in Django itself.
+def _import_database_module(import_path='', module_name=''):
+ """Lazyily import a database module when requested."""
+ return __import__('%s%s.%s' % (_import_path, settings.DATABASE_ENGINE, module_name), {}, {}, [''])
+
+# We don't want to import the introspect/creation modules unless
+# someone asks for 'em, so lazily load them on demmand.
+get_introspection_module = curry(_import_database_module, _import_path, 'introspection')
+get_creation_module = curry(_import_database_module, _import_path, 'creation')
+
+# We want runshell() to work the same way, but we have to treat it a
+# little differently (since it just runs instead of returning a module like
+# the above) and wrap the lazily-loaded runshell() method.
+runshell = lambda: _import_database_module(_import_path, "client").runshell()
+
+# Convenient aliases for backend bits.
connection = backend.DatabaseWrapper(**settings.DATABASE_OPTIONS)
DatabaseError = backend.DatabaseError
IntegrityError = backend.IntegrityError
View
11 docs/settings.txt
@@ -253,9 +253,14 @@ DATABASE_ENGINE
Default: ``''`` (Empty string)
-The database backend to use. Either ``'postgresql_psycopg2'``,
-``'postgresql'``, ``'mysql'``, ``'mysql_old'``, ``'sqlite3'``,
-``'oracle'``, or ``'ado_mssql'``.
+The database backend to use. The build-in database backends are
+``'postgresql_psycopg2'``, ``'postgresql'``, ``'mysql'``, ``'mysql_old'``,
+``'sqlite3'``, ``'oracle'``, or ``'ado_mssql'``.
+
+You can also use a database backend that doesn't ship with Django by
+setting ``DATABASE_ENGINE`` to a fully-qualified path (i.e.
+``mypackage.backends.whatever``). Writing a whole new database backend from
+scratch is left as an exercise to the reader.
DATABASE_HOST
-------------
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