71 lines
3.3 KiB
Python
71 lines
3.3 KiB
Python
import os
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from django.conf import settings
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from django.core import signals
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from django.core.exceptions import ImproperlyConfigured
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from django.dispatch import dispatcher
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from django.utils.functional import curry
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__all__ = ('backend', 'connection', 'DatabaseError', 'IntegrityError')
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if not settings.DATABASE_ENGINE:
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settings.DATABASE_ENGINE = 'dummy'
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try:
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# Most of the time, the database backend will be one of the official
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# backends that ships with Django, so look there first.
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_import_path = 'django.db.backends.'
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backend = __import__('%s%s.base' % (_import_path, settings.DATABASE_ENGINE), {}, {}, [''])
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except ImportError, e:
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# If the import failed, we might be looking for a database backend
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# distributed external to Django. So we'll try that next.
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try:
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_import_path = ''
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backend = __import__('%s.base' % settings.DATABASE_ENGINE, {}, {}, [''])
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except ImportError, e_user:
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# The database backend wasn't found. Display a helpful error message
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# listing all possible (built-in) database backends.
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backend_dir = os.path.join(__path__[0], 'backends')
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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')]
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available_backends.sort()
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if settings.DATABASE_ENGINE not in available_backends:
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raise ImproperlyConfigured, "%r isn't an available database backend. Available options are: %s" % \
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(settings.DATABASE_ENGINE, ", ".join(map(repr, available_backends)))
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else:
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raise # If there's some other error, this must be an error in Django itself.
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def _import_database_module(import_path='', module_name=''):
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"""Lazyily import a database module when requested."""
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return __import__('%s%s.%s' % (_import_path, settings.DATABASE_ENGINE, module_name), {}, {}, [''])
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# We don't want to import the introspect/creation modules unless
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# someone asks for 'em, so lazily load them on demmand.
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get_introspection_module = curry(_import_database_module, _import_path, 'introspection')
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get_creation_module = curry(_import_database_module, _import_path, 'creation')
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# We want runshell() to work the same way, but we have to treat it a
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# little differently (since it just runs instead of returning a module like
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# the above) and wrap the lazily-loaded runshell() method.
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runshell = lambda: _import_database_module(_import_path, "client").runshell()
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# Convenient aliases for backend bits.
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connection = backend.DatabaseWrapper(**settings.DATABASE_OPTIONS)
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DatabaseError = backend.DatabaseError
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IntegrityError = backend.IntegrityError
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# Register an event that closes the database connection
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# when a Django request is finished.
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dispatcher.connect(connection.close, signal=signals.request_finished)
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# Register an event that resets connection.queries
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# when a Django request is started.
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def reset_queries():
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connection.queries = []
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dispatcher.connect(reset_queries, signal=signals.request_started)
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# Register an event that rolls back the connection
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# when a Django request has an exception.
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def _rollback_on_exception():
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from django.db import transaction
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transaction.rollback_unless_managed()
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dispatcher.connect(_rollback_on_exception, signal=signals.got_request_exception)
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