83 lines
3.4 KiB
Python
83 lines
3.4 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.utils.functional import curry
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from django.utils.importlib import import_module
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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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def load_backend(backend_name):
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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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return import_module('.base', 'django.db.backends.%s' % 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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return import_module('.base', backend_name)
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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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try:
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available_backends = [f for f in os.listdir(backend_dir)
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if os.path.isdir(os.path.join(backend_dir, f))
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and not f.startswith('.')]
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except EnvironmentError:
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available_backends = []
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available_backends.sort()
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if backend_name not in available_backends:
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error_msg = "%r isn't an available database backend. Available options are: %s\nError was: %s" % \
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(backend_name, ", ".join(map(repr, available_backends)), e_user)
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raise ImproperlyConfigured(error_msg)
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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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backend = load_backend(settings.DATABASE_ENGINE)
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# `connection`, `DatabaseError` and `IntegrityError` are convenient aliases
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# for backend bits.
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# DatabaseWrapper.__init__() takes a dictionary, not a settings module, so
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# we manually create the dictionary from the settings, passing only the
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# settings that the database backends care about. Note that TIME_ZONE is used
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# by the PostgreSQL backends.
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connection = backend.DatabaseWrapper({
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'DATABASE_HOST': settings.DATABASE_HOST,
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'DATABASE_NAME': settings.DATABASE_NAME,
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'DATABASE_OPTIONS': settings.DATABASE_OPTIONS,
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'DATABASE_PASSWORD': settings.DATABASE_PASSWORD,
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'DATABASE_PORT': settings.DATABASE_PORT,
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'DATABASE_USER': settings.DATABASE_USER,
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'TIME_ZONE': settings.TIME_ZONE,
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})
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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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def close_connection(**kwargs):
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connection.close()
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signals.request_finished.connect(close_connection)
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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(**kwargs):
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connection.queries = []
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signals.request_started.connect(reset_queries)
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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(**kwargs):
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from django.db import transaction
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try:
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transaction.rollback_unless_managed()
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except DatabaseError:
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pass
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signals.got_request_exception.connect(_rollback_on_exception)
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