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import sys
from ctypes.util import find_library
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.db.backends.sqlite3.base import (
Database, DatabaseWrapper as SQLiteDatabaseWrapper, SQLiteCursorWrapper,
)
from django.utils import six
from .client import SpatiaLiteClient
from .features import DatabaseFeatures
from .introspection import SpatiaLiteIntrospection
from .operations import SpatiaLiteOperations
from .schema import SpatialiteSchemaEditor
class DatabaseWrapper(SQLiteDatabaseWrapper):
SchemaEditorClass = SpatialiteSchemaEditor
# Classes instantiated in __init__().
client_class = SpatiaLiteClient
features_class = DatabaseFeatures
introspection_class = SpatiaLiteIntrospection
ops_class = SpatiaLiteOperations
def __init__(self, *args, **kwargs):
# Before we get too far, make sure pysqlite 2.5+ is installed.
if Database.version_info < (2, 5, 0):
raise ImproperlyConfigured('Only versions of pysqlite 2.5+ are '
'compatible with SpatiaLite and GeoDjango.')
# Trying to find the location of the SpatiaLite library.
# Here we are figuring out the path to the SpatiaLite library
# (`libspatialite`). If it's not in the system library path (e.g., it
# cannot be found by `ctypes.util.find_library`), then it may be set
# manually in the settings via the `SPATIALITE_LIBRARY_PATH` setting.
self.spatialite_lib = getattr(settings, 'SPATIALITE_LIBRARY_PATH',
'mod_spatialite')
if not self.spatialite_lib:
raise ImproperlyConfigured('Unable to locate the SpatiaLite library. '
'Make sure it is in your library path, or set '
'SPATIALITE_LIBRARY_PATH in your settings.'
)
super(DatabaseWrapper, self).__init__(*args, **kwargs)
def get_new_connection(self, conn_params):
conn = super(DatabaseWrapper, self).get_new_connection(conn_params)
# Enabling extension loading on the SQLite connection.
try:
conn.enable_load_extension(True)
except AttributeError:
raise ImproperlyConfigured(
'The pysqlite library does not support C extension loading. '
'Both SQLite and pysqlite must be configured to allow '
'the loading of extensions to use SpatiaLite.')
# Loading the SpatiaLite library extension on the connection, and returning
# the created cursor.
cur = conn.cursor(factory=SQLiteCursorWrapper)
try:
cur.execute("SELECT load_extension(%s)", (self.spatialite_lib,))
except Exception as msg:
new_msg = (
'Unable to load the SpatiaLite library extension '
'"%s" because: %s') % (self.spatialite_lib, msg)
six.reraise(ImproperlyConfigured, ImproperlyConfigured(new_msg), sys.exc_info()[2])
cur.close()
return conn
def prepare_database(self):
super(DatabaseWrapper, self).prepare_database()
# Check if spatial metadata have been initialized in the database
with self.cursor() as cursor:
cursor.execute("PRAGMA table_info(geometry_columns);")
if cursor.fetchall() == []:
arg = "1" if self.features.supports_initspatialmetadata_in_one_transaction else ""
cursor.execute("SELECT InitSpatialMetaData(%s)" % arg)
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