[Python-modules-team] Bug#910240: python3-django: GeoDjango incorrectly initialize spatialite (Error: /usr/lib/x86_64-linux-gnu/mod_spatialite.so: undefined symbol: sqlite3_spatialite_init)

[Petter Reinholdtsen]

Package: python3-django
Version: 1:1.10.7-2

Today I decided to test GeoDjango, and set up a simple project using
spatialite.  But loading the spatialite database backend would fail like
this:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/django/contrib/gis/db/backends/spatialite/base.py", line 59, in get_new_connection
    cur.execute("SELECT load_extension(%s)", (self.spatialite_lib,))
  File "/usr/lib/python3/dist-packages/django/db/backends/sqlite3/base.py", line 337, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: /usr/lib/x86_64-linux-gnu/libspatialite.so.7: undefined symbol: sqlite3_spatialite_init

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "./manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/lib/python3/dist-packages/django/core/management/__init__.py", line 367, in execute_from_command_line
    utility.execute()
  File "/usr/lib/python3/dist-packages/django/core/management/__init__.py", line 359, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/lib/python3/dist-packages/django/core/management/base.py", line 294, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/lib/python3/dist-packages/django/core/management/base.py", line 345, in execute
    output = self.handle(*args, **options)
  File "/usr/lib/python3/dist-packages/django/core/management/commands/makemigrations.py", line 109, in handle
    loader.check_consistent_history(connection, fake_initial=True)
  File "/usr/lib/python3/dist-packages/django/db/migrations/loader.py", line 277, in check_consistent_history
    applied = recorder.applied_migrations()
  File "/usr/lib/python3/dist-packages/django/db/migrations/recorder.py", line 65, in applied_migrations
    self.ensure_schema()
  File "/usr/lib/python3/dist-packages/django/db/migrations/recorder.py", line 52, in ensure_schema
    if self.Migration._meta.db_table in self.connection.introspection.table_names(self.connection.cursor()):
  File "/usr/lib/python3/dist-packages/django/db/backends/base/base.py", line 231, in cursor
    cursor = self.make_debug_cursor(self._cursor())
  File "/usr/lib/python3/dist-packages/django/db/backends/base/base.py", line 204, in _cursor
    self.ensure_connection()
  File "/usr/lib/python3/dist-packages/django/db/backends/base/base.py", line 199, in ensure_connection
    self.connect()
  File "/usr/lib/python3/dist-packages/django/db/backends/base/base.py", line 171, in connect
    self.connection = self.get_new_connection(conn_params)
  File "/usr/lib/python3/dist-packages/django/contrib/gis/db/backends/spatialite/base.py", line 64, in get_new_connection
    six.reraise(ImproperlyConfigured, ImproperlyConfigured(new_msg), sys.exc_info()[2])
  File "/usr/lib/python3/dist-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/usr/lib/python3/dist-packages/django/contrib/gis/db/backends/spatialite/base.py", line 59, in get_new_connection
    cur.execute("SELECT load_extension(%s)", (self.spatialite_lib,))
  File "/usr/lib/python3/dist-packages/django/db/backends/sqlite3/base.py", line 337, in execute
    return Database.Cursor.execute(self, query, params)
django.core.exceptions.ImproperlyConfigured: Unable to load the SpatiaLite library extension "libspatialite.so.7" because: /usr/lib/x86_64-linux-gnu/libspatialite.so.7: undefined symbol: sqlite3_spatialite_init

After asking for help om #debian-gis and reading the source of
/usr/lib/python3/dist-packages/django/contrib/gis/db/backends/spatialite/base.py,
I discovered a workaround is to add this line to settings.py:

  SPATIALITE_LIBRARY_PATH = 'mod_spatialite'

According to sebastic on #debian-gis, the way to load spatialite changed
in version 4.2, and now the correct way to load the library is to use
"SELECT load_extension('mod_spatialite');", while the GeoDjango database
backend try to load it using the full path to the library file, which
for some reason is no longer working.

-- 
Happy hacking
Petter Reinholdtsen