id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
23514	Prevent database connection at PostGISOperations init time	Claude Paroz	nobody	"Currently, `PostGISOperations` does query the database during its init time (to check the spatial version). This should be avoided if possible (see use case in #17656), and should be doable by transforming some variables into properties.


{{{
Traceback (most recent call last):
  File ""manage.py"", line 12, in <module>
    execute_from_command_line(sys.argv)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/core/management/__init__.py"", line 385, in execute_from_command_line
    utility.execute()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/core/management/__init__.py"", line 354, in execute
    django.setup()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/__init__.py"", line 21, in setup
    apps.populate(settings.INSTALLED_APPS)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/apps/registry.py"", line 108, in populate
    app_config.import_models(all_models)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/apps/config.py"", line 197, in import_models
    self.models_module = import_module(models_module_name)
  File ""/usr/lib64/python2.7/importlib/__init__.py"", line 37, in import_module
    __import__(name)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/contrib/auth/models.py"", line 40, in <module>
    class Permission(models.Model):
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/models/base.py"", line 125, in __new__
    new_class.add_to_class('_meta', Options(meta, **kwargs))
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/models/base.py"", line 300, in add_to_class
    value.contribute_to_class(cls, name)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/models/options.py"", line 166, in contribute_to_class
    self.db_table = truncate_name(self.db_table, connection.ops.max_name_length())
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/__init__.py"", line 40, in __getattr__
    return getattr(connections[DEFAULT_DB_ALIAS], item)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/utils.py"", line 243, in __getitem__
    conn = backend.DatabaseWrapper(db, alias)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/contrib/gis/db/backends/postgis/base.py"", line 14, in __init__
    self.ops = PostGISOperations(self)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/contrib/gis/db/backends/postgis/operations.py"", line 166, in __init__
    if self.spatial_version < (1, 3, 4):
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/utils/functional.py"", line 55, in __get__
    res = instance.__dict__[self.func.__name__] = self.func(instance)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/contrib/gis/db/backends/postgis/operations.py"", line 260, in spatial_version
    vtup = self.postgis_version_tuple()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/contrib/gis/db/backends/postgis/operations.py"", line 434, in postgis_version_tuple
    version = self.postgis_lib_version()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/contrib/gis/db/backends/postgis/operations.py"", line 414, in postgis_lib_version
    return self._get_postgis_func('postgis_lib_version')
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/contrib/gis/db/backends/postgis/operations.py"", line 404, in _get_postgis_func
    with self.connection.temporary_connection() as cursor:
  File ""/usr/lib64/python2.7/contextlib.py"", line 17, in __enter__
    return self.gen.next()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/backends/__init__.py"", line 543, in temporary_connection
    cursor = self.cursor()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/backends/__init__.py"", line 165, in cursor
    cursor = self.make_debug_cursor(self._cursor())
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/backends/__init__.py"", line 138, in _cursor
    self.ensure_connection()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/backends/__init__.py"", line 133, in ensure_connection
    self.connect()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/utils.py"", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/backends/__init__.py"", line 133, in ensure_connection
    self.connect()
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/backends/__init__.py"", line 122, in connect
    self.connection = self.get_new_connection(conn_params)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/django/db/backends/postgresql_psycopg2/base.py"", line 134, in get_new_connection
    return Database.connect(**conn_params)
  File ""/home/matt/repos/uwncom/lib/python2.7/site-packages/psycopg2/__init__.py"", line 164, in connect
    conn = _connect(dsn, connection_factory=connection_factory, async=async)
django.db.utils.OperationalError: FATAL:  role ""234124323"" does not exist
}}}
"	Cleanup/optimization	new	GIS	dev	Normal				Accepted	0	0	0	0	1	0