How to use the psycopg2.DatabaseError function in psycopg2

cursor_mock.execute.side_effect = None
        conn = server.postgres.connect()
        pg_connect_mock.assert_called_with("valid conninfo")
        assert conn is conn_mock

        # call again and make sure it returns the cached connection
        pg_connect_mock.reset_mock()

        new_conn = server.postgres.connect()

        assert new_conn is conn_mock
        assert not pg_connect_mock.called

        # call again with a broken connection
        pg_connect_mock.reset_mock()
        conn_mock.cursor.side_effect = [psycopg2.DatabaseError, cursor_mock]

        new_conn = server.postgres.connect()

        assert new_conn is conn_mock
        pg_connect_mock.assert_called_with("valid conninfo")

        # close it
        pg_connect_mock.reset_mock()
        conn_mock.cursor.side_effect = None
        conn_mock.closed = False

        server.postgres.close()

        assert conn_mock.close.called

        # close it with an already closed connection

def test_relvar_delete_missing(self):
        "Attempt to delete a tuple that has been deleted since it was fetched"
        self.insert_one()
        keytuple = self.relvar.key_tuple(1)
        currtuple = self.relvar.get_one(keytuple)
        self.delete_one(1)
        with pytest.raises(DatabaseError):
            self.relvar.delete_one(currtuple, keytuple)

for bank_account in bank_accounts:
            get_paged_data_and_load(cursor,'bank_transactions','bank_account=' + bank_account["url"])
        #    get_paged_data_and_load(cursor, 'bank_transaction_explanations','bank_account=' + bank_account["url"])
        
        get_paged_data_and_load(cursor, 'bills')
        get_paged_data_and_load(cursor, 'contacts')
        get_paged_data_and_load(cursor, 'expenses')
        get_paged_data_and_load(cursor, 'invoices')
        get_paged_data_and_load(cursor, 'projects')
        get_paged_data_and_load(cursor, 'users')
        
        get_csv_and_load(cursor, "server_costs", ["project_name","value"])
    
        connection.commit()
        
    except psycopg2.DatabaseError, e:
        print 'Error %s' % e    
        sys.exit(1)
    
    
    finally:
    
        if connection:
            connection.close()
    print "All done."

user=_options.get("user"),
                password=_options.get("passwd"),
                database=_options.get("db"),
                port=_options.get("port"),
            )

        except psycopg2.OperationalError as exc:
            raise salt.exceptions.SaltMasterError(
                "postgres returner could not connect to database: {exc}".format(exc=exc)
            )

        cursor = conn.cursor()

        try:
            yield cursor
        except psycopg2.DatabaseError as err:
            error = err.args
            sys.stderr.write(str(error))
            raise err
        finally:
            conn.close()

def execute(self, query, args=None):
        try:
            return self.cursor.execute(query, args)
        except Database.IntegrityError, e:
            raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]
        except Database.DatabaseError, e:
            raise utils.DatabaseError, utils.DatabaseError(*tuple(e)), sys.exc_info()[2]

def _increase_rank(self, field):
        if self.ids and field in ['customer_rank', 'supplier_rank']:
            try:
                with self.env.cr.savepoint():
                    query = sql.SQL("""
                        SELECT {field} FROM res_partner WHERE ID IN %(partner_ids)s FOR UPDATE NOWAIT;
                        UPDATE res_partner SET {field} = {field} + 1
                        WHERE id IN %(partner_ids)s
                    """).format(field=sql.Identifier(field))
                    self.env.cr.execute(query, {'partner_ids': tuple(self.ids)})
                    for partner in self:
                        self.env.cache.remove(partner, partner._fields[field])
            except DatabaseError as e:
                if e.pgcode == '55P03':
                    _logger.debug('Another transaction already locked partner rows. Cannot update partner ranks.')
                else:
                    raise e

def __init__(self, *args, **kwargs):
        super(Postgres, self).__init__(*args, **kwargs)

        self._current_cursor = None

        dbname = kwargs.pop('db', None) or os.environ.get('PGDATABASE')
        try:
            self.conn = psycopg2.connect(dbname=dbname, **kwargs)
        except psycopg2.DatabaseError as e:
            raise BackendError("Error connecting to Postgresql DB: {}"
                               .format(e))

        # authorize uuids objects in queries
        psycopg2.extras.register_uuid()
        # authorize dicts objects for hstore in queries
        try:
            psycopg2.extras.register_hstore(self.conn)
        except psycopg2.ProgrammingError:
            # this probably means that the hstore extension is not
            # installed in the db, no need to register it then
            pass

from django.db.backends.signals import connection_created
from django.db.backends.postgresql.operations import DatabaseOperations as PostgresqlDatabaseOperations
from django.db.backends.postgresql.client import DatabaseClient
from django.db.backends.postgresql.creation import DatabaseCreation
from django.db.backends.postgresql.version import get_version
from django.db.backends.postgresql_psycopg2.introspection import DatabaseIntrospection
from django.utils.safestring import SafeUnicode, SafeString

try:
    import psycopg2 as Database
    import psycopg2.extensions
except ImportError, e:
    from django.core.exceptions import ImproperlyConfigured
    raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)

DatabaseError = Database.DatabaseError
IntegrityError = Database.IntegrityError

psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
psycopg2.extensions.register_adapter(SafeString, psycopg2.extensions.QuotedString)
psycopg2.extensions.register_adapter(SafeUnicode, psycopg2.extensions.QuotedString)

class CursorWrapper(object):
    """
    A thin wrapper around psycopg2's normal cursor class so that we can catch
    particular exception instances and reraise them with the right types.
    """

    def __init__(self, cursor):
        self.cursor = cursor

    def execute(self, query, args=None):

def drop_repslot(self, slot_name):
        """
        Drop a physical replication slot using the streaming connection
        :param str slot_name: Replication slot name
        """
        cursor = self._cursor()
        try:
            # In the following query, the slot name is directly passed
            # to the DROP_REPLICATION_SLOT command, without any
            # quoting. This is a characteristic of the streaming
            # connection, otherwise if will fail with a generic
            # "syntax error"
            cursor.execute('DROP_REPLICATION_SLOT %s' % slot_name)
            _logger.info("Replication slot '%s' successfully dropped",
                         slot_name)
        except psycopg2.DatabaseError as exc:
            if exc.pgcode == UNDEFINED_OBJECT:
                # A replication slot with the that name does not exist
                raise PostgresInvalidReplicationSlot()
            if exc.pgcode == OBJECT_IN_USE:
                # The replication slot is still in use
                raise PostgresReplicationSlotInUse()
            else:
                raise PostgresException(force_str(exc).strip())