BUG: omero.gateway getObject should raise an error while non of the args are set

[atarkowska]

Traceback (most recent call last):
  File "/Users/ola/Dev/omero/dist/lib/python/omeroweb/webadmin/tests/unittests.py", line 377, in test_createGroupsWithNonASCII
    group = conn.getObject("ExperimenterGroup", gid)
  File "/Users/ola/Dev/omero/dist/lib/python/omero/gateway/__init__.py", line 2498, in getObject
    result = self.getQueryService().findByQuery(query, params, self.CONFIG['SERVICE_OPTS'])
  File "/Users/ola/Dev/omero/dist/lib/python/omero/gateway/__init__.py", line 3267, in __call__
    return self.handle_exception(e, *args, **kwargs)
  File "/Users/ola/Dev/omero/dist/lib/python/omeroweb/webclient/webclient_gateway.py", line 1822, in handle_exception
    e, *args, **kwargs)
  File "/Users/ola/Dev/omero/dist/lib/python/omero/gateway/__init__.py", line 3264, in __call__
    return self.f(*args, **kwargs)
  File "/Users/ola/Dev/omero/dist/lib/python/omero_api_IQuery_ice.py", line 133, in findByQuery
    return _M_omero.api.IQuery._op_findByQuery.invoke(self, ((query, params), _ctx))
ApiUsageException: exception ::omero::ApiUsageException
{
    serverStackTrace = ome.conditions.ApiUsageException: Query named:

	select distinct obj from ExperimenterGroup as obj left outer join fetch obj.groupExperimenterMap as map left outer join fetch map.child e

has returned more than one Object
findBy methods must return a single value.
Please try findAllBy methods for queries which return Lists.

The error is misleading

[atarkowska]

In order to make the error more clear we could use findAllByQuery and then check if there is more then 1 results.

if len(result) > 1:
    raise AttributeError("getObject methods has returned more than one Object but must return a single value. Please try getObjects methods for queries which return Lists.")

method also doesn't contain return statement for no results.

[wmoore]

See #5168. We deliberately use findByQuery so that if I do getObject("Image") I don't load all Images to the client. The server has this checking functionality specifically for this use case. If you want to catch the server's exception at the BlitzGateway? and provide a nicer error message, that might be a nicer way to go, although I think that the server's error message is quite informative.

[jburel]

Moved from sprint 2012-06-05 (16)

[atarkowska]

As there are various pros and cons this ticket is invalid