Athena Developer Guide

Athena Chapter 8 StoreGate - the event data access model Version/Issue: 2.0.0
• By providing a key, in which case there will be a unique match. Note that a keyed access is
possible only if you recorded theDataObject with a key. Since two DataObjects of the same
type cannot have the same key, you are assured of a unique DataObject (provided of course it
exists).
• You can ask for a list of DataObjects of a given type. You will be returned a begin and end
iterator over all the DataObjects of that type (whether or not it was recorded with a key).
For each of these three modes you have the option to require const access to the retrieved objects or non
constant access. In the latter case, if the DataObject has already been locked, as it will normally be the
case, the retrieve operation will not return the locked object (and will fail if no unlocked matching
objects are available).
8.6.1 Retrieving DataObjects without a key
In the execute method of ReadData, get the last MyDataObj recorded in the TDS (recall that we
recorded three MyDataObj in TDS, one with a key). The example shown in Listing 8.9 will retrieve the
last of the three MyDataObj from the TDS:
Listing 8.9 Retrieve a DataObject without a key
const DataHandle dhandle;
StatusCode sc = storeGateSvc()->retrieve(dhandle); [1]
if (sc.isFailure())
{
log