Composite entity processing


I am trying to do some check in the post load method of an entity WMSItemArrivalJournalLineV2Entity which is part of composite entity WMSItemArrivalJournalV2Entity. However when I write WMSItemArrivalJournalLineV2Entity test = this; in the post load method. The vaule is blank. This normally works when importing an entity but is failing for composite entity. Can any one please suggest me any other approach. My requirement is as follows:

1. Based on a field value provided I need to do certain validation. If this validation fails then I need to throw an error at the staging

2. After the import process is completed and records are created for the journal I need to invoke Post functionality.

For point 2, I am using postTargetProcess(DMFDefinitionGroupExecution _dmfDefinitionGroupExecution) method in the the entity but it is not getting invoked.

Any pointers would be very helpful.

Thanks in advance