Adding a dependency to a batch task at runtime - batch-processing

Question

I have a batch job in AX 2012 R2 that runs, essentially iterating over a table and creating an instance of a class (that extends RunBaseBatch) that gets added as a task.
I also have some post processing items I need to do, after all the tasks have completed.
So far, the following is working:
while select stagingTable where stagingTable.OperationNo == params.paramOperationNo()
{
batchHeader = this.getCurrentBatchHeader();
batchTask = OperationTask::construct();
batchHeader.addRuntimeTask(batchTask,this.getCurrentBatchTask().RecId);
}
batchHeader.save();
postTask = PostProcessingTask::construct();
batchHeader.addRuntimeTask(postTask,this.getCurrentBatchTask().RecId);
batchHeader.addDependency(postTask,batchTask,BatchDependencyStatus::FinishedOrError);
batchHeader.save();
My thought is that this will add a dependency on the post process task to not start until we get Finished or Error on the last task added in the loop. What I get instead is an exception "The dependency could not be created because task '' does not exist."
I'm uncertain what I'm missing, as the tasks all get added executed successfully, it seems that just the dependency doesn't want to work.

Answer 1

Several things, where this code is being called matters. Is the code already in batch? Is the code calling in doBatch() before/after the super? etc.
You have a while-select, does this create multiple batch tasks? If it does, then you need to create a dependency on each batch task object. This is one problem I see. If your while-select statement only selects 1 record and adds one task, then the problem is something else, but you shouldn't do a while-select to select one record.
Also, you call batchHeader.save(); two times. I'd probably remove the first call. I'd need to see what is instantiating your code.
Where you have this.getCurrentBatchTask().RecId, depending on if your code is in batch or not, try replacing that with BatchHeader::getCurrentBatchTask().RecId
And where you have batchHeader = this.getCurrentBatchHeader(); replace that with batchHeader = BatchHeader::getCurrentBatchHeader();
EDIT Try this code (fix whatever to make it compile)
BatchHeader batchHeader = BatchHeader::getCurrentBatchHeader();
Set set = new Set(Types::Class);
SetEnumerator se;
BatchTask batchTask;
PostTask postTask;
while select stagingTable where stagingTable.OperationNo == params.paramOperationNo()
{
batchTask = OperationTask::construct();
set.add(batchTask);
batchHeader.addRuntimeTask(batchTask,BatchHeader::getCurrentBatchTask().RecId);
}
// Create post task
postTask = PostProcessingTask::construct();
batchHeader.addRuntimeTask(postTask,BatchHeader::getCurrentBatchTask().RecId);
// Create dependencies
se = set.getEnumerator();
while (se.moveNext())
{
batchTask = se.current(); // Task to make dependent on
batchHeader.addDependency(postTask,batchTask,BatchDependencyStatus::FinishedOrError);
}
batchHeader.save();