Agentry reload object collection not working properly

Question

Hello Experts.
I am quite new to Agentry Development and is really struggling with refreshing a local collection on the client used for a list display.
I am using a version 6.0.14 Agentry Server (stand-alone) and a version 6.0.38 ATE for testing the client.
I have created an item collection in the main object.
In a detail screen I have 2 fields for searching out the item values to be displayed.
When clicking an action button, an action is executed which deletes the content of the collection and afterwards filling the collection with proper values (from a complex table).
The filling part work perfectly and the first time it is called the collection is populated correctly and displayed in a listview control on a subsequent detail screen.
If I close the screen (and return to the search screen) and execute the action again the delete loop seems very unstable.
The delete loop is a subaction step which loops over the collection and calls a delete transaction for each record.
I have set the flag for 'Discarding pending transactions' meaning that added transactions will be removed from the transaction queue if a delete is subsequently issued for the same key.
I have tried:
- Looping over the collection (unconditionally) and then deleting every record.
   This turned out to only delete every second record from the collection, which caused an error in the loading step because now some of the records already existed.
- Then I have tried to make a loop while 'a condition is true'. Here I check that the collection is non-empty in which case I delete the first record.
   This actually seems to delete the entire collection (inspected in ATE). However when reloading the collection errors are issued stating that some objects are actually present. Sometimes a few objects seem to get stuck in the transaction queue with an empty key value on the header level, and these are also treated as existing in the collection.
- I have added the EmptySteplet in the update step of the transactions, with a 'Delete from client'. This means that when I do a transmit the entire transaction queue, for this object, is emptied.
  This is however not feasible, because I then need to make a transmit everytime, the user want to make a new search.
I am really stuck and unable to find a proper solution for this problem.
To me it looks really simple: I have a collection that I want to delete and reload with new values.
It should not be that complicated.
I hope someone has a suggestion for me.
Thank you and best regards,
Søren Hansen, Dong Energy, Denmark

Answer 1

Soren,
The ATE (Agentry Test Environment) is buggy at best.  Unfortunately this is the client that receives the least attention from the Agentry developers, even though it is the most important to those creating mobile applications with the platform.  The Edit to clear an empty collection should work fine, and probably does on normal clients.  Here is a solution to your last point about taking a while to send up the transactions.  To avoid the transaction queue filling up, there is another safe way to delete objects from a collection, just not as simple:
Create a sub-action step of type: Execute while rule is true
In your execute rule, check to make sure there is at least one object in the collection.  Use the TYPE function which acts as a boolean WHERE EXISTS check:
TYPE
     MyCollection -> First Object
The above will return Boolean "True" if there is at least one record in the collection, or "False" if not.
Then for the Action target, use: MyCollection -> First Object.
This will pass the first object in the collection to the action.
The tied-in action should run a delete transaction against whatever type of object resides in MyCollection.
Finish with a single Apply to commit the deletes in the parent action.
This will safely keep deleting objects until the rule returns false.  This is an alternative to looping over the collection as you tried previously.  That doesn't work as you found.  Trying to delete things out of the collection the outer loop is using causes problems.
Jason Latko - Senior Product Developer at SAP