Updating DAC Extension - acumatica

Question

I am trying to update some custom fields in a DAC extension via code, it is not saving the changes to the DB. The code works fine to retrieve the extension and data. What am I missing - do i have to somehow update the myLS with the extension (i thought it did that automatically)?
myLS = LineItemSerial.Select();
INItemLotSerialExt myext = myLS.GetExtension<INItemLotSerialExt>();
myext.UsrFrame1 = "xyz";
myext.UsrFrame2 = "zzz";
myext.UsrFrame3 = "yyy";
LineItemSerial.Update(myLS);
graph.Actions.PressSave();

Answer 1

You should say to cache of Acumatica that you want to update value:
LineItemSerial.Cache.SetValueExt(myLS , "UsrFrame1", "xyz");
LineItemSerial.Cache.SetValueExt(myLS , "UsrFrame2 ", "zzz");
LineItemSerial.Cache.SetStatus(myLS , PXEntryStatus.Modified);
LineItemSerial.Cache.Update(myLS);
LineItemSerial.Cache.IsDirty = true;
NB. LineItemSerial.Cache.IsDirty = true; for some cases can be omitted but in my experience it was often helpful.

Answer 2

INItemLotSerialExt myext = LineItemSerial.GetExtension<INItemLotSerialExt>(myLS); //if LineItemSerial is a view related to the DAC. I hope LineItemSerial is a public view defined in the graph as you are trying to save the changes when u press the save of graph.
OR
INItemLotSerialExt myext = PXCache<INItemLotSerial>.GetExtension<INItemLotSerialExt>(myLS);
Is'nt this the rite way to get the extension?
From documentation
GetExtension(object)
InventoryItem item = cache.Current as InventoryItem;
InventoryItemExtension itemExt =
cache.GetExtension<InventoryItemExtension>(item);
OR
GetExtension(Table)
The code below gets an extension data record corresponding to the given instance of the base data record.
InventoryItem item = cache.Current as InventoryItem;
InventoryItemExtension itemExt =
PXCache<InventoryItem>.GetExtension<InventoryItemExtension>(item);

Answer 3

Try something like this...
ContractExtension cExt = PXCache<PMProject>.GetExtension<ContractExtension>(project);
ARInvoiceEntry graph = PXGraph.CreateInstance<ARInvoiceEntry>();
graph.Document.Current = graph.Document.Search<ARInvoice.projectID, ARInvoice.docDate>(projectID.Value, invoiceDate.Value);
if(graph.Document.Current !=null)
{
ARInvoice i = graph.Document.Current;
i.InvoiceNbr = cExt.CustomerPO;
graph.Document.Update(i);
graph.Actions.PressSave();
}