Sorry for the spam but I just found a solution to my issue.  I just needed to set the DataValueChangedScope in the FieldSettings to AllAllocatedRecords.  I hope this helps others!

Hey Guys,

I apologize for bringing up an old issue but I'm experiencing this as well.  I'm using the cell value history to indicate edited cells.  When I bulk edit 19 + records, only the records in the scroll view log the value change in the history.  

As per your above suggestion, I expect my grid to have 100s of records so I tried setting RecordLoadMode="PreloadRecords" and running the following in my InitializeRecord handler to try and initialize each cell:

if (e.Record == null || !e.Record.IsDataRecord || e.Record as DataRecord == null) return;
(e.Record as DataRecord).Cells.ForEach(cell => {});

I'm not sure if this is what you meant by "Since the cells are also lazily allocated, you would want to handle the InitializeRecord event and simply index into the Cells collection of the e.Record for the Field on which you have enabled the history" but this is not working for me.

Using CellContainerGenerationMode="PreLoad" & RecordContainerGenerationMode="PreLoad" but affects my screen's performance (as expected).  Do you have any other suggestions?  

Florian,

I believe I am running into the same issue.  I'm basically allowing the user to input an equation that will change the value of every cell in a specified column.  Obviously this is an issue when one desires to use the cell value history because all of the CellValuePresenters will not be loaded if the grid contains more records than can be shown on the screen.

I have written custom code that will automatically scroll through the grid to allow each cell value presenter to load before I set the value on the cell.  The issue I'm having is that if RecordContainerGenerationMode is not set to "PreLoad", the cell value historys will not be saved.

Is that what you are experiencing?

Hello Andrew, and thank you very much for your very detailed and helpful response.

I am still running into what I think is a bug in the grid when handling history when not pre-alocating records and cells. I think that virtualization process doesn't reassign the proper cell history to the presenter when scrolling to a virtualized record.

I attached a sample app which is as barebones as possible. 

The goal : define styles that react to up/down signals from the dataset. I cannot modify the dataset in the real world, but in this test, I did add a 'PrevMarketPrice' to make the bug observable by the user.

When the app launches, press Toggle Update so the viewmodel spawns a thread that simulates market conditions. We're tracking the history for the MarketPrice field here. 

The price going up triggers a green background, going down is red. This works fine for the initial set of records. 

To observe the bug, while the update is running, please scroll down to the bottom of the grid.

You will observe that the cells have a color assigned to them when scrolling into view, but this color never changes. Setting a breakpoint in the history converter, you will see that the CellValuePresenter.ValueHistory collection is not accurate as it only contains the value contained in the cell when it first scrolled into view and is never updated. The converter then subsequently runs against this value and the current cell value, but the output isn't accurate as it then represents the tick variation since the record scrolled into view.

This is extremely strange, as the log output and breakpoints set in the grid's DataValueChanged event will show that the Cell's history (and not the CellValuePresenter's) contains the proper values.

I tested and reproduced this behaviour both under XP and Win7 64, and by using Fields and UnboundFields with any BindingRetention possible.

The bug dissappears when setting RecordContainerGenerationMode and  CellContainerGenerationMode to "PreLoad" 

Regards,

Florian