Accessing old values on client side

Data Abstract
1

Hi,

I have a situation whereby I need to keep track of the old values of fields on the client-side. I will retrieve a data table from the server but then need to somehow store or access the original value of a field (for each record) even once it’s been edited, but before the updates are sent to the server.

Are the original values stored somewhere I can get at them or, if not, how should I best achieve this?

2

What is the client app platform?

3

Delphi

4

You can get old values for changed records via table.Delta.Changes[i].OldValues array

5

Ah ok thanks I’ll look at that

6

Another question which I’ll ask here rather than starting a new thread…

Can I add an “extra” field to a datatable but have the streaming system ignore it? I want to add an extra field which will only be used client-side, displayed in a grid for the user to enter values into. This field won’t be in the schema or “known” to the server, I’ll do something else with the values entered into it.

If I add an additional field then I get a streaming error as the field count doesn’t match what’s returned from the database.

I guess I could open the table then add the field afterward at runtime but that’s clunky. Didn’t know if there was another way of doing this.

7

you can add any field with “LogChanged=False” to server schema. in this case, this field will be ignored by delta commands (insert/update/delete) and it will never sent to server from client-side

this field can be created like

SELECT
   ...,
   0 as MyField,
   "" as MyField2
FROM ...
8

Thanks I’ll give that a try