Extending DaStronglyTyped interface for table

Data Abstract
1

is there a way to extend an IMyTable DA interface so i can define own methods on it?
like a Class Helper for Interfaces?
i know i can get a hold of the DataTable … but that requires casting etc…
so i wonder if there is an elegant way around it which i do not know about…

2

Hi,

You can create a descendant of your datatable rule, register it and specify as table.BusinessRulesID.

I’ve attached outdated DA4 sample with similar functionality: Strongly Typed.zip (55.3 KB):

unit uBizCustomersClient;

{
  This unit contains the business rules handlers for the client application.

  The simplest possible implementation just overrides the methods inherited
  from TDADataTableRules (i.e. AfterInsert, BeforePost).

  More sophisticated ones instead add additional behaviour and even make it accessible
  from outside units (i.e. a form or a data module hosting a TDADataTable).

  TBizCustomersClientRules shows an example of both possibilities by overriding a few event
  handlers and adding support for the interface IAdvancedCustomer.

  Adding interfaces like IAdvancedCustomer is not required to implement extra functionality that is
  only accessed in the context of a business rule class/unit. You obviously can add any method you want to
  classes like TBizCustomersClientRules and reference them from other methods in order to make them
  more "object oriented" (see DummTest below).
  But when you need to access this functionality from the outside world you need to define an
  "access contract" via an interface. You can then treat TDADataTables as IAdvancedCustomer (or
  whatever other interface you decide to create) by simply using the VCL function Supports.
  See an example of this in the unit fClientForm.pas, method bCheckBalanceClick

  Note: TDADataTable also allows you to access the instance of TBizCustomersClientRules via the
        property BusinessRules. You could also type cast that property to TBizCustomersClientRules but
        in general, the interface approach is cleaner and more elegant.
}

note: this sample may require manual changes for compiling in DA10.

3

ah so basically introducing an inherited interface which has the required methods and implement that interface in the inherited businessrules class
didn’t see that thx!