Best practice for dispaying master detail

WEB TMS WEB Core
1

Hi,


On a form I have a  TWebDBGrid1 (the master grid) connected to a TXDataWebDataSet via a TWebDataSource.  

I also have a second grid to show the detail data for a selected row in the master grid with its own TWebDataSource and TXDataWebDataSet

My problem is to get the active record in the master TWebDBGrid1 after scrolling to a new record.
It seems the OnDataChange event of a TWebDataSource does not fire upon scrolling and the AfterScoll event of a TXDataWebDataSet fires for all the records even if you scroll only one record.

The only way I'm able to display detail records of a master record is to use a button with code like this:
procedure TForm1.WebButton2Click(Sender: TObject);
var
  Code: string;
begin
  Code := #39 + xdsDepartments.FieldByName('DeptCode').AsString + #39;

  xdsSTKMaster.QueryString := '$filter=DeptCode eq ' + Code;
  xdsSTKMaster.Load;
end;

Regards,

Nols Smit

2

Hello Nols,

We don't see such behavior here. Maybe you can send us a test project that reproduces the problem (preferable connecting to your server in the cloud). Here AfterScroll works normally, and there you could perform the mentioned request.
3

I tested it again on the music server and the OnDataChange event of the TWebDataSouce does not fire with record changes.  My form and source:



unit uMainUnit;

interface

uses
  System.SysUtils, System.Classes, JS, Web, WEBLib.Graphics, WEBLib.Controls,
  WEBLib.Forms, WEBLib.Dialogs, Data.DB, WEBLib.DB, WEBLib.DBCtrls, Vcl.Controls, Vcl.Grids,
  XData.Web.JsonDataset, XData.Web.Dataset, XData.Web.Connection, Vcl.StdCtrls, WEBLib.StdCtrls;

type
  TMainForm = class(TWebForm)
    XDataWebConnection1: TXDataWebConnection;
    XDataWebDataSet1: TXDataWebDataSet;
    WebDBGrid1: TWebDBGrid;
    WebDBNavigator1: TWebDBNavigator;
    WebDataSource1: TWebDataSource;
    XDataWebDataSet1Artist: TXDataWebEntityField;
    XDataWebDataSet1Id: TIntegerField;
    XDataWebDataSet1Name: TStringField;
    WebButton1: TWebButton;
    WebLabel1: TWebLabel;
    procedure XDataWebConnection1Connect(Sender: TObject);
    procedure WebButton1Click(Sender: TObject);
    procedure WebDataSource1DataChange(Sender: TObject; Field: TField);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  MainForm: TMainForm;

implementation

{$R *.dfm}

procedure TMainForm.WebButton1Click(Sender: TObject);
begin
  XDataWebConnection1.Connected := true;
end;

procedure TMainForm.WebDataSource1DataChange(Sender: TObject; Field: TField);
begin
  WebLabel1.Caption := XDataWebDataSet1.FieldByName('Artist').AsString + ' ' + XDataWebDataSet1.FieldByName('Name').AsString;
end;

procedure TMainForm.XDataWebConnection1Connect(Sender: TObject);
begin
  XDataWebDataSet1.Load;
end;

end.

4

Hi Nols, we will check what is going on with OnDataChange. Maybe there is an issue.

But you can use AfterScroll, did you have a problem with it?
5

We found the issue with OnDataChange, next version will have a fix for it. In the meanwhile you can use AfterScroll event.

6

AfterScroll works OK for a TWebClientDataSet but not for a TXDataWebDatset - it fires for all the records

7

Can you please explain what do you mean by "fires for all the records"? Can you provide steps to reproduce the issue?

8

When you visually move to the next/previous record, AfterScroll  iterates thru all records in the TXDataWebDatset

9

Is this with TMS WEB Core v1.4?
If not, can you please try with TMS WEB Core v1.4?

10

Tested it on v1.4 and the problem remains