CODEWITHSUNDEEP
delphitclientdataset
edbored
edbored

Reputation: 274

How to apply TClientDataSet StatusFilter on fkData only

I having a bit of an issue tracking the changes to just fkData fields in a ClientDataSet.

There are fkInternalCalc fields that I populate and change quite a bit while using the program (I'll use an fkInternalCalc field to drive calculations to other fkInternalCalc fields).

I can call CDS.ChangeCount and get a result of 0 (because none of the fkData fields have actually changed).

But when I call CDS.StatusFilter:=[usModified] I see many records - because while ChangeCount ignores fkInternalCalc, StatusFilter doesn't - it shows changes to everything.

Am I missing some mechanism whereby I can filter by (usmodified and fkData)?

(I can't use simple fkCalculated for a variety of performance reasons)

Using Delphi Tokyo Enterprise.

TIA Cheers, EdB

Upvotes: 1

Views: 202

Answers (1)

MartynA
MartynA

Reputation: 30715

I think the code below will do what you want, if I understand you correctly. It's just a test-bed, requires 2 CDSs each with a datasource and grid.

As you can see, the ClientDataSet1Value field gets updated every time a change is posted to the first CDS, but the second CDS only shows rows where an fkData field has been changed;

procedure TForm1.FormCreate(Sender: TObject);
var
  i : Integer;
begin
  {
  ClientDataSet1ID: TIntegerField;  // fkData
  ClientDataSet1Name: TStringField;  // fkData
  ClientDataSet1SaveCount: TIntegerField;  // fkInternalCalc
  }
  ClientDataSet1.CreateDataSet;
  for i := 1 to 3 do
    ClientDataSet1.InsertRecord([i, 'name of ' + IntToStr(i)]);
end;

procedure TForm1.ClientDataSet1BeforePost(DataSet: TDataSet);
begin
  if ClientDataSet1SaveCount.IsNull then
    ClientDataSet1SaveCount.AsInteger := 1
  else
    ClientDataSet1SaveCount.AsInteger := 1 + ClientDataSet1SaveCount.AsInteger;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  ClientDataSet2.Data := ClientDataSet1.Data;
  ClientDataSet2.StatusFilter := [usModified];
end;

After Button2Click, the grid for the second CDS will be displaying only the rows whose fKData field(s) have been modified, or a single blank row if none of the rows have modified fkData field data.

Upvotes: 1

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