Example: TcxCustomDataSource.AppendRecord, TcxCustomDataSource.InsertRecord

• Jul 29, 2021

Assume that you implement a custom data source from an external TStringList object (FStringList). The AppendRecord method should add a new string at the end of the list. The InsertRecord method should insert a new item in this list at the position specified by the ARecordHandle parameter by moving all following items to the end of the list. Both AppendRecord and InsertRecord should return the index of the new item as a record handle and call the DataChanged method. For information on record handles, see the TcxCustomDataSource topic.

Delphi

type
  TUserDataSource = class(TcxCustomDataSource)
  private
    FStringList: TStringList;
  protected
    //...
    function AppendRecord: Pointer; override;
    function InsertRecord(ARecordHandle: Pointer): Pointer; override;
  end;
implementation
//...
function TUserDataSource.AppendRecord: Pointer;
begin
  Result := Pointer(FStringList.Add(''));
  DataChanged;
end;
function TUserDataSource.InsertRecord(ARecordHandle: Pointer): Pointer;
begin
  FStringList.Insert(Integer(ARecordHandle), '');
  Result := ARecordHandle;
  DataChanged;
end;

C++

class TUserDataSource: public TcxCustomDataSource {
  private:
    TStringList * FStringList;
  protected:
    //...
    virtual void * __fastcall AppendRecord(void);
    virtual void * __fastcall InsertRecord(void * ARecordHandle);
};
//...
void * __fastcall TUserDataSource::AppendRecord(void) {
  int res = FStringList->Add("");
  DataChanged();
  return (void*)res;
}
void * __fastcall TUserDataSource::InsertRecord(void * ARecordHandle) {
  FStringList->Insert((int)ARecordHandle, "");
  DataChanged();
  return ARecordHandle;
}