Data updater

DataUI.pas

unit DataUI;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, DBCtrls, Grids, DBGrids, DBClient, StdCtrls, DataUnit, DB,
  DBTables;

type
  TForm2 = class(TForm)
    DBNavigator1: TDBNavigator;
    saveDialog: TSaveDialog;
    Button1: TButton;
    Button2: TButton;
    Panel1: TPanel;
    openDialog: TOpenDialog;
    DBGrid1: TDBGrid;

    procedure Button2Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure DBGrid1TitleClick(Column: TColumn);
  private
    { Private declarations }
  public
    { Public declarations }

  end;

Const
  FILE_FILTER1 = 'Text file|*.txt|' + 'Comma-separated values file|*.csv|' +
    'Tab-separated values file|*.tsv|' + 'Tab-separated values file|*.tab|';
  FILE_FILTER2 = 'Extensible Markup Language file|*.xml|' +
    'Delphi TClientDataset data file|*.cds|';

var
  Form2: TForm2;

implementation

{
  Import.
}
procedure TForm2.Button1Click(Sender: TObject);
var
  ext: string;
begin
  openDialog := TOpenDialog.Create(self);
  openDialog.Title := 'Pick a file, to load.';
  openDialog.InitialDir := GetCurrentDir;
  openDialog.Filter := FILE_FILTER2;
  openDialog.DefaultExt := 'cds';
  openDialog.FilterIndex := 2;

  // Display the open file dialog
  if not openDialog.Execute then
    ShowMessage('Action was cancelled')
  else
  begin
    ext := ExtractFileExt(openDialog.FileName);

    if (AnsiCompareText(ext, '.cds') = 0) or
      (AnsiCompareText(ext, '.xml') = 0) then
    begin

      DataModule3.cdsMaster.Close;
      DataModule3.cdsMaster.FileName := openDialog.FileName;
      DataModule3.cdsMaster.Open;
      Button2.Enabled := True;
    end;
  end;

  saveDialog.Free;
end;

{
  Export.
}
procedure TForm2.Button2Click(Sender: TObject);
begin
  saveDialog := TSaveDialog.Create(self);
  saveDialog.Title := 'Pick a file, where to Save your data.';
  saveDialog.InitialDir := GetCurrentDir;
  saveDialog.Filter := FILE_FILTER1 + FILE_FILTER2;
  saveDialog.DefaultExt := 'tab';
  saveDialog.FilterIndex := 4;

  if not saveDialog.Execute then
    ShowMessage('Action was cancelled')
  else
    DataModule3.saveDataSet(saveDialog.FileName);

  saveDialog.Free;
end;

{
  Sorts field ascendingly.
}
procedure TForm2.DBGrid1TitleClick(Column: TColumn);
begin
  try
    DataModule3.cdsMaster.IndexFieldNames := Column.FieldName;
  except
    on E: Exception do
      ShowMessage('Could not sort.');
  end;
end;

{$R *.dfm}

end.

DataUnit.pas

unit DataUnit;

interface

uses
  SysUtils, Classes, DB, DBClient, Dialogs, Provider;

type
  TDataModule3 = class(TDataModule)
    cdsMaster: TClientDataSet;
    cdMaster: TDataSource;
    procedure DataModuleDestroy(Sender: TObject);
    procedure writeTsvRow(var AFile: Textfile);
    procedure writeCsvRow(var AFile: Textfile);
    procedure writeDsvRow(var AFile: Textfile; delimiter: String);
    procedure cdsMasterAfterPost(DataSet: TDataSet);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure saveDataSet(FileName: String);
  end;

var
  DataModule3: TDataModule3;

implementation

{$R *.dfm}

{
  Does `Autosave`.
}
procedure TDataModule3.cdsMasterAfterPost(DataSet: TDataSet);
begin
  if cdsMaster.Active then
  begin
    cdsMaster.SaveToFile(cdsMaster.FileName);
    cdsMaster.Close;
    cdsMaster.LoadFromFile(cdsMaster.FileName);
  end;

end;

{
  TODO: Remove this or add provider and option to use it.
}
procedure TDataModule3.DataModuleDestroy(Sender: TObject);
begin
  // cdsMaster.MergeChangeLog();
end;

{
  Selects appropriate export method.
}
procedure TDataModule3.saveDataSet(FileName: String);
Const
  TAB = Chr(9);
var
  AFile: Textfile;
  I: Integer;
  ext: string;
begin
  ext := ExtractFileExt(FileName);
  if (AnsiCompareText(ext, '.cds') = 0) or
    (AnsiCompareText(ext, '.xml') = 0) then
  begin
    cdsMaster.SaveToFile(FileName);
  end
  else
  begin
    AssignFile(AFile, FileName);
    Rewrite(AFile);

    try
      if (AnsiCompareText(ext, '.tab') = 0) or
        (AnsiCompareText(ext, '.tsv') = 0) then
        writeTsvRow(AFile)
      else if (AnsiCompareText(ext, '.txt') = 0) or
        (AnsiCompareText(ext, '.csv') = 0) then
        writeCsvRow(AFile);
    finally
      CloseFile(AFile);
    end;
  end;

end;
{
  Writes datatable to file, in tab separated format.
}
procedure TDataModule3.writeTsvRow(var AFile: Textfile);
begin
  writeDsvRow(AFile, Chr(9) { This is tab character. } );
end;

{
  Writes datatable to file, in comma separated format.
}
procedure TDataModule3.writeCsvRow(var AFile: Textfile);
begin
  writeDsvRow(AFile, ',');
end;

{
  Writes datatable to file, in delimiter separated format.
  TODO: `cdMaster.DataSet` should be passed as a parameter.
}
procedure TDataModule3.writeDsvRow(var AFile: Textfile; delimiter: String);
var
  I: Integer;
begin
  with cdMaster.DataSet do
  begin
    // field names
    for I := 0 to FieldCount - 2 do
      Write(AFile, Fields[I].FieldName, delimiter);
    Writeln(AFile, Fields[FieldCount - 1].FieldName);

    // content
    First;
    while not cdMaster.DataSet.EOF do
    begin
      for I := 0 to FieldCount - 2 do
        Write(AFile, FieldByName(Fields[I].FieldName).AsString, delimiter);
      Writeln(AFile, FieldByName(Fields[FieldCount - 1].FieldName).AsString);
      Next;
    end;
  end;
end;

end.