Export Classes

type
  TBIExport = class
  public
    Data: TDataItem;      // Data to export
    SchemaOnly: Boolean;  // Export structure only, no data
    
    function AsString: String;  // Export to string
    procedure SaveToFile(const FileName: String);  // Export to file
  end;

type
  TBITextExport = class(TBIExport)
  protected
    procedure DoEmit(const AItems: TStrings); virtual; abstract;
  end;

var
  Export: TBICSVExport;
begin
  Export := TBICSVExport.Create;
  try
    Export.Data := MyData;
    Export.Delimiter := ',';
    Export.Header := True;
    Export.SaveToFile('output.csv');
  finally
    Export.Free;
  end;
end;

var
  Export: TBIJSONExport;
begin
  Export := TBIJSONExport.Create;
  try
    Export.Data := MyData;
    Export.Header := True;
    Export.SaveToFile('output.json');
  finally
    Export.Free;
  end;
end;

var
  Export: TBIXMLExport;
begin
  Export := TBIXMLExport.Create;
  try
    Export.Data := MyData;
    Export.Emit := TBIXMLEmit.Header;
    Export.SaveToFile('output.xml');
  finally
    Export.Free;
  end;
end;

var
  CSV: TBICSVExport;
  Text: String;
begin
  CSV := TBICSVExport.Create;
  try
    CSV.Data := MyData;
    Text := CSV.AsString;  // Get as string instead of file
    Memo1.Text := Text;
  finally
    CSV.Free;
  end;
end;

var
  JSON: TBIJSONExport;
begin
  JSON := TBIJSONExport.Create;
  try
    JSON.Data := MyData;
    JSON.SchemaOnly := True;  // Export structure only
    JSON.SaveToFile('schema.json');
  finally
    JSON.Free;
  end;
end;

procedure TForm1.ExportWithProgress(const Data: TDataItem);
var
  Export: TBICSVExport;
begin
  Export := TBICSVExport.Create;
  try
    Export.Data := Data;
    Export.OnProgress := 
      procedure(Sender: TObject; Percent: Single; var Cancel: Boolean)
      begin
        ProgressBar1.Position := Round(Percent);
        Application.ProcessMessages;
        Cancel := FCancelExport;  // User can cancel
      end;
    
    Export.SaveToFile('large_file.csv');
  finally
    Export.Free;
  end;
end;

TPersistence.Save(MyData, 'data.bi');

TDataItemPersistence.Save(MyData, 'complete.bidata');

// Save structure
TPersistence.Save(MyData, 'schema.bi');

// Save data
TDataPersistence.Save(MyData, 'data.databi');

// From TBITextExport
class procedure SaveToFile(const Text, FileName: String);

// Usage
TBICSVExport.SaveToFile(MyCSVText, 'output.csv');

var
  Filters: TFileFilters;
begin
  Filters := TBICSVExport.FileFilter;
  // Returns: 'CSV (Comma separated values)|*.csv|TSV (Tab separated values)|*.tsv'
  
  OpenDialog1.Filter := Filters.AsString;
end;

type
  TMyExporter = class(TBITextExport)
  protected
    procedure DoEmit(const AItems: TStrings); override;
  public
    class function FileFilter: TFileFilters; override;
    class function Supports(const Extension: String): Boolean; override;
  end;

implementation

procedure TMyExporter.DoEmit(const AItems: TStrings);
var
  i: Integer;
begin
  // Custom export logic
  for i := 0 to Data.Count - 1 do
  begin
    AItems.Add(Data.Items[0].TextData[i]);
  end;
end;

class function TMyExporter.FileFilter: TFileFilters;
begin
  Result := nil;
  Result.Add('My Format', '*.myf');
end;

class function TMyExporter.Supports(const Extension: String): Boolean;
begin
  Result := SameText(Extension, '.myf');
end;

initialization
  TBIExporters.RegisterClass(TMyExporter);
  
finalization
  TBIExporters.UnRegisterClass(TMyExporter);
end.