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#79: How can I export a dataset into XML file?

Sometimes in our development we must export a data from dataset into different formats like MS Excel, Word, HTML, Text etc. Now in the Internet we have a new popular format - XML-file. So for large part of applications we wants to include the possibility of export into XML, of course. I want to demonstrate the sample of one procedure for exporting of dataset's data into XML:

procedure DatasetToXML(Dataset: TDataset; FileName: string);

The first Dataset parameter is source dataset with data (your Table or Query component, or some other third-party dataset). The second FileName parameter is a name of target XML-file.

{ SMExport suite's free demo
  Data export from dataset into XML-file

  Copyright(C) 2000, written by Scalabium, Shkolnik Mike
  E-Mail:  smexport@scalabium.com
           mshkolnik@yahoo.com
  WEB: http://www.scalabium.com
       http://www.geocities.com/mshkolnik
}
unit DS2XML;

interface

uses
  Classes, DB;

procedure DatasetToXML(Dataset: TDataset; FileName: string);

implementation

uses
  SysUtils;

var
  SourceBuffer: PChar;

procedure WriteString(Stream: TFileStream; s: string);
begin
  StrPCopy(SourceBuffer, s);
  Stream.Write(SourceBuffer[0], StrLen(SourceBuffer));
end;

procedure WriteFileBegin(Stream: TFileStream; Dataset: TDataset);

  function XMLFieldType(fld: TField): string;
  begin
    case fld.DataType of
      ftString: Result := '"string" WIDTH="' + IntToStr(fld.Size) + '"';
      ftSmallint: Result := '"i4"'; //??
      ftInteger: Result := '"i4"';
      ftWord: Result := '"i4"'; //??
      ftBoolean: Result := '"boolean"';
      ftAutoInc: Result := '"i4" SUBTYPE="Autoinc"';
      ftFloat: Result := '"r8"';
      ftCurrency: Result := '"r8" SUBTYPE="Money"';
      ftBCD: Result := '"r8"'; //??
      ftDate: Result := '"date"';
      ftTime: Result := '"time"'; //??
      ftDateTime: Result := '"datetime"';
    else
    end;
    if fld.Required then
      Result := Result + ' required="true"';
    if fld.Readonly then
      Result := Result + ' readonly="true"';
  end;

var
  i: Integer;
begin
  WriteString(Stream, '<?xml version="1.0" standalone="yes"?><!-- Generated by SMExport -->  ' +
                      '<DATAPACKET Version="2.0">');
  WriteString(Stream, '<METADATA><FIELDS>');

  {write th metadata}
  with Dataset do
    for i := 0 to FieldCount-1 do
    begin
      WriteString(Stream, '<FIELD attrname="' +
                          Fields[i].FieldName +
                          '" fieldtype=' +
                          XMLFieldType(Fields[i]) +
                          '/>');
    end;
  WriteString(Stream, '</FIELDS>');
  WriteString(Stream, '<PARAMS DEFAULT_ORDER="1" PRIMARY_KEY="1" LCID="1033"/>');
  WriteString(Stream, '</METADATA><ROWDATA>');
end;

procedure WriteFileEnd(Stream: TFileStream);
begin
  WriteString(Stream, '</ROWDATA></DATAPACKET>');
end;

procedure WriteRowStart(Stream: TFileStream; IsAddedTitle: Boolean);
begin
  if not IsAddedTitle then
    WriteString(Stream, '<ROW');
end;

procedure WriteRowEnd(Stream: TFileStream; IsAddedTitle: Boolean);
begin
  if not IsAddedTitle then
    WriteString(Stream, '/>');
end;

procedure WriteData(Stream: TFileStream; fld: TField; AString: ShortString);
begin
  if Assigned(fld) and (AString <> '') then
    WriteString(Stream, ' ' + fld.FieldName + '="' + AString + '"');
end;

function GetFieldStr(Field: TField): string;

  function GetDig(i, j: Word): string;
  begin
    Result := IntToStr(i);
    while (Length(Result) < j) do
      Result := '0' + Result;
  end;

var Hour, Min, Sec, MSec: Word;
begin
  case Field.DataType of
    ftBoolean: Result := UpperCase(Field.AsString);
    ftDate: Result := FormatDateTime('yyyymmdd', Field.AsDateTime);
    ftTime: Result := FormatDateTime('hhnnss', Field.AsDateTime);
    ftDateTime: begin
                  Result := FormatDateTime('yyyymmdd', Field.AsDateTime);
                  DecodeTime(Field.AsDateTime, Hour, Min, Sec, MSec);
                  if (Hour <> 0) or (Min <> 0) or (Sec <> 0) or (MSec <> 0) then
                    Result := Result + 'T' + GetDig(Hour, 2) + ':' + GetDig(Min, 2) + ':' + GetDig(Sec, 2) + GetDig(MSec, 3);
                end;
  else
    Result := Field.AsString;
  end;
end;

procedure DatasetToXML(Dataset: TDataset; FileName: string);
var
  Stream: TFileStream;
  bkmark: TBookmark;
  i: Integer;
begin
  Stream := TFileStream.Create(FileName, fmCreate);
  SourceBuffer := StrAlloc(1024);
  WriteFileBegin(Stream, Dataset);

  with DataSet do
  begin
    DisableControls;
    bkmark := GetBookmark;
    First;

    {write a title row}
    WriteRowStart(Stream, True);
    for i := 0 to FieldCount-1 do
      WriteData(Stream, nil, Fields[i].DisplayLabel);
    {write the end of row}
    WriteRowEnd(Stream, True);

    while (not EOF) do
    begin
      WriteRowStart(Stream, False);
      for i := 0 to FieldCount-1 do
        WriteData(Stream, Fields[i], GetFieldStr(Fields[i]));
      {write the end of row}
      WriteRowEnd(Stream, False);

      Next;
    end;

    GotoBookmark(bkmark);
    EnableControls;
  end;

  WriteFileEnd(Stream);
  Stream.Free;
  StrDispose(SourceBuffer);
end;


end.

PS: I created this simple procedure from own TSMExportToXML component which have a lot of other useful extensions in export process. This component is part of shareware SMExport suite for Delphi/C++Builder so I cutted a part of code and created a simple procedure for exporting into XML.

Published: May 24, 2000

See also

	Paradox to Text converter
	DBLoad
	Clarion Viewer
	SMImport suite
	dBase Viewer
	Excel Reader (dll)
	Clarion to Text converter
	DBExport tools
	Viewer for MS Outlook Messages
	ExcelFile Viewer

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