وعليكم السلام ورحمة الله
أهلا بعودة AL-MOB4RM3G
كيف نتعامل مع xml في الدلفي؟
يتم التعامل مع XML من خلال مكون TXMLDocument المرفق مع إصدارات دلفي 6 من التبويب Internet
حيث الصيغة النحوية لملفات XML شبيه بالـ HTML ، بإمكانية تخزين عناصر وأبنائها بهذا الشكل:
XMLDocument1.Version := '1.0';
XMLDocument1.Encoding := 'ISO-8859-1';
with XMLDocument1.AddChild('Parent') do
begin
Text := 'father';
AddChild('Child').Text := 'first son';
AddChild('Child2').Text := 'Second son';
end;
XMLDocument1.SaveToFile(FileName);
فيما يخص ملفات ال xml, هل من شئ يميّزها عن غيرها ؟
XML تستخدم محلل (Parser) خاص لقراءة/كتابة البنود
ام انها تستخدم مثلها مثل ملفات ال ini مثلا ؟
أبعد من ذلك... يمكن استخدامها لتخزين/قراءة بيانات جدول (TDataSet)، مثال:
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.
}
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.
كما يمكن استخدامها عوضا عن ملفات INI، مثال:
uses
Forms, SysUtils, Windows, XmlIntf, XMLDoc;
type
TXMLConfig = class
private
FModified: Boolean;
FFileName: string;
FXMLDoc: TXMLDocument;
FBackup: Boolean;
function GetVersion: string;
public
constructor Create(const FileName: string); overload;
constructor Create; overload;
destructor Destroy; override;
procedure Save;
function ReadString(const Section, Key, default: string): string;
procedure WriteString(const Section, Key, Value: string);
function ReadInteger(const Section, Key: string; default: Integer): Integer;
procedure WriteInteger(const Section, Key: string; Value: Integer);
function ReadBoolean(const Section, Key: string; default: Boolean): Boolean;
procedure WriteBoolean(const Section, Key: string; Value: Boolean);
property Backup: Boolean read FBackup write FBackup;
property Version: string read GetVersion;
end;
implementation
{ TXMLConfig }
constructor TXMLConfig.Create(const FileName: string);
begin
inherited Create;
FBackup := True;
FFileName := FileName;
FXMLDoc := TXMLDocument.Create(Application);
FXMLDoc.Options := [doNodeAutoIndent];
if FileExists(FFileName) then
FXMLDoc.LoadFromFile(FFileName)
else
begin
FXMLDoc.Active := True;
FXMLDoc.AddChild('Configuration');
end;
end;
constructor TXMLConfig.Create;
begin
Create(ChangeFileExt(Application.Exename, '_cfg.xml'));
end;
destructor TXMLConfig.Destroy;
begin
Save;
FXMLDoc.Destroy;
inherited;
end;
function TXMLConfig.GetVersion: string;
begin
Result := '1.00';
end;
function TXMLConfig.ReadBoolean(const Section, Key: string; default: Boolean): Boolean;
begin
Result := Boolean(ReadInteger(Section, Key, Integer(default)));
end;
function TXMLConfig.ReadInteger(const Section, Key: string; default: Integer): Integer;
begin
Result := StrToInt(ReadString(Section, Key, IntToStr(default)));
end;
function TXMLConfig.ReadString(const Section, Key, default: string): string;
var
Node: IXMLNode;
begin
Node := FXMLDoc.DocumentElement.ChildNodes.FindNode(Sectio n);
if Assigned(Node) and Node.HasAttribute(Key) then
Result := Node.Attributes[Key]
else
Result := default;
end;
procedure TXMLConfig.Save;
begin
if not FModified then
Exit;
if FBackup then
CopyFile(PChar(FFileName), PChar(FFileName + '.bak'), False);
FXMLDoc.SaveToFile(FFileName);
FModified := False;
end;
procedure TXMLConfig.WriteBoolean(const Section, Key: string; Value: Boolean);
begin
WriteInteger(Section, Key, Integer(Value));
end;
procedure TXMLConfig.WriteInteger(const Section, Key: string; Value: Integer);
begin
WriteString(Section, Key, IntToStr(Value));
end;
procedure TXMLConfig.WriteString(const Section, Key, Value: string);
var
Node: IXMLNode;
begin
if ReadString(Section, Key, '') = Value then
Exit;
Node := FXMLDoc.DocumentElement.ChildNodes.FindNode(Sectio n);
if not Assigned(Node) then
Node := FXMLDoc.DocumentElement.AddChild(Section);
Node.Attributes[Key] := Value;
FModified := True;
end;