Datensätze aus Tabelle holen und in Datei speichern

**Sir Rufo**

Also hierfür bietet sich das

Strategy Design Pattern an.

Hier eine beispielhafte Umsetzung

Delphi-Quellcode:

			unit Document;

interface

type

  TDocument = class;

  IDocumentExportFileStrategy = interface

    ['{787B60E5-A3CA-485C-A46E-248A43D7175C}']

    procedure ExportDoc( AContext : TDocument; const AFileName : string );

  end;

  TDocument = class

  private

    FExportFileStrategy : IDocumentExportFileStrategy;

  protected

    function GetValue( const Name : string ) : Variant; virtual; abstract;

  public

    procedure First; virtual; abstract;

    procedure Next; virtual; abstract;

    function Eof : Boolean; virtual; abstract;

    property Value[const Name : string] : Variant read GetValue;

    property ExportFileStrategy : IDocumentExportFileStrategy read FExportFileStrategy write FExportFileStrategy;

    procedure ExportTo( const AFileName : string );

  end;

implementation

{ TDocument }

procedure TDocument.ExportTo( const AFileName : string );

begin

  FExportFileStrategy.ExportDoc( Self, AFileName );

end;

end.

Die Export-Strategie für Xliff (Plain-Text)

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Delphi-Quellcode:

			unit XliffPlainExporter;

interface

uses

  Document,

  SysUtils, Variants,

  Classes;

type

  TXliffPlainExporter = class( TInterfacedObject, IDocumentExportFileStrategy )

  private

    procedure WriteLine( AStream : TStream; ALine : string );

  protected

    procedure WriteHead( AContext : TDocument; AStream : TStream );

    procedure WriteDetails( AContext : TDocument; AStream : TStream );

    procedure WriteFoot( AContext : TDocument; AStream : TStream );

  public

    procedure ExportDoc( AContext : TDocument; const AFileName : string );

  end;

implementation

{ TXmlExporter }

procedure TXliffPlainExporter.ExportDoc( AContext : TDocument; const AFileName : string );

var

  LStream :   TStream;

  LFileName : string;

begin

  AContext.First;

  if not AContext.Eof

  then

    begin

      LFileName := AFileName;

      if ExtractFileExt( LFileName ) = ''

      then

        LFileName := ChangeFileExt( LFileName, '.xml' );

      LStream := TFileStream.Create( LFileName, fmCreate );

      try

        WriteHead( AContext, LStream );

        WriteDetails( AContext, LStream );

        WriteFoot( AContext, LStream );

      finally

        LStream.Free;

      end;

    end;

end;

procedure TXliffPlainExporter.WriteHead( AContext : TDocument; AStream : TStream );

begin

  WriteLine( AStream, '<?xml version=''1.0'' encoding=''utf-8''?>' );

  WriteLine( AStream, '<xliff version="1.1">' );

  WriteLine( AStream, '  <file original="source\simple.htm" source-language="EN" target-language="DE" datatype="html">' );

  WriteLine( AStream, '    <header>' );

  WriteLine( AStream, '      <skl>' );

  WriteLine( AStream, '        <external-file uid="017dbcf0-c82c-11e2-ba2b-005056c00008" href="skl\simple.htm.skl"/>' );

  WriteLine( AStream, '      </skl>' );

  WriteLine( AStream, '    </header>' );

  WriteLine( AStream, '    <body>' );

end;

procedure TXliffPlainExporter.WriteDetails( AContext : TDocument; AStream : TStream );

begin

  while not AContext.Eof do

    begin

      WriteLine( AStream, Format( '      <trans-unit id="%s">', [VarToStr( AContext.Value['id'] )] ) );

      WriteLine( AStream, Format( '        <source xml:lang="EN">%s</source>', [VarToStr( AContext.Value['src'] )] ) );

      WriteLine( AStream, Format( '        <target xml:lang="DE">%s</target>', [VarToStr( AContext.Value['dst'] )] ) );

      WriteLine( AStream, '      <note/></trans-unit>' );

      AContext.Next;

    end;

end;

procedure TXliffPlainExporter.WriteFoot( AContext : TDocument; AStream : TStream );

begin

  WriteLine( AStream, '    </body>' );

  WriteLine( AStream, '  </file>' );

  WriteLine( AStream, '</xliff>' );

end;

procedure TXliffPlainExporter.WriteLine( AStream : TStream; ALine : string );

var

  LLine : TStream;

begin

  LLine := TStringStream.Create( ALine + sLineBreak, TEncoding.UTF8 );

  try

    LLine.Position := 0;

    AStream.CopyFrom( LLine, LLine.Size );

  finally

    LLine.Free;

  end;

end;

end.

Ein konkretes Test-Dokument

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Delphi-Quellcode:

			unit TestDocument;

interface

uses

  Document;

type

  TTestDocument = class( TDocument )

  private

    FIndex : Integer;

  protected

    function GetValue( const Name : string ) : Variant; override;

  public

    function Eof : Boolean; override;

    procedure First; override;

    procedure Next; override;

  end;

implementation

uses

  SysUtils,

  StrUtils;

{ TTestDocument }

function TTestDocument.Eof : Boolean;

begin

  Result := FIndex >= 100;

end;

procedure TTestDocument.First;

begin

  inherited;

  FIndex := 0;

end;

function TTestDocument.GetValue( const Name : string ) : Variant;

begin

  case IndexText( Name, ['id', 'src', 'dst'] ) of

    0 :

      Result := Format( 'id%8.8d', [FIndex + 1] );

    1 :

      Result := Format( 'src%8.8d', [FIndex + 1] );

    2 :

      Result := Format( 'dst%8.8d', [FIndex + 1] );

  end;

end;

procedure TTestDocument.Next;

begin

  inherited;

  Inc( FIndex );

end;

end.

und das Hauptprogramm zum Testen

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Delphi-Quellcode:

			program DataExportStrategy;

{$APPTYPE CONSOLE}

{$R *.res}

uses

  System.SysUtils,

  Document in 'Document.pas',

  TestDocument in 'TestDocument.pas',

  XliffPlainExporter in 'XliffPlainExporter.pas';

procedure Test;

var

  LDoc : TDocument;

begin

  LDoc := TTestDocument.Create;

  try

    LDoc.ExportFileStrategy := TXliffPlainExporter.Create;

    LDoc.ExportTo( 'test' );

  finally

    LDoc.Free;

  end;

  WriteLn( 'Export finished' );

end;

begin

  try

    Test;

  except

    on E : Exception do

      WriteLn( E.ClassName, ': ', E.Message );

  end;

  ReadLn;

end.

Wenn du ein TDataSetDocument benötigst, dann bau es dir so

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Delphi-Quellcode:

			unit DataSetDocument;

interface

uses

  Document,

  Data.DB;

type

  TDataSetDocument = class( TDocument )

  private

    FDataSet : TDataSet;

  protected

    function GetValue( const Name : string ) : Variant; override;

  public

    constructor Create( ADataSet : TDataSet );

    function Eof : Boolean; override;

    procedure Next; override;

    procedure First; override;

  end;

implementation

{ TDataSetDocument }

constructor TDataSetDocument.Create( ADataSet : TDataSet );

begin

  inherited Create;

  FDataSet := ADataSet;

end;

function TDataSetDocument.Eof : Boolean;

begin

  Result := FDataSet.Eof;

end;

procedure TDataSetDocument.First;

begin

  inherited;

  FDataSet.First;

end;

function TDataSetDocument.GetValue( const Name : string ) : Variant;

begin

  Result := FDataSet.FieldByName( Name ).Value;

end;

procedure TDataSetDocument.Next;

begin

  inherited;

  FDataSet.Next;

end;

end.

und fertig ...

Benötigst du weitere (oder anders funktionierende) Export-Formate (z.B. CSV oder XML mit XMLDoc), dann einfach eine neue Strategie-Klasse implemetieren, dem Document zuweisen und Exportieren lassen.

Datensätze aus Tabelle holen und in Datei speichern

AW: Datensätze aus Tabelle holen und in Datei speichern

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