Probleme mit Objektkopie und eigenem MessageDialog

[haentschman]

Hallöle...

Ich stehe wieder mal vor einem Problem das ich nicht verstehe...

Gegeben:
* Klasse:

Delphi-Quellcode:

TDocumentProperties = class(TBaseObject)
  strict private
  {$REGION 'Fields'}
    FStoreLocation: string;
    FStoreStreet: string;
    FReceiptReciverName: string;
    FDocumentTypeString: string;
    FDocumentChoiceString: string;
    FDocumentLocation: TSEAMDocumentLocation;
    FStoreName: string;
    FCreateDate: TDateTime;
    FCreateName: string;
    FCreateYear: Integer;
    FModifiedName: string;
    FModifiedDate: TDateTime;
    FDocumentChoice: TSEAMDocumentChoice;
    FServiceDate: TDateTime;
    FNote: string;
    FStoreCountry: string;
    FReceiptDate: TDateTime;
    FStorePostCode: string;
    FReceiptReciverNumber: string;
    FServicePartnerNumber: string;
    FLocationNumber: string;
    FReceiptNumber: string;
    FStoreName_1: string;
    FDocumentCaption: string;
    FStoreNumber: string;
    FFileName: string;
    FFilePath: string;
    FExtension: string;
    FSendType: string;
    FFileNameContent: TStringList;
    procedure SetExtension(const Value: string);
    procedure SetFileName(const Value: string);
  {$ENDREGION}
  public
    constructor Create;
    destructor Destroy; override;
    property StoreNumber: string read FStoreNumber write FStoreNumber;
    property StoreName: string read FStoreName write FStoreName;
    property StoreName_1: string read FStoreName_1 write FStoreName_1;
    property StoreStreet: string read FStoreStreet write FStoreStreet;
    property StoreCountry: string read FStoreCountry write FStoreCountry;
    property StorePostCode: string read FStorePostCode write FStorePostCode;
    property StoreLocation: string read FStoreLocation write FStoreLocation;
    property Note: string read FNote write FNote;
    property CreateDate: TDateTime read FCreateDate write FCreateDate;
    property CreateName: string read FCreateName write FCreateName;
    property CreateYear: Integer read FCreateYear write FCreateYear;
    property ModifiedDate: TDateTime read FModifiedDate write FModifiedDate;
    property ModifiedName: string read FModifiedName write FModifiedName;
    property ReceiptDate: TDateTime read FReceiptDate write FReceiptDate;
    property ServiceDate: TDateTime read FServiceDate write FServiceDate;
    property DocumentChoice: TSEAMDocumentChoice read FDocumentChoice write FDocumentChoice;
    property DocumentLocation: TSEAMDocumentLocation read FDocumentLocation write FDocumentLocation;
    property DocumentChoiceString: string read FDocumentChoiceString write FDocumentChoiceString;
    property DocumentTypeString: string read FDocumentTypeString write FDocumentTypeString;
    property DocumentCaption: string read FDocumentCaption write FDocumentCaption;
    property SendType: string read FSendType write FSendType;
    property ReceiptNumber: string read FReceiptNumber write FReceiptNumber;
    property ReceiptReceiverNumber: string read FReceiptReciverNumber write FReceiptReciverNumber;
    property ReceiverReceiverName: string read FReceiptReciverName write FReceiptReciverName;
    property ServicePartnerNumber: string read FServicePartnerNumber write FServicePartnerNumber;
    property LocationNumber: string read FLocationNumber write FLocationNumber;
    property Extension: string read FExtension write SetExtension;
    property FileName: string read FFileName write SetFileName;
    property FilePath: string read FFilePath write FFilePath;
    procedure Assign(Source: TObject);
    function EncodeFileName: string;
    procedure DecodeFileName(FileName: string);
  end;

* GUI

Delphi-Quellcode:

procedure TfoDocuments.DoScrollDocuments(FocusedRecord: TcxCustomGridRecord);
var
  MessageList: TStringList;
  FileName: string;

  Test1, Test2: Pointer;
begin
  if FLogic.DocumentDatasource.Changed then
  begin
    MessageList := TStringList.Create;
    try
      FileName := FLogic.ModifiedDocument.FileName;
      MessageList.Add(Format(conTextConfirmationChangedDocument, [QuotedStr(FileName)]));
      MessageList.Add('');
      MessageList.Add(conTextConfirmationChangedDocument_1);
      if TMessageDialog.MessageDlg(MessageList, conTextSaveHeader, vmtQuestion, [buYes, buNo], clBlack, Self) = mrYes then
      begin
        FLogic.SaveDocument;
      end;
    finally
      MessageList.Free;
    end;
  end;

  FLogic.AfterScrollDocuments(FocusedRecord.RecordIndex); // Wechsel des Objekte in der Logic

  Test1 := Pointer(FLogic.OriginalDocument); // Kontrolle
  Test2 := Pointer(FLogic.ModifiedDocument); // Kontrolle

  if FLogic.ModifiedDocument.FileName.EndsWith('.pdf', True) then
  begin
    if FileExists(FLogic.ModifiedDocument.FileName) then
    begin
      WPViewPDF1.LoadFromFile(FLogic.ModifiedDocument.FileName);
    end
    else
    begin
      WPViewPDF1.Clear;
      TMessageDialog.MessageDlg(Format(conErrorFileNotPresent, [QuotedStr(FLogic.ModifiedDocument.FileName)]), conTextCheckHeader, vmtError, [buOk], clBlack, Self); // --> Zugriffsverletzung aus dem TReader im OnCreate der Dialog Form (siehe Unit)
    end;
  end;

  ShowDocument(FLogic.ModifiedDocument);
end;

* Logic

Delphi-Quellcode:

constructor TFormDocumentsLogic.Create(Preferences: TSEAMPreferences);
begin
  inherited Create(Preferences);
  FDocumentDatasource := TSEAMDocumentsDatasource.Create;
  FDocumentDatasource.OnChange := DoOnChange;
  FOriginalDocument := nil; // aus Liste
  FModifiedDocument := nil; // über Objektkopie
  FLastStoreName := '';
end;
...
procedure TFormDocumentsLogic.AfterScrollDocuments(FocusedRecordIndex: Integer);
begin
  FOriginalDocument := FDocumentDatasource.GetObject(FocusedRecordIndex); // Pointer aus Liste bleibt unangetastet
  if Assigned(FModifiedDocument) then // mit jedem Scroll die "Kopie" austauschen
  begin
    FModifiedDocument.Free;
  end;
  FModifiedDocument := TSEAMDocumentProperties(TSEAMToolsJson.ObjectCopy(FOriginalDocument)); // Kopie des Originals aus der Liste 
  //wenn ich diese Zeile auskommentiere wird der Dialog angezeigt. 
end;

* Objektkopie (funktioniert eigentlich immer)

Delphi-Quellcode:

class function TToolsJson.ObjectCopy(aValue: TObject): TObject;
var
  MarshalObj: TJSONMarshal;
  UnMarshalObj: TJSONUnMarshal;
  JSONValue: TJSONValue;
begin
  Result := nil;
  MarshalObj := TJSONMarshal.Create;
  try
    UnMarshalObj := TJSONUnMarshal.Create;
    try
      JSONValue := MarshalObj.Marshal(aValue);
      try
        if Assigned(JSONValue) then
          Result := UnMarshalObj.Unmarshal(JSONValue);
      finally
        JSONValue.Free;
      end;
    finally
      UnMarshalObj.Free;
    end;
  finally
    MarshalObj.Free;
  end;
end;

Problem:
1. Wenn ich ausschließlich das Originalobjekt oder ein leeres Objekt benutze (ohne FModifiedDocument Kopie), dann wird der Dialog angezeigt.

Delphi-Quellcode:

FModifiedDocument := TDocumentProperties.Create;  //(TToolsJson.ObjectCopy(FOriginalDocument));
.

2. Wenn ich das Originalobjekt kopiere, auch bei der Benutzung von FOriginalDocument, kommt eine Zugriffsverletzung im OnCreate der Dialog Form.


Frage:
Was hat der Reader der Form damit zu tun? Der Code des MessageDialogs ist in Ordnung...


Danke...