请教 用ClientDataSet存取Bolb字段!!

Question

var
  Stream:TMemoryStream;
  Stream1:TStream;
begin
  with form1.ClientDataSet1 do
  begin
    Edit;
    Stream:=TMemoryStream.Create;
    Stream.Position:=0;
    form1.Memo1.Lines.SaveToStream(Stream);
    Stream1:=CreateBlobStream(FieldByName('BlobField'),bmReadWrite);
    try
      Stream1.CopyFrom(Stream,Stream.Size);//这里出错"Stream Read Error"
      Post;
    finally
      Stream1.Free;
    end;
    Stream.Free;
  end;
为什么呢?

Answer 1

如此改写：
      ...
      Stream1:=CreateBlobStream(FieldByName('BlobField') as TBlobField,bmWrite);
     try
       Stream1.Assign(Stream);
      ....
我是这么写的，一切正常

Answer 2

Stream1.CopyFrom(Stream,Stream.Size);//这里出错"Stream Read Error"
依旧!!!!!!!!
高手,在哪里;高手,在闪烁!

Answer 3

var
  Stream:TMemoryStream;
  Stream1:TStream;
begin
  with form1.ClientDataSet1 do
  begin
    Edit;
    Stream:=TMemoryStream.Create;
   // Stream.Position:=0;(原先)
    form1.Memo1.Lines.SaveToStream(Stream);
    Stream.Position:=0;驱 //(现在)
    Stream1:=CreateBlobStream(FieldByName('BlobField'),bmReadWrite);
    try
      Stream1.CopyFrom(Stream,Stream.Size);//不出错"Stream Read Error"
      Post;
    finally
      Stream1.Free;
    end;
    Stream.Free;
  end;
但是没有保存到记录中!????

Answer 4

老兄：
   问题出在以下位置：
   1。Stream.Position:=0;
     form1.Memo1.Lines.SaveToStream(Stream);
  改为：
     form1.Memo1.Lines.SaveToStream(Stream);
      Stream.Position:=0;
  2，Post;
     把Post去掉即可，否则会重复保存，所以报错     

Answer 5

var
  Stream:TMemoryStream;
  Stream1:TStream;
begin
  with form1.ClientDataSet1 do
  begin
    Edit;
    Stream:=TMemoryStream.Create;
    form1.Memo1.Lines.SaveToStream(Stream);
    Stream.Position:=0;
    Stream1:=CreateBlobStream(FieldByName('BlobField'),bmReadWrite);
    try
      Stream1.CopyFrom(Stream,Stream.Size);
      Post;
    finally
      Stream1.Free;
    end;
    Stream.Free;
  end;
 已经在 AfterPost 里写了 applyupdate
但是仍没有保存到记录中!????

Answer 6

var
  Stream:TMemoryStream;
begin
  with form1.ClientDataSet1 do
  begin
    Edit;
    Stream:=TMemoryStream.Create;
    form1.Memo1.Lines.SaveToStream(Stream);
    Stream.Position:=0;
    try
      TBlobField(FieldByName('BlobField')).LoadFromStream(Stream);
      Post;
    finally
      Stream.Free;
    end;
  end;
 已经在 AfterPost 里写了 applyupdate
但是
ORA-01465 : 无效的十六进制数字
快疯了!