TStringStream to BlobStream

[mr_fahrrad]

Hi

I have a problem when I try use the copyFrom to copy a BlobStream from a StringStream

Delphi-Quellcode:

procedure TfrmHelpEdt.sButton2Click(Sender: TObject);
var
blob:TStream;
StringStream : TStream;
begin

  with ADOTbl_HTDATA do //is a AdoTable
    begin
      Active:=true;
      Insert;
       blob:=CreateBlobStream(FieldByName('HD_source'), bmWrite);
       StringStream:=TStringStream.Create(getHtml); //getHTML function Return a string
       blob.Position:=0;
       blob.Seek(0, soFromBeginning);
       blob.CopyFrom(StringStream, StringStream.size);
      Post;
      Active:=false;
    end;

The field HD_Source not allow null and the error say "cannot insert null value in hd_source"...
so, I belive that error is in the line blob.CopyFrom(StringStream, StringStream.size);

Can anyone help me?

[Der_Unwissende]

Hi,
these lines look a little redundant

Zitat von mr_fahrrad:

Delphi-Quellcode:

  blob.Position:=0;
  blob.Seek(0, soFromBeginning);

The both of them should do the same, but

Zitat von mr_fahrrad:

Delphi-Quellcode:

  blob.Position:=0;
  StringStream.Position := 0;

should do better (untested, I might be wrong)

Regards, Der Unwissende

[ADD]
If HD_source is non-nullable, you probably should ensure that getHTML returns a valid string (<> '')
[/ADD]

[Muetze1]

The 2nd parameter of CopyFrom() (the size) can be zero, if you want to copy the whole passed stream. In this case, the source stream will also be seeked to position 0 before copy. Otherwise (if you pass any size value > 0), you have to ensure that the read position is as expected on zero position before calling CopyFrom()