Firebird BYTES data type not compatible with TBlobStream

[MN7]

BYTES field raises error
'Exception TZAbstractCLob in module Test.exe at 00000000007623A6.'
in this code:

Code: Select all

  BlobStream := FZQuery.CreateBlobStream(f, bmRead);
  try
    BlobSize := BlobStream.Size;
    BlobStream.Read(BlobMem^, BlobSize);
  finally
    BlobStream.Free;
  end;

BYTES data field have for example security3.fdb in FB 3.0 installation.

[aehimself]

Hello,

You can try reading it to a stream and then converting it to TBytes:

Code: Select all

Var
 ms: TMemoryStream;
 tb: TBytes;
Begin
 ms := TMemoryStream.Create;
 Try
  (ZQuery.FieldByName('TheField') As TBlobField).SaveToStream(ms);
  ms.Position := 0;
  SetLength(tb, ms.Size);
  ms.Read(tb, ms.Size);
  // Do something
 Finally
  FreeAndNil(ms);
 End;
End;

This usually worked for me.

[MN7]

For me works "f.AsBytes".
But "BlobStream := FZQuery.CreateBlobStream(f, bmRead);"
just crashed, not raise EZNotSupported or so (for example).

[marsupilami]

Which version of Delphi and or / FPC do you use?

[MN7]

XE4. But test from scratch get new info.

Code: Select all

procedure Test;
var
  ZC: TZConnection;
  ZQ: TZQuery;
  BlobStream: TStream;
  B: TBytes;
begin
  ZC := TZConnection.Create(nil);
  try
    ZQ := TZQuery.Create(ZC);
    ZQ.Connection := ZC;

    ZC.Protocol := 'interbase';
    ZC.User := 'SYSDBA';
    ZC.Password := 'masterkey';
    ZC.LoginPrompt := False;
    ZC.Database := 'Firebird_3_0\security3.fdb'; // with full path
    ZC.Connect;

    ZQ.SQL.Text := 'select * from "PLG$USERS"';
    ZQ.Open;

    B := ZQ.FieldByName('PLG$PASSWD').AsBytes;
    ShowMessage(Length(B).ToString);

    BlobStream := ZQ.CreateBlobStream(ZQ.FieldByName('PLG$PASSWD'), bmRead);
    try
      ShowMessage(BlobStream.Size.ToString);
    finally
      BlobStream.Free;
    end;

  finally
    ZC.Free;
  end;
end;

'Length(B).ToString' show 64,
'BlobStream.Size.ToString' show 0.