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Home » Newsletter » July 2009

By Suraj C. B.

TBlobStream is used to read or write to a BLOB field in a dataset. If you can write a PDF document to a BLOB field, then you can store the PDF document in an RDBMS database.

PDFtoolkit allows you to save a PDF document to a memory stream. You can then use the memory stream to copy the PDF document to a TBlobStream instance. The code snippet below shows you how.

procedure TForm1.SavetoBlobClick(Sender: TObject);
 var
   blob: TBlobStream;
   TempStrm: TMemoryStream;
 begin
  // Create a blob stream for writing 
  blob := YourDataset.CreateBlobStream(
               YourDataset.FieldByName('YOUR_BLOB_FIELD_NAME'),
               bmWrite);
   try
     // Move to the beginning of the blob stream for read operations
     blob.Seek(0, soFromBeginning);
     // Create a memory stream
     TempStrm := TMemoryStream.Create;
     // Load a PDF document
     gtPDFDocument1.LoadFromFile('C:\Input.pdf');

     // Steps for modifying the PDF omitted.

     // Save the PDF document to the stream 
     gtPDFDocument1.SaveToStream(TempStrm);

     // Move to the beginning of the memory stream for read operations
     TempStrm.Position := 0;
     // Copy the stream to the blob
     try
       blob.CopyFrom(TempStrm, TempStrm.Size)
     finally
       TempStrm.Free
     end;
   finally
     blob.Free
   end;
end;