OnUploadFieldRequest event

Applies to

auHTTP component.

Declaration

type

TauHTTPUploadFieldRequest = procedure(Sender: TObject;

FileIndex: Word; UploadStream: TStream;

var FieldName, FileName: String) of object;

procedure OnUploadFieldRequest: TauHTTPUploadFieldRequest;

Description

The OnUploadFieldRequest should be used to put the FieldName, FileName (if required), and data to the stream (UploadStream parameter) for further uploading to the CGI application.

The auHTTP passes to the OnUploadFieldRequest event handler following parameters:

Parameter

Meaning

FileIndex

parameter specifies the index of data-field/file which should be uploaded. (Note: Total number of fields/files which should be uploaded must be specified on call of Upload method. This parameter is the index of file in queue.)

UploadStream

parameter is the empty stream which should be used to write data for uploading. (Use Stream.Write() method to put data to stream, however, since this is TMemoryStream you can use other methods of TMemoryStreams).

FieldName

should be specified in this event handler. This is the name of form field.

FileName

is the optional parameter used to specify local path and filename of uploaded file. It does not transmitted to CGI if empty. Use it only if your CGI application should know the real filename.

Example

procedure TForm1.auHTTP1UploadFieldRequest(Sender: TObject;

FileIndex: Word; UploadStream: TStream; var FieldName, FileName: String);

begin

if FileIndex = 0 then // first file

begin

FieldName := 'img1';

FileName := 'c:\1.jpg';

end

else // second file, if FileIndex = 1

begin

FieldName := 'img2';

FileName := 'c:\2.jpg';

end;

// put file data to stream

(UploadStream as TMemoryStream).LoadFromFile(FileName);

end;

Remarks

Unfortunately the web server itself can NOT receive files by HTTP protocol. For this purpose you should use some intermediate CGI program, in example, written in C, Perl or PHP (or even in Delphi, if you're running Windows server). If you would like to get examples on how to create scripts which can receive files by HTTP protocol, please check out PHP.net (PHP manuals), or www.cgi-resources.com (CGI Resource Index).

Here is an example of PHP script which we are using to upload picture from one our program:

<?php

$picdir  = '/data/www/domains/images.utilmind.com/images/';

if (($index == '') || ($user == '')) die('0'); // not enough parameters POST'ed

$big   = $picdir.$user.$index.'.big'; // big picture

$small = $picdir.$user.$index.'.small'; //thumbnailed image

if ((isset($pic)) && (isset($smallpic))) { // upload (else -- delete it)

copy($pic,      $big)   or die('2'); // store big picture

copy($smallpic, $small) or die('3'); // store thumbnailed image

} else {

if (file_exists($big))   unlink($big); // delete big picture

if (file_exists($small)) unlink($small); //delete thumbnailed image

}

?>

1

If script above does not work for some reason — use $_FILES predefined variable ($_FILES['fieldname']['name'] returns the name of uploaded file, $_FILES['fieldname']['tmp_name'] returns the location where uploaded data temporary stored. Following PHP function moves temporary file to permanent location:

move_uploaded_file($_FILES['field_name']['tmp_name'], $_SERVER['DOCUMENT_ROOT'].'/permanent_location/file.dat') or die('Cannot copy file!');

Here is the link to nice file uploader class in PHP: http://dave.imarc.net/downloads/fileupload.zip

And on Client side we are using following code to POST required data:

procedure TMEMPicUploader.UploadPictureHTTPFieldRequest(Sender: TObject;

FileIndex: Word; UploadStream: TStream; var FieldName,

FileName: String);

const

FieldNames: Array[0..3] of String = ('user', 'index', 'pic', 'smallpic');

var

W, H: Integer;

PicIndexStr: String;

BigImage, SmallImage: TacProportionalImage;

begin

FieldName := FieldNames[FileIndex];

with UploadStream, Client.MyProfile do

case FileIndex of

0: Write(Username[1], Length(Username));

1: begin

PicIndexStr := IntToStr(FPictureIndex);

UploadStream.Write(PicIndexStr[1], Length(PicIndexStr));

end;

else

FileName := Username;

if FileIndex = 2 then

FPicture.Graphic.SaveToStream(UploadStream) // normal picture

else

begin // thumbnailed picture

BigImage := TacProportionalImage.Create(Self);

try

BigImage.Picture.Assign(FPicture);

BigImage.Width := FThumbnailWidth;

BigImage.Height := FThumbnailHeight;

SmallImage := TacProportionalImage.Create(Self);

try

// CREATE THUMBNAILED IMAGE

with BigImage, DrawRect do

begin

W := Right - Left;

H := Bottom - Top;

with SmallImage.Picture.Bitmap do

begin

Width  := W;

Height := H;

end;

SmallImage.Canvas.StretchDraw(Rect(0, 0, W, H), Picture.Graphic);

end;

with TJPEGImage.Create do

try

Assign(SmallImage.Picture.Bitmap);

SaveToStream(UploadStream);

finally

Free;

end;

finally

SmallImage.Free;

end;

finally

BigImage.Free;

end;

end;

end;

end;

If you want to implement uploading of some bulky data to password protected directories, you must know that all uploading data is sent in the headers of HTTP request, before the HTTP server returns the notice that that login information is required. So you must specify Username and Password before uploading, otherwise, if you specifying login information in the OnPasswordRequest event handler, all request headers (all uploading files) will be sent more than once, every time when you set TryAgain parameter of OnPasswordRequest event handler to True.

See also

Upload method and OnUploadProgress event.

File not found.