[whatwg] What should the value attribute be for multi-file upload controls in WF2?

Fri Jun 20 06:44:01 PDT 2008

Adele Peterson wrote:
> I'm looking at the Web Forms 2 specification for the multi-file 
> upload control that uses the min/max attributes.  When multiple files 
> are selected, its unclear what the value attribute should contain.

Assuming you're referring to the value DOM attribute, not the value="" 
content attribute, It seems to be unclear what the value should contain 
even when there's only a single file selected.

I did some testing to see what each returned.  All tests use this markup 
to obtain the value, using the Live DOM Viewer:

<!DOCTYPE html>
<input type="file" id="test" size=100>
<input type=button onclick="w(document.getElementById('test').value);" 
value="Read Value...">

http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0D%0A%3Cinput%20type%3D%22file%22%20id%3D%22test%22%20size%3D100%3E%0D%0A%3Cinput%20type%3Dbutton%20onclick%3D%22w(document.getElementById('test').value)%3B%22%20value%3D%22Read%20Value...%22%3E

In each one, I selected a file named test.txt from within my home or My 
Documents directory.  These are the vaules returned in each browser:

Windows browsers:
IE 8:         test.txt
IE 7 mode:    test.txt
Firefox 2:    D:\My Documents\test.txt
Firefox 3:    test.txt
Opera 9.5:    C:\fake_path\test.txt
Safari 3.1.1: D:\My Documents\test.txt

Mac browsers:
Firefox 3:    test.txt
Opera 9.5:    C:\fake_path\test.txt
Safari 4 (Developer Preview): /Users/lachlanhunt/test.txt

> It could contain just the first filename, or a comma separated list 
> of all of the filenames.  I think it will be useful though to add 
> something about this in the specification for consistency.

Opera 9.5 supports multiple file selection when a max="" attribute is 
set to a value greater than 1.  It currently only returns the fake path 
of the first file, as shown above.  However, the control displays to the 
user the real paths of all files selected as quoted strings separated by 
semi-colons. e.g.

"/Users/lachlanhunt/test.txt";"/Users/lachlanhunt/other.txt"

Since Both Firefox 3 and IE 8 only return the file name, and Opera 9.5 
refuses to return the real path anyway, maybe we should define that when 
there's only a single file selected, it returns just the file name. When 
there are multiple files selected, would a string containing the file 
names, each surrounded by quotes and separated by semi-colons work?

e.g. "test.txt";"other.txt"

There's a small problem with that too, because we would need a way to 
handle file names that contained quote marks, which is possible on Mac 
and Linux, but not on Windows.

But it really depends what use cases we need to address.  Do authors 
ever actually obtain the file name using JavaScript for anything?  If 
so, what for?  With multiple file selection, is it likely they would 
want to inspect each individual file name for anything, in which case, 
should we find a way to make it easier to obtain individual file names?

-- 
Lachlan Hunt - Opera Software
http://lachy.id.au/
http://www.opera.com/