[Zope] RE: Re: Tracking upload of files to Zope

Passin, Tom tpassin at mitretek.org
Fri Oct 3 16:10:22 EDT 2003

[ Gitte Wange]

> Okay - I can see that just dislaying an 'upload in progress' 
> would be the
> best way to do this.
> So I follow this path :-)
> Which leaves me with one last question:
> PageA contains the <form> that has a <input type="file"> element.
> PageB contains a text saying 'Upload in progress ...'
> When that form is submitted, the page won't return until the 
> entire file
> is uploaded (and then the wait text won't get displayed).
> So what I need to do is to make some sort of hidden frame 
> that submits the
> form ?
> How would you do this ? (sorry - it's not obvious for me)

I have done it using (ordinary) frames, and with poup windows.  It
always takes a bit of javascript.  You want to display the message
before starting the upload.  You do not need a hidden frame to submit
the form.  

Say you have decided how you want to display the message.  You can do
something like this -

function displayMessage() {//show message ...}
function upload() {
<form name='yourform' action='....' encoding='...'>
   <input type='button' value='Upload File' onClick='upload()'>

This leaves you with two things to work out -

1) How to display the message
2) How to cancel the message display.

If you display the message within the page, it will automatically go
away when the file finishes uploading.  That takes care of 2)  so that
would be the easiest thing to do.

You could -

1) Display the message in an iframe.
2) Display the message in a text input box.
3) Display the message in an existing element in the HTML page.
4) Display the message in a popup window and close it using the onUnload
event when the upload finally finishes.

If it were me, I would create a div element for the message and hide it
using the CSS instruction display:none.  I would use the DOM method
getElementById() to get a reference to it and change the style to
display:block when I wanted to show it.

However, this will not work with older browsers (like NS4) or lynx.  I
would not care about that, but you may very well care.  With lynx, you
really cannot do much, but with NS4 yuu would just have to use a
slightly different approach to locate the element you are interested in.
My preferred approach should work in IE5+, Mozilla, NS6+, and (I think)
Opera 7+.  Obviously the browser needs to support the DOM, otherwise you
have to go to browser-specific methods.

That leads to the iframe.  For browsers that support the iframe, you can
just write into an element in the iframe using document.write(), or have
it load a static page from the server.

Let us know if you need more information.


Tom P

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