I added this link beside the out-of-stock associated product:
http://localhost/mysite/index.php/productalert/add/stock/product_id/[associated_product_id]/uenc/[any_key]/
For e.g.
http://localhost/mysite/index.php/productalert/add/stock/product_id/17/uenc/MTM0MzcyMDk0Mw==/
It does my job.
Only thing is, after successfully adding the alert record, it redirects to home page, instead of same page as in normal case.
This is due to [any_key], if we could somehow encrypt current page url [the any_key] just like magento does, we can have it redirect to same page also, after successful saving of alert record.
Any ideas?
Thanks
Ok I got it finally!
The uenc key [any_key] is actually base64 encoding of current url.
So with the help of https://github.com/carlo/jquery-base64, I did:
var encodedUrl = $.base64.encode(window.location);
var redirectTo = 'http://localhost/mysite/index.php/productalert/add/stock/product_id/[associated_product_id]/uenc/' + encodedUrl + '/';
Hope this helps!