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III.10.12 Using .vuh files for pretty urls

.Vuh files are special cases of .tcl files, used for rewriting incoming urls. We can use a vuh file to prettify the uri for our notes. Instead of note-edit?item_id=495, we can use note/495. To do this, we will need a new .vuh file for redirection and we will need to change the referring links in note-list. First, add the vuh:

[$OPENACS_SERVICE_NAME $OPENACS_SERVICE_NAME]$ cd /var/lib/aolserver/$OPENACS_SERVICE_NAME/packages/myfirstpackage/www
[$OPENACS_SERVICE_NAME www]$ emacs note.vuh

Paste this into the file:

# Transform requests of type: a/b
# into this internal request: A?c=b
# for example, note/495 > note-edit?item_id=496
# a: base name of this .vuh file
# b: from the request
# A: hard-coded
# C: hard-coded

set query [ad_conn url]

set request [string range $query [expr [string last / $query] + 1] end]

rp_form_put item_id $request

set internal_path "/packages/[ad_conn package_key]/www/note-edit"

rp_internal_redirect $internal_path

We parse the incoming request and treat everything after the final / as the item id. Note that this simple redirection will lose any additional query parameters passed in. Many OpenACS objects maintain a pretty-name, which is a unique, human-readable string, usually derived from title, which makes an even better 'pretty url' than a numeric id; this requires that your display page be able to look up an item based on pretty id.

We use rp_form_put to store the item id in the internal register that the next page is expecting, and then redirects the request in process internally (ie, without a browser refresh).

Next, modify note-list so that its link is of the new form.:

[$OPENACS_SERVICE_NAME www]$ emacs ../lib/note-edit.tcl
db_multirow  -extend {
    } notes notes_select {
	select ci.item_id,
        from   cr_items ci,
               mfp_notesx n
        where  n.revision_id = ci.live_revision
    } {
	set edit_url [export_vars -base "note/$item_id"]
	set delete_url [export_vars -base "note-delete" {item_id}]

You may also need to change some of the links in your package. Commonly, you would use ad_conn package_url to build the URL. Otherwise, some of your links may be relative to the virtual directory (note/) instead of the actual directory that the note is being served from.