PeeJays

PJS (pronounced PeeJays) is the Python equivlent to RJS done in Rails. Its still a little wet behind the ears but is already quite useful.

The intention is to have a language native way to get at the Javascript code your client is running. In this case the language is Python and we expose the underlying Prototype primitives, but it would be possible to re-target this whole deal for something like Dojo or MochiKit.

So what does it do? How do you use it? Pretty simple really. Now just to disclaim again, not everything you might want to do works but enough does that I am still going to show this. All the tests and runtime are pure Python with no Zope dependencies, but in the context of these examples I use a handy FSJavascript object which means we have a file in your Plone skin path with a .pjs extension that will render itself as text/javascript. There is an implicit page object available to FSJavascript objects, but if you were doing this by hand if would just be:

page = pjs.JavascriptPage()
...
print page

Ok, now for a real example, or what goes in the ...



There are a number of very standard things we want to do from PJS.

Access an element of the page by its id.

page[id]

Refer to a Javascript variable directly

page.jsvar

and then call methods on those and pass them around.

page['portlet-news'].highlight(delay=1.0)

which might highlight the news portlet for one second when triggered.

We can also do slightly more complex things. For example suppose we have a Tree widget in Javascript and we want to add elements to it that result from doing a query. An AJAX callback to the server might trigger a .pjs file that looks
as follows.



##parameters=of
catalog = context.portal_catalog
ob = catalog(UID=of)[0].getObject()

files = page.files
files.clear()
for title, data in ob.treeFolderContents():
files.addItem(title, data)



Looks just like a regular Python Script in Zope. Parameters tells Zope what to demand from the caller (in this case the AJAX request) and then runs as normal.
This produces the proper Javascript which is returned to the client. All in all its pretty simple. You'd have to understand that files is a Tree object and has a addItem methodand you didn't have to worry about marshalling arguments, or escaping code in some strange cross language way (if you don't know what I mean count your blessings).

There are unit and doc tests for this stuff and its still evolving. Its fun to play with, give it a try.

Update:
This is checked into Bling which can still be had from

http://svn.plone.org/svn/collective/Bling/trunk/