Over the past few weeks and months I’ve had to cause to write, update and dust off a number of Elgg plugins that I’ve had kicking about. As a good open source citizen I’ve stuck them up on github so others can have a play.

Here they are, in no particular order:

» H5F 1.8

This is an Elgg wrapper around the H5F HTML5 form compatibility library written by Ryan Seddon.

This plugin lets you use handy HTML 5 form extensions like “required” and “placeholder”, as well as some of the new types like <input type=”email” /> in your forms and have them work in older browsers.

» Input Country

Input country is a wrapper around Ben Werdmuller’s phpCountryDropdown tool, and provides a handy dandy country selector input type.

Install this plugin to be able to take advantage of this in your forms.

» Profile Completeness

This plugin provides a view and a widget that displays the completeness of a profile based on the number of fields in the profile that are populated. This list of fields can be extended and modified based on a plugin hook.

I’ve used various incarnations of this plugin now for a number of clients, and since it keeps coming up I’ve tidied it up a bit and stuck it on github.

» Recaptcha

Lastly, here’s an Elgg 1.8 version of a recaptcha plugin I wrote some time ago.

It hooks into the Elgg captcha engine, providing captcha verification for registration and the “request new password” functionality out of the box. It also replaces the input/captcha view.

There are a couple of other recaptcha plugins, but I couldn’t find one which just provided the captcha and nothing else, so here’s mine.

That’s it for now, enjoy!

A new CAPTCHA approachOne thing we try and do when working on a new Elgg feature is – where we can – couple things together as loosely as possible and provide hooks for third party developers to extend Elgg and fill in any blanks.

A good example of where this has been done is the newly introduced Captcha functionality available in the latest nightly testing builds of Elgg.

The Captcha functionality is provided by a module which extends a view called “input/captcha“. This view is blank by default but is used in several places such as user registration and the lost password form.

This means two things; firstly that if a Captcha module isn’t installed or enabled then forms behave normally, and secondly it becomes a trivial matter for third party modules to provide their own Captcha functionality.

This same mechanism is how the URL shortener module works by the way.

Next, the Captcha module extends a number of actions to require a correctly validated Captcha code. This list itself is the product of a plugin hook which returns an array of actions which require Captcha validation:

$actions = array();
$actions = trigger_plugin_hook('actionlist', 'captcha', null, $actions);

...

function captcha_actionlist_hook($hook, $entity_type, $returnvalue, $params)
{
if (!is_array($returnvalue))
$returnvalue = array();

$returnvalue[] = 'register';
$returnvalue[] = 'user/requestnewpassword';

return $returnvalue;
}

The reason why the list of actions is provided this way is twofold, firstly it lets modules use Captcha functionality in their own code through a generic interface, and secondly it is harder to spoof than looking for some marker in the form code.

The Captcha itself injects a server generated token into the form, which together with the user’s response to the characters generated in an image are used to validate that the user is indeed human.

As we can see, Elgg asks to be provided with a Captcha if one is available by including a specific view, but is agnostic as to where (or indeed if) this functionality is supplied.

By using the techniques available to an Elgg programmer I was able to loosely couple the Captcha system to Elgg in such a way that a third party can easily use the same techniques to provide a more advanced module.

Happy coding!

Image “A new Captcha approach” by XKCD

Themes for Elgg are both extremely easy to develop and incredibly powerful. Using themes you can completely change how an Elgg install looks and feels (and even behaves).

Since there has been a fair amount of discussion of themes on the groups, I thought it would be a good idea to write a brief post about it.

Themes use two key Elgg concepts – namely, the plugin architecture and the views system.

By far the easiest and flexible way to make a theme for Elgg is to build it as a plugin. This makes it easy to distribute (since they are self contained) and lets you turn the theme on and off from the admin panel (making the theming process far less invasive!)

What you must first do is create a new plugin directory under /mod (documented here). In a nutshell; create a directory in the name of your theme, a new start.php and a new manifest.xml.

Once you’ve done this you then can start modifying views. This can be done either by extension or by view overriding.

View extension
The first way is to add extra stuff to an existing view via the extend view function from within your start.php’s initialisation function.

For example, the following start.php will add mytheme/spotlight to the already existing site spotlight:

<?php

function mytheme_init()
{
extend_view('page_elements/spotlight','mytheme/spotlight');
}

register_elgg_event_handler('init','system','mytheme_init');

?>

View overriding
The next method is to override an existing theme, completely replacing it with the one provided by your plugin.

View files provided by plugins automatically take precedence over views from the core. So all we have to do to entirely replace the existing spotlight is to create a new spotlight.php in the appropriate hierarchy.

So, if the original view is stored in:

/elgg/views/default/page_elements/spotlight.php

We need to create the file:

/elgg/mod/mytheme/views/default/page_elements/spotlight.php

Now, when we go to the admin panel and activate our theme the spotlight will be replaced by whatever you put in that file. Simple eh?

You can of course do this with any view.

Using a combination of these methods means you can replace the entire look and feel of a site very quickly indeed, although I would suggest that you start slowly since many views do some quite complicated things.