Add link from page reference fields - Module example

PageReferenceLink.module

<?php

/**
 * ProcessWire PageReferenceLink
 *
 * @author Soma philipp(at)urlich.ch
 *
 * 
 * ProcessWire 2.x 
 * Copyright (C) 2010 by Ryan Cramer 
 * Licensed under GNU/GPL v2, see LICENSE.TXT
 * 
 * http://www.processwire.com
 * http://www.ryancramer.com
 *
 */

class PageReferenceLink extends WireData implements Module {

	/**
	 * getModuleInfo is a module required by all modules to tell ProcessWire about them
	 *
	 * @return array
	 *
	 */
	public static function getModuleInfo() {

		return array(
			'title' => 'Page Reference Link', 
			'version' => 001, 
			'summary' => 'Module to prepend link(s) to page(s) selected in page reference fields.',
			'href' => '',
			'singular' => true,
			'autoload' => true
			);
	}


	public function init() {

		$this->addHookAfter("InputfieldPageListSelectMultiple::render", $this, "renderMultiple");

		$this->addHookAfter("InputfieldPageListSelect::render", $this, "renderSingle");

		$this->addHookAfter("InputfieldPageListSelect::render", $this, "findRelated");

	}

	public function renderMultiple($event) {

		// returns the event object in this case the inputfield
		$inputfield	= $event->object;
		$fname		= $inputfield->name;

		// if not on desired field name(s) we don't go any further
		if(!($fname == "selec_page_image" 
			|| $fname == "selec_page_image_1"
			// enter more here
			)) return;
		
		// stop if there's no value
		if($inputfield->value == null) return;

		$out = '';
		
		foreach($inputfield->value as $id){
			$p = $this->pages->get("id=$id,include=hidden");
			$url = $this->config->urls->admin . "page/edit/?id=$p->id";
			$out .= "<li><a href='$url'><span class='ui-icon ui-icon-pencil'></span>{$p->title}</a> ($p->path)</li>";
		}
		// return output
		$descr = "<div class='ui-widget-content' style='clear:both;margin-bottom:1em;padding:0 1em 1em;'><p class='description'>Edit links to the pages selected</p>";
		$event->return = $event->return . $descr . "<ul class='PageReferenceLink_list' style='clear:float'>".$out."</ul></div>" ;
	}


	public function renderSingle(HookEvent $event) {

		// returns the event object in this case the inputfield
		$inputfield	= $event->object; 
		$fname		= $inputfield->name;

		// if not on desired field we wont go any further
		if(!($fname == "select_architect"
			|| $fname == "some_page_field"
			// enter more here
			)) return;

		// if nothing there go return
		if(count($inputfield->value) == 0) return;
		
		$out = '';

		// ok still here? lets get the page selected
		$p = $this->pages->get("id=$inputfield->value->id,include=hidden");
		
		// and create the link for output
		$url = $this->config->urls->admin . "page/edit/?id=$p->id";
		$out .= "<li><a href='$url'><span class='ui-icon ui-icon-pencil'></span>{$p->title}</a> ($p->path)</li>";
		
		// return the string prepended to the inputfield output
		$descr = "<div class='ui-widget-content' style='clear:both;margin-bottom:1em;padding:0 1em 1em;'><p class='description'>Edit link to the page selected</p>";
		$event->return = $event->return . $descr . "<ul class='PageReferenceLink_list' style='clear:float'>".$out."</ul></div>";
	}

	/**
	 * find related pages that are also linked to the page
	 *
	 *
	 */
	public function findRelated(HookEvent $event) {

		// returns the event object in this case the inputfield
		$inputfield		= $event->object; 
		$fname			= $inputfield->name;
		$field_filter 	= "select_architect";

		// if not on desired field we wont go any further
		if(!($fname == $field_filter)) return;

		// if nothing there go return
		// if(count($inputfield->value) == 0) return;
		
		$out = '';

		// get current page edited
		$epId = wire("input")->get->id;
		$edited_page = wire("pages")->get($epId);

		// search for a page backlinked to this currently being edited
		$result = wire("pages")->find("$field_filter=$edited_page,include=hidden");
		
		// if any page(s) found 
		if(count($result)) {
			// render them in a list
			foreach($result as $res){
				// and create the link for output
				$url = $this->config->urls->admin . "page/edit/?id=$res->id";
				$out .= "<li><a href='$url'><span class='ui-icon ui-icon-pencil'></span>{$res->title}</a> ($res->path)</li>";
			}

		} else {
			// if none found return a message that none was found
			$out .= "<li><span class='error'>No related page found linking to this page!</span></li>";
		}
		// return the string prepended to the inputfield output
		$descr = "<div class='ui-widget-content' style='clear:both;margin-bottom:1em;padding:0 1em 1em;'><p class='description'>Page that refer to this page</p>";
		$event->return = $event->return . $descr . "<ul class='PageReferenceLink_list'>".$out."</ul></div>";
	}
}