Hello world¶

This tutorial shows you how to create a new plugin that consists of a new page with the text “Hello world” on it.

Before anything else, you need to install Elgg.

In this tutorial we will pretend your site’s URL is https://elgg.example.com.

First, create a directory that will contain the plugin’s files. It should be located under the mod/ directory which is located in your Elgg installation directory. So in this case, create mod/hello/.

Manifest file¶

Elgg requires that your plugin has a manifest file that contains information about the plugin. Therefore, in the directory you just created, create a file called manifest.xml and copy this code into it:

<?xml version="1.0" encoding="UTF-8"?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
    <name>Hello world</name>
    <id>hello</id>
    <author>Your Name Here</author>
    <version>0.1</version>
    <description>Hello world, testing.</description>
    <requires>
        <type>elgg_release</type>
        <version>2.0</version>
    </requires>
</plugin_manifest>

This is the minimum amount of information in a manifest file:

<name> is the display name of the plugin
<id> must be the same as the directory you just created
<requires> must include which version of Elgg your plugin requires
<author>, <version> and <description> should have some appropriate values but can be filled freely

Initializer¶

Next, create start.php in the mod/hello/ directory and copy this code into it:

<?php

elgg_register_event_handler('init', 'system', 'hello_world_init');

function hello_world_init() {

}

The above code tells Elgg that it should call the function hello_world_init() once the Elgg core system is initiated.

Registering a route¶

The next step is to register a route which has the purpose of handling request that users make to the URL https://elgg.example.com/hello.

Update elgg-plugin.php to look like this:

<?php

return [
    'routes' => [
                'default:hello' => [
                        'path' => '/hello',
                        'resource' => 'hello',
                ],
        ],
];

This registration tells Elgg that it should call the resource view hello when a user navigates to https://elgg.example.com/hello.

View file¶

Create mod/hello/views/default/resources/hello.php with this content:

<?php

$body = elgg_view_layout('content', [
    'title' => 'Hello world!',
    'content' => 'My first page!',
    'filter' => '',
]);

echo elgg_view_page('Hello', $body);

The code creates an array of parameters to be given to the elgg_view_layout() function, including:

The title of the page

The contents of the page

Filter which is left empty because there’s currently nothing to filter

This creates the basic layout for the page. The layout is then run through elgg_view_page() which assembles and outputs the full page.

Last step¶

Finally, activate the plugin through your Elgg administrator page: https://elgg.example.com/admin/plugins (the new plugin appears at the bottom).

You can now go to the address https://elgg.example.com/hello/ and you should see your new page!