Event-driven programming example with PHP5 and Midgard2

evented.php

<?php
// Open Midgard connection
$config = new midgard_config();
$config->read_file_at_path(ini_get('midgard.configuration_file'));

// Do stuff when we get a DB connection
midgard_connection::get_instance()->connect('connected', function($connection) {
    echo "Connected, Midgard version " . mgd_version() . "\n";
});

midgard_connection::get_instance()->open_config($config);

// Whenever an article is updated we want to know about it
midgard_object_class::connect_default('org_midgardproject_news_article', 'action-updated', function($object) {
    echo $object->title . " was updated\n";
});

// Query for articles
$q = new midgard_query_select(
    new midgard_query_storage('org_midgardproject_news_article')
);
$q->add_order(new midgard_query_property('metadata.created'), SORT_DESC);

// When query starts executing we may add constraints to it
$q->connect('execution-start', function($executor) {
    // Only query articles with a title that starts with "Hello"
    $executor->set_constraint
    (
        new midgard_query_constraint
        (
            new midgard_query_property('title'),
            'LIKE',
            new midgard_query_value('Hello%')
        )
    );
});

// When query is done, we may do something with the results
$q->connect('execution-end', function($executor) {
    // Increase the score of each queried article by one
    array_walk($executor->list_objects(), function($object) {
        $object->metadata->score++;
        $object->update();
    });
});

$q->execute();