Advanced Custom Fields

Integrate Algolia Search for WordPress with Advanced Custom Fields.

Introduction

The Advanced Custom Fields plugin is a very popular plugin that allows you to create your custom fields directly from the admin section of your WordPress website.

On this page we will give some examples on how to push these custom fields to Algolia, make them searchable and have them impact the ranking of your results.

If you haven't read the basics of extending this plugin, you should read that first.

To get an in depth overview of the methods introduced by Advanced Custom Fields, please read the Official Advanced Custom Fields documentation.

Push custom fields to Algolia

In the following example, we will add the bio field to the posts that have a post type of speaker.

Here we assume you have a custom post type speaker which is not natively available in WordPress.

We add the bio attribute to both searchable_posts and posts indices.

<?php

add_filter( 'algolia_post_shared_attributes', 'my_post_attributes', 10, 2 );
add_filter( 'algolia_searchable_post_shared_attributes', 'my_post_attributes', 10, 2 );

/**
 * @param array   $attributes
 * @param WP_Post $post
 *
 * @return array
 */
function my_post_attributes( array $attributes, WP_Post $post ) {
    if ( 'speaker' !== $post->post_type ) {
        // We only want to add an attribute for the 'speaker' post type.
        // Here the post isn't a 'speaker', so we return the attributes unaltered.
        return $attributes;
    }

    // Get the field value with the 'get_field' method and assign it to the attributes array.
    // @see https://www.advancedcustomfields.com/resources/get_field/
    $attributes['bio'] = get_field( 'bio', $post->ID );

    // Always return the value we are filtering.
    return $attributes;
}

Make custom fields searchable

In this example we make sure that the bio attribute we pushed earlier is taken into account in the Algolia relevancy algorithm.

Here we only alter the settings of the posts_speaker index because in the searchable_posts index not all posts have the bio attribute, so basing the relevancy on that field might lead to results that are difficult to understand for the end users.

In this example, we also ask for Algolia to return a snippet of 50 chars from the bio attribute along with the record. This will allow you to display a relevant snippet of the bio attribute to your end users. The snippet is dynamically generated by the Algolia engine to show the most relevant part of the attribute regarding the current user's request.

<?php

add_filter( 'algolia_posts_speaker_index_settings', 'my_posts_index_settings' );
// We could also have used a more general hook 'algolia_posts_index_settings',
// but in that case we would have needed to add a check on the post type
// to ensure we only adjust settings for the 'speaker' post_type.

/**
 * @param array $settings
 *
 * @return array
 */
function my_posts_index_settings( array $settings ) {

    // Make Algolia search the 'bio' field when searching for results.
    // Using ordered instead of unordered will make words matching in the beginning of the attribute score higher.
    // @see https://www.algolia.com/doc/api-reference/api-parameters/searchableAttributes/
    $settings['searchableAttributes'][] = 'unordered(bio)';

    // Make Algolia return a pre-computed snippet of 50 chars as part of the result set.
    // @see https://www.algolia.com/doc/api-reference/api-parameters/#highlighting-snippeting
    $settings['attributesToSnippet'][] = 'bio:50';

    // Always return the value we are filtering.
    return $settings;
}

Integrate custom fields in your custom ranking

You can integrate your custom metrics in the ranking algorithm of Algolia. That way, you can provide your end users with results ranked according to your business requirements.

In this example, let's say you are a company selling videos on your WordPress website. Your website is tracking the number of views of each video in a custom attribute called view_count.

In this example we will show you how to add the view_count attribute to the custom ranking. The idea being that if several videos are considered a good match regarding the current user's search query, we will order the results based on the view_count. Read more about custom ranking here: https://www.algolia.com/doc/guides/managing-results/must-do/custom-ranking/#custom-ranking

Note that you can add as many attributes to the custom ranking as you want. The order in which the attributes appear in the custom ranking matters as under the hood, Algolia uses a Tie Breaking algorithm. Read more about it here: https://www.algolia.com/doc/guides/managing-results/must-do/custom-ranking/#algolias-ranking-strategy

Here we assume you already made it so that the view_count is pushed to the posts_video index as explained in the 'push custom fields to Algolia' section.

<?php

add_filter( 'algolia_posts_video_index_settings', 'my_video_index_settings' );
// We could also have used a more general hook 'algolia_posts_index_settings',
// but in that case we would have needed to add a check on the post type
// to ensure we only adjust settings for the 'video' post_type.

/**
 * @param array $settings
 *
 * @return array
 */
function my_video_index_settings( array $settings ) {

    // By default, the plugin uses 'is_sticky' and the 'post_date' in the custom ranking.
    // Here we retrieve the custom ranking so that we can alter it with more control.
    $customRanking = $settings['customRanking'];

    // We add our custom ranking rule at the beginning of the rules so that
    // it is the first one considered in the algorithm.
    array_unshift( $customRanking, 'desc(views_count)' );

    // We override the initial custom ranking rules.
    $settings['customRanking'] = $customRanking;


    // Always return the value we are filtering.
    return $settings;
}