Extension Cookbook

Common things developers ask “how do I…” - with the smallest working snippet for each. Every recipe uses public hooks; nothing here forks the source.

Add a field to the apply form

You want candidates to fill in (say) a “LinkedIn URL” when applying.

// 1. Render the input inside the apply panel.
add_action( 'wcb_application_form_fields', function ( $job_id ) {
    ?>
    <label class="wcb-form-label">
        <span><?php esc_html_e( 'LinkedIn URL', 'my-addon' ); ?></span>
        <input type="url" name="my_addon_linkedin" class="wcb-field" />
    </label>
    <?php
});

// 2. Allow the field through the apply endpoint.
add_filter( 'wcb_application_form_fields_groups', function ( $groups, $job_id ) {
    $groups['my_addon'] = array(
        'fields' => array(
            'linkedin' => array( 'type' => 'url', 'sanitize' => 'esc_url_raw' ),
        ),
    );
    return $groups;
}, 10, 2 );

// 3. Read the saved value later - it's stored as `_wcb_application_field_linkedin`.
$url = get_post_meta( $app_id, '_wcb_application_field_linkedin', true );

Add a column to the admin applications table

add_filter( 'manage_wcb_application_posts_columns', function ( $cols ) {
    $cols['my_score'] = __( 'Score', 'my-addon' );
    return $cols;
});

add_action( 'manage_wcb_application_posts_custom_column', function ( $col, $post_id ) {
    if ( 'my_score' === $col ) {
        echo (int) get_post_meta( $post_id, '_my_score', true );
    }
}, 10, 2 );

Notify Slack when a job is posted

add_action( 'wcb_job_created', function ( $job_id, $request ) {
    $title = get_the_title( $job_id );
    wp_remote_post( SLACK_WEBHOOK_URL, array(
        'body' => wp_json_encode( array(
            'text' => sprintf( 'New job posted: *%s*', $title ),
        ) ),
        'headers' => array( 'Content-Type' => 'application/json' ),
        'blocking' => false,
    ));
}, 10, 2 );

Add a tab to the Settings page

add_filter( 'wcb_settings_tabs', function ( $tabs ) {
    $tabs['my_addon'] = __( 'My Addon', 'my-addon' );
    return $tabs;
});

add_action( 'wcb_settings_tab_my_addon', function () {
    settings_fields( 'my_addon_group' );
    do_settings_sections( 'my_addon_group' );
    submit_button();
});

Override the credit cost for a specific board

add_filter( 'wcb_board_credit_cost', function ( $cost, $board_id ) {
    if ( get_option( 'my_addon_premium_board' ) === $board_id ) {
        return 5; // Override the normal cost
    }
    return $cost;
}, 10, 2 );

Inject a step into the post-a-job wizard

The 4-step wizard fires wcb_job_form_step1_fields … wcb_job_form_step4_preview actions inside each step’s container. Adding a fifth step takes a JS-side hook too - but injecting fields into an existing step is trivial:

add_action( 'wcb_job_form_step3_fields', function () {
    ?>
    <div class="wcb-form-field">
        <label class="wcb-form-label">
            <?php esc_html_e( 'Industry sub-category', 'my-addon' ); ?>
        </label>
        <select name="my_addon_subcat">
            <option value="frontend">Frontend</option>
            <option value="backend">Backend</option>
        </select>
    </div>
    <?php
});

Add a column to the REST jobs response

add_filter( 'wcb_rest_prepare_job', function ( $row, $post ) {
    $row['my_remote_friendly'] = (bool) get_post_meta( $post->ID, '_remote_friendly', true );
    return $row;
}, 10, 2 );

This propagates everywhere the jobs API is consumed - the listings block, the single-job page, third-party integrations.

Disable a built-in feature

Most Pro features are gated by wcb_pro_*_enabled filters. To turn off resume builder for a specific role:

add_filter( 'wcb_pro_resumes_enabled', function ( $enabled ) {
    if ( current_user_can( 'wcb_employer' ) ) {
        return false; // Hide resume tab from employers
    }
    return $enabled;
});

Customize the “Buy Credits” link

Different gateways for different user segments:

add_filter( 'wcb_credit_purchase_url', function ( $url ) {
    if ( current_user_can( 'wcb_employer_premium' ) ) {
        return '/premium-credits/';
    }
    return $url;
});

Restrict the boards dropdown by user role

add_filter( 'wcb_board_options_for_employer', function ( $options, $user_id ) {
    if ( ! user_can( $user_id, 'wcb_post_to_premium_boards' ) ) {
        // Drop any board whose id is in the "premium" list.
        $premium_ids = (array) get_option( 'my_premium_board_ids', array() );
        $options = array_filter( $options, fn( $o ) => ! in_array( (int) $o['id'], $premium_ids, true ) );
    }
    return $options;
}, 10, 2 );

(Pro’s BP-groups integration uses this same filter to drop boards whose linked BuddyPress group the user is not a member of.)

Add a custom transactional email

The email registry holds email objects, not config arrays. Each one extends WCB\Modules\Notifications\AbstractEmail, declares its identity, and wires its own trigger hook in boot(). Register the object through the wcb_registered_emails filter and it appears automatically in Settings -> Emails (subject override, enable/disable toggle, and the send log all come for free).

use WCB\Modules\Notifications\AbstractEmail;

class My_Welcome_Email extends AbstractEmail {

    public function get_id(): string {
        return 'my_addon_welcome';
    }

    public function get_title(): string {
        return __( 'Welcome to the board', 'my-addon' );
    }

    public function get_recipient(): string {
        return __( 'New candidates', 'my-addon' );
    }

    public function get_default_subject(): string {
        return __( 'Welcome to our job board', 'my-addon' );
    }

    public function boot(): void {
        // Trigger off any Career Board action hook.
        add_action( 'wcb_candidate_registered', array( $this, 'handle' ), 10, 2 );
    }

    public function handle( int $user_id, $request ): void {
        $user = get_userdata( $user_id );
        if ( ! $user ) {
            return;
        }
        // send() respects the per-template enable toggle and writes the log row.
        $this->send( $user->user_email, array( 'name' => $user->display_name ), $user_id );
    }
}

add_filter( 'wcb_registered_emails', function ( array $emails ): array {
    $emails[] = new My_Welcome_Email();
    return $emails;
});

The base class gives you is_enabled(), get_subject() (with the admin override), and the protected send( $to, $vars, $user_id ) helper that dispatches and logs. Read modules/notifications/emails/class-email-job-approved.php for a complete working example.

Where to find the rest

Read 02-hooks-reference.md for the full inventory. For anything not covered by a hook, the next step is to extend a Career Board class directly - see 03-rest-api.md for the REST controller base class and the WP-CLI section in 04-wp-cli.md for the CLI base class.