WordPress ACF how to filter a textarea field content

Question

I'm building a WordPress theme that uses the Advanced Custom Fields (ACF plugin). I have the following function via functions.php:

function filter_p_tags( $content ) {
    $content = str_replace( '<p>','<p class="custom__class">', $content );
    return $content;
}
add_filter('the_content', 'filter_p_tags');
add_filter('acf_the_content','filter_p_tags');

The <p> tags via posts and pages are successfully being replaced with <p class="custom__class">. However, my ACF fields are not being filtered. What am I doing wrong here?

It's worth mentioning that the ACF fields in question belong to an options page. Here's how an option field looks within one of my templates.

<?php the_field( 'text', 'option' ); ?>

Answer 1

If your ACF field is a textarea, then you would want to use acf/format_value/type=textarea filter hook instead of using acf_the_content which would be applied on wysiwyg.

add_filter('acf/format_value/type=textarea', 'filter_p_tags_acf', 10, 3);

So your entire code would be something like this:

add_filter('the_content', 'filter_p_tags');

function filter_p_tags( $content ) {

    $content = str_replace( '<p>','<p class="custom__class">', $content );

    return $content;

}

add_filter('acf/format_value/type=textarea', 'filter_p_tags_acf', 10, 3);

function filter_p_tags_acf( $value, $post_id, $field ) {

    $value = str_replace( '<p>','<p class="custom__class">', $value );

    return $value;

}

---

Another way of doing this

Alternatively, as you suggested, we could use acf/format_value/key={$key} filter hook instead of using acf/format_value/type=textarea. Like so:

add_filter('acf/format_value/key=field_abc123456', 'filter_p_tags_acf', 10, 3);

function filter_p_tags_acf( $value, $post_id, $field ) {

    $value = str_replace( '<p>','<p class="custom__class">', $value );

    return $value;

}