Save_post acf data not updating category of post type

Question

i am trying to assign multiple categories to my Custom Post Type using advanced custom field named 'cat'. But there is nothing saving to my categories. Any help?

<?php
// Add an action to run on post save
add_action( 'save_post', 'set_genre_on_save' );
function set_genre_on_save( $post_id ){
    // Check the post type
    if (is_single('hvm')) {
        // Get the custom field data
        $custom_field_data = get_post_custom( $post_id );
        // Check if there is any category entered in the metabox
        if (isset($custom_box_data['cat'])) {
            // Save the data (separated by comma) into an array
            $genre_array = explode( ',', $custom_box_data['cat'] );
            //Set the array values to lower case
            foreach ($genre_array as $genre){
                $genre = strtolower($genre);
            }
            // Set the categories for these genres
            wp_set_object_terms( $post_id, $genre_array, 'category' );
        }
    }
}
?>

Answer 1

You can not use is_single() conditional tag here.

You can check the type of post in the function this way:

add_action( 'save_post', 'set_genre_on_save', 20, 3 );
function set_genre_on_save( $post_id, $post, $update ) {
    if ($post->post_type != 'hvm')
        return;

    // ...
}  

You can also attach the function to the action hook save_post_{post_type}, which is triggered only for the {post_type} type. Then there is no need to check the type of post inside the function.

add_action( 'save_post_hvm', 'set_genre_on_save', 20, 3 );