add_filter priority problem

Question

I'm using basic user avatars for use local avatar in wordpress. And i have a simple function in my functions.php for getting avatar direct link. My problem is if i use get_avatar function in my functions php it returns gravatar img but if i use get_avatar function in my frontend pages it returns local avatars. Here is plugins's code

public function __construct() {

    // Text domain
    $this->load_textdomain();

    // Actions
    add_action( 'admin_init',                array( $this, 'admin_init'               )        );
    add_action( 'show_user_profile',         array( $this, 'edit_user_profile'        )        );
    add_action( 'edit_user_profile',         array( $this, 'edit_user_profile'        )        );
    add_action( 'personal_options_update',   array( $this, 'edit_user_profile_update' )        );
    add_action( 'edit_user_profile_update',  array( $this, 'edit_user_profile_update' )        );
    add_action( 'bbp_user_edit_after_about', array( $this, 'bbpress_user_profile'     )        );

    // Shortcode
    add_shortcode( 'basic-user-avatars',     array( $this, 'shortcode'                )        );

    // Filters
    add_filter( 'get_avatar',                array( $this, 'get_avatar'               ), 10, 5 );
    add_filter( 'avatar_defaults',           array( $this, 'avatar_defaults'          )        );
}

public function get_avatar( $avatar = '', $id_or_email, $size = 96, $default = '', $alt = false ) {

    // Determine if we recive an ID or string
    if ( is_numeric( $id_or_email ) )
        $user_id = (int) $id_or_email;
    elseif ( is_string( $id_or_email ) && ( $user = get_user_by( 'email', $id_or_email ) ) )
        $user_id = $user->ID;
    elseif ( is_object( $id_or_email ) && ! empty( $id_or_email->user_id ) )
        $user_id = (int) $id_or_email->user_id;

    if ( empty( $user_id ) )
        return $avatar;

    $local_avatars = get_user_meta( $user_id, 'basic_user_avatar', true );

    if ( empty( $local_avatars ) || empty( $local_avatars['full'] ) )
        return $avatar;

    $size = (int) $size;

    if ( empty( $alt ) )
        $alt = get_the_author_meta( 'display_name', $user_id );

    $author_class = is_author( $user_id ) ? ' current-author' : '' ;
    $avatar       = "<img alt='" . esc_attr( $alt ) . "' src='" . $local_avatars['full'] . "' class='avatar avatar-{$size}{$author_class} photo' height='{$size}' width='{$size}' />";

    return apply_filters( 'basic_user_avatar', $avatar );
}

I tried to use lower priority in add_filter('get_avatar') but if i use lower priority plugis not working. Probably because apply_filters in return statement. But i don't know what is problem exactly. How can i fix this problem? Thanks

Answer 1

1. The get_avatar filter accepts 6 parameters, not 5.

2. The $id_or_email can also be an instance of WP_Post, WP_User or a md5 hash string. So it's better to extract $user_id like this:

 if ( is_numeric( $id_or_email ) ) {
     $user_id = $id_or_email;
 } elseif ( is_string($id_or_email) ) {
     if ( is_email($id_or_email) ) {
         $user = get_user_by('email', $id_or_email);
         $user_id = $user->ID;
     } else { // md5 hash string
         // Do something.
     }
 } elseif ( is_object($id_or_email) ) {
     if ($id_or_email instanceof \WP_User) {
         $user_id = $id_or_email->ID;
     } elseif ($id_or_email instanceof \WP_Post) {
         $user_id = $id_or_email->post_author;
     } else {
         $user_id = $id_or_email->user_id;
     }
 } else {
     return $avatar;
 } 

3. Make sure the get_user_meta( $user_id, 'basic_user_avatar', true ) return something. If nothing is returned, default $avatar will be used.