BuddyPress.org

Hi Venutis! Thank you for the tip 🙂

But I found this code online created by a fellower named Brajesh Singh that worked very well. I just pasted it into my child theme’s functions.php

//////////////////////////////////////////////////////////////////
// BuddyPress send private message button
//////////////////////////////////////////////////////////////////

/**
 * Get a link to send PM to the given User.
 *
 * @param int $user_id user id.
 *
 * @return string
 */
function buddydev_get_send_private_message_to_user_url( $user_id ) {
    return wp_nonce_url( bp_loggedin_user_domain() . bp_get_messages_slug() . '/compose/?r=' . bp_core_get_username( $user_id ) );
}

/**
 * Shortcode [bp-pm-button username=optional_some_user_name]
 *
 * @param array $atts shortcode attributes.
 * @param string $content content.
 *
 * @return string
 */
function buddydev_private_message_button_shortcode( $atts, $content = '' ) {
    // User is not logged in.
    if ( ! is_user_logged_in() ) {
        return '';
    }
 
    $atts = shortcode_atts( array(
        'user_id'   => '',
        'username'  => '',
        'label'     => 'Send Private Message',
    ), $atts );
 
    $user_id = absint( $atts['user_id'] );
    $user_login = $atts['username'];
 
    // if the username is given, override the user id.
    if ( $user_login ) {
        $user = get_user_by( 'login', $user_login );
        if ( ! $user ) {
            return '';
        }
        $user_id = $user->ID;
    }
 
    if ( ! $user_id ) {
        if ( ! in_the_loop() ) {
            return '';
        }
 
        $user_id = get_the_author_meta('ID' );
    }
    // do not show the PM button for the user, if it is aimed at them.
    if ( bp_loggedin_user_id() === $user_id ) {
        return '';
    }
 
    // if we are here, generate the button.
    $button = sprintf('<a href="%1$s">%2$s</a>', buddydev_get_send_private_message_to_user_url( $user_id ), $atts['label'] );
 
    return $button . $content;
}
 
add_shortcode( 'bp-pm-button', 'buddydev_private_message_button_shortcode' );