我正在开发一个使用options API的插件。

我定义了一个使用函数清理输入的类，但当我提交选项表单时，它会显示两次错误和信息。

而且我没有成功地显示错误消息。

在验证选项表单时，显示成功和错误消息的正确方式是什么？

非常感谢。

register_setting(
    $this->plugin_slug, // option_group
    $this->plugin_slug, // option_name, for name property of tags
    [$this, \'process_inputs\'] // sanitize_callback
);

public function process_inputs( $input ){
    // sanitize functions:
    // sanitize_email(), sanitize_file_name(), sanitize_html_class(), sanitize_key(), sanitize_meta(), sanitize_mime_type(),
    // sanitize_option(), sanitize_sql_orderby(), sanitize_text_field(), sanitize_textarea_field(), sanitize_title(),
    // sanitize_title_for_query(), sanitize_title_with_dashes(), sanitize_user()
    $options = [];
    if( isset( $input[\'frontend-font\'] ) and $input[\'frontend-font\'] == true ) {
        $options[\'frontend-font\'] = true;
    }else{
        $options[\'frontend-font\'] = false;
    }
    if( isset( $input[\'backend-font\'] ) and $input[\'backend-font\'] == true ){
        $options[\'backend-font\'] = true;
    }else{
        $options[\'backend-font\'] = false;
    }

    // add error/update messages
    // check if the user have submitted the settings
    // wordpress will add the "settings-updated" $_GET parameter to the url
    if ( isset( $_GET[\'settings-updated\'] ) ) {
        // add settings saved message with the class of "updated"*/
        add_settings_error(
            \'persianfont_messages\', // Slug title of setting
            \'wporg_message\', // Slug-name , Used as part of \'id\' attribute in HTML output.
            __( \'settings saved.\', \'persianfont\' ), // message text, will be shown inside styled <div> and <p> tags
            \'error\' // Message type, controls HTML class. Accepts \'error\' or \'updated\'.
        );
    }

    return $options;
}

/**
 * Settings page display callback.
 */
function settings_page_content() {
    // check user capabilities
    if ( ! current_user_can( \'manage_options\' ) ) { return; }

    //var_dump( wp_load_alloptions() ); // print all options

    // show error/update messages
    settings_errors( \'persianfont_messages\' );
    ?>
    <div class="wrap">
        <h1 class="wp-heading-inline"><?php echo esc_html($this->page_title); ?></h1>
        <form method="post" action="options.php">
        <?php
            submit_button();
            settings_fields( $this->plugin_slug ); // This prints out all hidden setting fields
            do_settings_sections( $this->plugin_slug );
            submit_button();
        ?>
        </form>
    </div>
    <?php
}