我有代码可以在我的主题中动态添加一个输入字段。我已经测试了它，作为一个代谢箱，它是有效的。但是，不是在小部件中。

首先添加和更新，代码可以工作，但当我刷新页面或尝试添加更多字段并再次更新时，最旧的字段将被替换为新字段，我的代码有什么问题？

    <?php
/**
 * Adds TMD_Radio_Player.
 */
class TMD_Radio_Player extends WP_Widget {

    /**
     * Register widget with WordPress.
     */
    function __construct() {
        parent::__construct(
            \'tmd_radio_player\', // Base ID
            __(\'TMD Radio Player\', \'text_domain\'), // Name
            array( \'description\' => __( \'Menampilkan radio player\', \'text_domain\' ), ) // Args
        );
    }

    /**
     * Front-end display of widget.
     *
     * @see WP_Widget::widget()
     *
     * @param array $args     Widget arguments.
     * @param array $instance Saved values from database.
     */
    public function widget( $args, $instance ) {

        $title = apply_filters( \'widget-title\', $instance[\'title\'] );

        echo $args[\'before_widget\'];

        if ( ! empty( $title ) )
            echo $args[\'before_title\'] . $title . $args[\'after_title\'];

        $stream_sources = isset( $instance[\'stream_sources\'] ) ? $instance[\'stream_sources\'] : array();

        // Your code here

        echo $args[\'after_widget\'];
    }

    /**
     * Back-end widget form.
     *
     * @see WP_Widget::form()
     *
     * @param array $instance Previously saved values from database.
     */
    public function form( $instance ) {
        if ( isset( $instance[ \'title\' ] ) ) {
            $title = $instance[ \'title\' ];
        }
        else {
            $title = __( \'Radio Player\', \'text_domain\' );
        };

        ?>

        <p>
            <label for="<?php echo $this->get_field_id( \'title\' ); ?>"><?php _e( \'Judul:\' ); ?></label> 
            <input class="widefat" id="<?php echo $this->get_field_id( \'title\' ); ?>" name="<?php echo $this->get_field_name( \'title\' ); ?>" type="text" value="<?php echo esc_attr( $title ); ?>">
        </p>

        <?php 
        $stream_sources = isset( $instance[\'stream_sources\'] ) ? $instance[\'stream_sources\'] : array();
        $counter = 0; 
        if ( is_array( $stream_sources ) ) { ?>
            <?php foreach ( $stream_sources as $source ) {
                if ( isset( $source[\'title\'] ) ) { ?>
                <p> 
                    <?php echo $counter; ?>
                    <!-- title -->
                    <input class="widefat" type="text" id="<?php echo $this->get_field_id(\'stream_sources\'); ?>[$counter][title]" name="<?php echo $this->get_field_name(\'stream_sources\');?>[$counter][title]" value="<?php echo esc_attr( $source[\'title\'] ); ?>">

                    <!-- url -->
                    <input class="widefat" type="text" id="<?php echo $this->get_field_id(\'stream_sources\'); ?>[$counter][url]" name="<?php echo $this->get_field_name(\'stream_sources\');?>[$counter][url]" value="<?php echo esc_attr( $source[\'url\'] ); ?>">

                    <span class="remove-field button button-primary button-large"><?php _e( \'Hapus\', \'textdomain\' ); ?></span>
                </p>
                <?php }
                $counter += 1;
            }
        } ?>

        <span id="<?php echo $this->get_field_id( \'field_clone\' );?>">

        </span>

        <p>
        <span class="<?php echo $this->get_field_id( \'add_field\' );?> button button-primary button-large"><?php _e(\'Tambah Audio\'); ?></span>
        </p>

        <script type="text/javascript">
        var fieldname = <?php echo json_encode($this->get_field_name( \'stream_sources\' )) ?>;
        var fieldid = <?php echo json_encode($this->get_field_id( \'stream_sources\' )) ?>;
        var fieldnum = <?php echo json_encode($counter - 1) ?>; 

        var $ =jQuery.noConflict();
            $(document).ready(function() {
                var count = fieldnum;
                $(\'.<?php echo $this->get_field_id( \'add_field\' );?>\').click(function() {

                    $(\'#<?php echo $this->get_field_id( \'field_clone\' );?>\').append(\'<p>\'+(count+1)+\'<input class="widefat" type="text" id="\'+fieldid+\'[\'+(count+1)+\'][title]" name="\'+fieldname+\'[\'+(count+1)+\'][title]" value=""><input class="widefat" type="text" id="\'+fieldid+\'[\'+(count+1)+\'][url]" name="\'+fieldname+\'[\'+(count+1)+\'][url]" value=""><span class="remove-field button button-primary button-large">Hapus</span></div><!-- end .row --></p>\');
                    count++;
                    return false;
                });
                $(".remove-field").live(\'click\', function() {
                    $(this).parent().remove();
                });
            });
        </script>
        <?php 
    }

    /**
     * Sanitize widget form values as they are saved.
     *
     * @see WP_Widget::update()
     *
     * @param array $new_instance Values just sent to be saved.
     * @param array $old_instance Previously saved values from database.
     *
     * @return array Updated safe values to be saved.
     */
    public function update( $new_instance, $old_instance ) {
        $instance = $old_instance;

        $instance[\'title\'] = ( ! empty( $new_instance[\'title\'] ) ) ? strip_tags( $new_instance[\'title\'] ) : \'\';

        $instance[\'stream_sources\'] = isset( $new_instance[\'stream_sources\'] ) ? $new_instance[\'stream_sources\'] : array();

        return $instance;
    }

} // class TMD_Radio_Player

// register TMD_Radio_Player widget
function register_tmd_radio_player() {
    register_widget( \'TMD_Radio_Player\' );
}
add_action( \'widgets_init\', \'register_tmd_radio_player\' );