我有这个小部件代码，它使用登录谷歌按钮来获取用户凭据，并最终获取他们的谷歌评论。按钮工作正常，我能够获得凭据和CSRF令牌。我试图将它们保存在WordPress中供以后使用，但这两个值不会保存，其他值保存。

public function form( $instance ) {
        $title = ! empty( $instance['title'] ) ? $instance['title'] : __( 'Google Maps Reviews', 'text_domain' );
        $place_id = ! empty( $instance['place_id'] ) ? $instance['place_id'] : '';
        $api_key = ! empty( $instance['api_key'] ) ? $instance['api_key'] : '';

        if ( !empty( $_POST['credential'] ) ) {
            $google_credential = $_POST['credential'];
        } else {            
            $google_credential = $instace['google_credential'];
            echo "instance credential: "; 
        }

        if ( !empty( $_POST['g_csrf_token'] ) ) {
            
            $google_csrf_token = $_POST['g_csrf_token'];
        } else {
            $google_csrf_token = $instace['google_csrf_token'];
        }
        
        ?>
        <?php if(empty($_POST['credential'])){ ?>
            <script src="https://accounts.google.com/gsi/client" async defer></script>
        <?php } ?>

        <p>
            <label for="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>"><?php _e( 'Title:' ); ?></label> 
            <input class="widefat" id="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'title' ) ); ?>" type="text" value="<?php echo esc_attr( $title ); ?>">
        </p>
        <p>
            <label for="<?php echo esc_attr( $this->get_field_id( 'place_id' ) ); ?>"><?php _e( 'Place ID:' ); ?></label> 
            <input class="widefat" id="<?php echo esc_attr( $this->get_field_id( 'place_id' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'place_id' ) ); ?>" type="text" value="<?php echo esc_attr( $place_id ); ?>">
        </p>
        <p>
            <label for="<?php echo esc_attr( $this->get_field_id( 'api_key' ) ); ?>"><?php _e( 'API Key:' ); ?></label> 
            <input class="widefat" id="<?php echo esc_attr( $this->get_field_id( 'api_key' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'api_key' ) ); ?>" type="text" value="<?php echo esc_attr( $api_key ); ?>">
        </p>

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

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

        <?php if(empty($_POST['credential'])){ ?>
            <div id="g_id_onload"
                data-client_id="{removed for security}.apps.googleusercontent.com"
                data-context="signin"
                data-ux_mode="popup"
                data-login_uri="https://{removed for security}/wp-admin/widgets.php"
                data-auto_prompt="false">
            </div>

            <div class="g_id_signin"
                data-type="standard"
                data-shape="rectangular"
                data-theme="filled_blue"
                data-text="signin_with"
                data-size="large"
                data-locale="es-419"
                data-logo_alignment="left">
            </div>
        <?php } ?>
        

        

        <?php 
    }

   

    public function update( $new_instance, $old_instance ) {
        $instance = array();
        $instance['title'] = ( ! empty( $new_instance['title'] ) ) ? sanitize_text_field( $new_instance['title'] ) : '';
        $instance['place_id'] = ( ! empty( $new_instance['place_id'] ) ) ? sanitize_text_field( $new_instance['place_id'] ) : '';
        $instance['api_key'] = ( ! empty( $new_instance['api_key'] ) ) ? sanitize_text_field( $new_instance['api_key'] ) : '';
        $instance['google_credential'] = ( ! empty( $new_instance['google_credential'] ) ) ? sanitize_text_field( $new_instance['google_credential'] ) : '';
        $instance['google_csrf_token'] = ( ! empty( $new_instance['google_csrf_token'] ) ) ? sanitize_text_field( $new_instance['google_csrf_token'] ) : '';
        return $instance;
    }