我目前正在制作一个可湿性粉剂小部件，我一直坚持这样做。

我想传递一个变量$emailReceiver 从我的form() 方法到我的deliver_mail() 方法问题是我的deliver_mail() 方法已首先执行，它给出以下错误：

“未捕获的phpmailerException：无效地址：…PHPMailer->addaddaddress（NULL）”

这个想法是，当表单显示在小部件部分时，用户应该填写收件人的电子邮件地址。

 add_action( \'widgets_init\', \'contact_form_register_widget\' );
 $add_action = new jpen_Custom_Form_Widget();
 $add_action->init();

function contact_form_register_widget() {
    register_widget( \'jpen_Custom_Form_Widget\');

    wp_register_script( "contact-form-script-widget", WP_PLUGIN_URL.\'/contact-form-widget/contact-form-script-widget.js\', array(\'jquery\') );
    wp_localize_script( \'contact-form-script-widget\', \'contactFormAjax\', array( \'ajaxurl\' => admin_url( \'admin-ajax.php\' )));

    wp_enqueue_script( \'jquery\' );
    wp_enqueue_script( \'contact-form-script-widget\' );
}

class jpen_Custom_Form_Widget extends WP_Widget {
    //private $emailReceiver;

    public function __construct() {
        $widget_options = array(
            \'classname\' => \'custom_form_widget\',
            \'description\' => \'This is a Custom Form Widget\',
        );

        parent::__construct( \'custom_form_widget\', \'Custom Form Widget\', $widget_options );
         );

    } 

    //Hooks in a separate class method
    public function init() {

        add_action( \'wp_ajax_send_mail\', array( $this, \'deliver_mail\' ) );
        add_action( \'wp_ajax_nopriv_send_mail\', array( $this, \'deliver_mail\' ) );
    }

    //deliver mail    
    function deliver_mail() {     

        //name of button 
        require_once "C:/xampp/htdocs/WP/wp-includes/class-phpmailer.php";

        // sanitize form values
        $name    = sanitize_text_field( $_POST["name"] );
        $email   = sanitize_email( $_POST["email"] );
        $subject = sanitize_text_field( $_POST["subject"] );
        $message = esc_textarea( $_POST["message"] );
        // get the blog administrator\'s email address

        $headers = "From: $name <$email>" . "\\r\\n";

        // Localhost
        $mail = new PHPMailer(true);
        $mail->IsSMTP(); // telling the class to use SMTP
        $mail->CharSet = \'UTF-8\';

        $mail->SMTPDebug = 0;                     // enables SMTP debug information (for testing)
        $mail->SMTPAuth = true;                  // enable SMTP authentication
        $mail->SMTPSecure = "ssl";                 // sets the prefix to the servier
        $mail->Host = "mail.gmx.com";      // sets GMX as the SMTP server for example: mail.gmx.com
        $mail->Port = 465;                 // set the SMTP port for the GMX server


        $mail->Username = $email;
        $mail->Password = \'PASS\';

        $mail->SetFrom($email, $name);
        $mail->AddAddress($instance[\'email\']);
         //Here has to be accessed $instance[\'email\'] variable from the form() function;

        $mail->Subject = $subject;
        $mail->MsgHTML($message);

        $headers .= "Content-Type: text/html; charset=utf-8";
        $headers .= "Content-Transfer-Encoding: 8bit";

        try {
            $mail->send();
            $msg = "An email has been sent for verfication.";
            $msgType = "success";

            // wp_safe_redirect( home_url(), 302 );
            //exit();

        } catch (Exception $ex) {
            $msg = $ex->getMessage();
            $msgType = "warning";

            //wp_safe_redirect( home_url(), 302 );
            //exit();
        }

        die();
    }    

    function widget( $args, $instance ) {

        echo $args[\'before_widget\'];


        ?>
<form action="<?php esc_url( $_SERVER[\'REQUEST_URI\'] )?>" method="post" class="contact-form" id="contact-form" >
    <div class=header-contact>
        <p><h2>Contact Form</h2></p>
        <hr>
    </div>
    <div class=input-containers>
        <input type="text" id="name" name="cf-name" pattern="[a-zA-Z0-9 ]+" value="" size="40" placeholder="Име и фамилия"/>
    </div>
    <div class=input-containers>
        <input type="email" id="email" name="cf-email" value="" size="40" placeholder="Поща"/>
    </div>
    <div class=input-containers>
        <input type="text" id="subject" name="cf-subject" pattern="[a-zA-Z ]+" value="" size="40" placeholder="Относно"/>
    </div>
    <div class=input-containers>
        <textarea rows="10" id="message" cols="35" name="cf-message" placeholder="Текст"></textarea>
    </div>
    <div class=input-containers>
        <input type="submit" name="cf-submitted" value="Send" id="submitForm">
        <input type="hidden" name="form_submitted" id="ajax_url" value="<?php echo admin_url(\'admin-ajax.php\'); ?>" />
    </div>
    <button id="btn1">Bacon Button1</button>
    <p id="verify" style="display:none;">Your message has been sent.<br /><br /></p> 
</form>
<script>

</script>
<?php
       echo $args[\'after_widget\']; 
    }

    public function update( $new_instance, $old_instance ) {    
        var_dump( $new_instance);
        return $new_instance;  
    }

    // Displays form in the widget section which the user should use to fill the receiver\'s email address.
    public function form( $instance )
    {

        $emailReceiver = \'\';
        if( !empty( $instance[\'email\'] ) ) {
            $emailReceiver = $instance[\'email\'];
        }

        ?>    
    <p>
        <label for="<?php echo $this->get_field_name( \'email\' ); ?>"><?php _e( \'Email:\' ); ?></label>
        <input class="widefat" id="<?php echo $this->get_field_id( \'email\' ); ?>" name="<?php echo $this->get_field_name( \'email\' ); ?>" type="text" value="<?php echo esc_attr( $emailReceiver ); ?>" />
    </p>
    <?php 
    if(!isset($emailReceiver) || trim($emailReceiver) == \'\') {
        echo "You did not fill out title field.";
    }
    ?>
<?php
    }
}