显示文本区域WP中的变量

Question

<?php 
    /*
    ...
    */
    add_action( 'init', 'register_shortcode_mail');

    function register_shortcode_mail(){
       add_shortcode('mail-sender', 'mail_sender_function');
    }

    function mail_sender_function(){

        echo "<form name='myForm' method='POST'>
            Subject: <input type='text' name='subject'>
            <textarea rows = '5' cols = '80' name = 'message' form = 'usrform'>
            </textarea>
            <input type = 'Submit' name='btn' value = 'Send'>
        </form>";
        if(isset($_POST['btn'])){
            $sub = $_POST['subject'];
            $mes = $_POST['message'];
            echo "$mes";
        }

    }
?>

嗨。我试图在wordpress站点上显示textarea($mes)的内容，但是每当我单击Submit btn时，所有的输入框都包含一些文本，清除自身，没有回显。

Answer 1

将isset($_POST['btn'])替换为$_SERVER["REQUEST_METHOD"] == "POST"