我正在WordPress中创建一个自定义表单来存储数据并将其发送到外部数据库。作为测试的一部分，我成功地创建了一个表单，通过单击submit按钮将表单引用回自身，将表单数据提交到外部数据库。

我现在想利用WordPress管理帖子功能，而不是让表单引用回自身。我已经正确设置了操作挂钩，因为在提交表单后，我会使用以下方式显示$\\u POST变量：

<form action="<?php echo esc_url( admin_url( \'admin-post.php\' ) ); ?>" method="post" id="test" >

我的问题是，外部数据库是否可以用于管理帖子？此时，当为外部数据库连接引用全局变量时，会抛出一个PHP错误，说明insert引用的是空值。以下是与此问题相关的代码。。。

<?php
class x94 {

    public function __construct(){
        add_action( \'admin_post_submitForm9\', array( $this, \'formHandling\' ), 11, 1 );
        add_action( \'wp_head\', array( $this, \'externalDB\' ), 10, 1 );
    }

    //External DB connection
    function externalDB(){ 
        global $externalDB;
        $externalDB = new wpdb(DB_USER2, DB_PASSWORD2, DB_NAME3, DB_HOST2);
    }

    //create form
    function userForm() {
    //Global Variables

        global $externalDB;
        //print_r($externalDB);

        // starts output buffering
        ob_start(); 
        ?>
        <form action="<?php echo esc_url( admin_url( \'admin-post.php\' ) ); ?>" method="post" id="test" >

            <input type="hidden" name="action" id="userForm_action" value="submitForm9" />
            <input type="text" name="visitor_name" id="visitor_name" /> 
            <input type="text" name="visitor_age" id="visitor_age" /> 
            <input type="text" name="visitor_gender" id="visitor_gender" /> 

            <input type="submit" name="submit_form" value="submit" />

        </form>
        <?php
        $html = ob_get_clean();

        if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] != "" ) {
            //$_POST Variables
            $name = strip_tags($_POST["visitor_name"], "");
            $age = $_POST[\'visitor_age\'];  
            $gender = $_POST[\'visitor_gender\']; 



        }
        // if the form is submitted but the name is empty
        if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] == "" )
            $html .= "<p>You need to fill the required fields.</p>";
        // outputs everything
        return $html;

    }

    function formHandling(){

        global $externalDB;
        print_r($externalDB); //not displaying data, global not recognized
        print_r($_POST); //displays data

        if (1 == 1){

            $externalDB->insert( 
                \'basic_user_info\', 
                array( 
                    \'name\' => $name, 
                    \'age\'  => $age,
                    \'gender\'=> $gender,

                ),
                //field formats
                array(\'%s\',
                      \'%s\',
                      \'%s\',
                      )
            );
            //$html = "<p>Your name <strong>$name</strong> was successfully recorded. Thanks!!</p>";
            die();
        }
    }
}//end class

//shortcodes
add_shortcode(\'basic-info\', array( \'x94\', \'userForm\' ) );


new x94();
?>

<?php
class x94 {

    private $externalDB01;

    public function __construct(){
        add_action( \'admin_post_submitForm9\', array( $this, \'formHandling\' ), 11, 1 );
        add_action( \'plugins_loaded\', array( $this, \'externalDB\' ), 10, 1 );
    }

    //External DB connection
    function externalDB(){ 
        $this->externalDB01 = new wpdb(DB_USER2, DB_PASSWORD2, DB_NAME3, DB_HOST2);
    }

    //create form
    function userForm() {

        ob_start(); 
        ?>
        <form action="<?php echo esc_url( admin_url( \'admin-post.php\' ) ); ?>" method="post" id="test" >

            <input type="hidden" name="action" id="userForm_action" value="submitForm9" />
            <input type="text" name="visitor_name" id="visitor_name" /> 
            <input type="text" name="visitor_age" id="visitor_age" /> 
            <input type="text" name="visitor_gender" id="visitor_gender" /> 

            <input type="submit" name="submit_form" value="submit" />

        </form>
        <?php
        $html = ob_get_clean();
        return $html;

    }

    function formHandling(){

        if ( isset( $_POST) ) { 

            //sanatize data from the admin-post array
            $name   = sanitize_text_field( $_POST[\'vistor_name\'] );
            $age    = sanitize_text_field( $_POST[\'vistor_age\'] );
            $gender = sanitize_text_field( $_POST[\'vistor_gender\'] );

            //submit data to external database
            $externalDB->insert( 
                \'basic_user_info\', 
                array( 
                    \'name\' => $name, 
                    \'age\'  => $age,
                    \'gender\'=> $gender,

                ),
                //field formats
                array(\'%s\',
                      \'%s\',
                      \'%s\',
                      )
            );
        }
        else {

            wp_die();
        }
    }
}//end class

//shortcodes
add_shortcode(\'basic-info\', array( \'x94\', \'userForm\' ) );


new x94();
?>