首先，您应该始终使用WordPress AJAX方法，而不是用于此的自定义函数。看见AJAX in Plugins 在法典中。

考虑到这种做法，您可以这样设置您的请求。将AJAX URL更改为

<?php echo admin_url(\'admin-ajax.php\'); ?> 

并添加\'action\': 输入特定WordPress函数名的值，当服务器端接收到您的数据时，您希望在下一步中执行该函数名。

$(".post_thumbnail").click(function () {
    var id_post = $(this).attr(\'post_id\');
    $.ajax({
        type: \'POST\',
        url: \'<?php echo admin_url(\'admin-ajax.php\'); ?>\',
        data: {
            \'post_id\': id_post,
            \'action\': \'f711_get_post_content\' //this is the name of the AJAX method called in WordPress
        }, success: function (result) {

           alert(result);
        },
        error: function () {
            alert("error");
        }
    });

});

现在我们需要告诉WordPress当有人打电话时该怎么办f711_get_post_content.

在WordPress AJAX中注册操作。这是在Pluginfunctions中完成的。第一部分（“wp\\u ajax\\u”）是告诉WordPress这是一个ajax操作，然后是操作的名称（“f711\\u get\\u post\\u content”）。第二个参数是调用此操作时WordPress执行的函数。

add_action( \'wp_ajax_f711_get_post_content\', \'f711_get_post_content_callback\' );
// If you want not logged in users to be allowed to use this function as well, register it again with this function:
add_action( \'wp_ajax_nopriv_f711_get_post_content\', \'f711_get_post_content_callback\' );

然后创建回调函数。Remember to ALWAYS die() your AJAX functions. 如果您的函数输出JSON，我建议您使用wp_send_json( $array );, 已内置die().

function f711_get_post_content_callback() {

    // retrieve post_id, and sanitize it to enhance security
    $post_id = intval($_POST[\'post_id\'] );

    // Check if the input was a valid integer
    if ( $post_id == 0 ) {
        echo "Invalid Input";
        die();
    }

    // get the post
    $thispost = get_post( $post_id );

    // check if post exists
    if ( !is_object( $thispost ) ) {
        echo \'There is no post with the ID \' . $post_id;
        die();
    }

    echo $thispost->post_content; //Maybe you want to echo wpautop( $thispost->post_content );

    die();

}

这将是推荐的JSON版本。它允许您将多个变量传递回客户端。

function f711_get_post_content_callback() {

    // retrieve post_id, and sanitize it to enhance security
    $post_id = intval($_POST[\'post_id\'] );

    // Check if the input was a valid integer
    if ( $post_id == 0 ) {

        $response[\'error\'] = \'true\';
        $response[\'result\'] = \'Invalid Input\';

    } else {

        // get the post
        $thispost = get_post( $post_id );

        // check if post exists
        if ( !is_object( $thispost ) ) {

            $response[\'error\'] = \'true\';
            $response[\'result\'] =  \'There is no post with the ID \' . $post_id;

        } else {

            $response[\'error\'] = \'false\';
            $response[\'result\'] = wpautop( $thispost->post_content );

        }

    }

    wp_send_json( $response );

}