我试图断言current_user_can() 在permission_callback a的方法register_rest_route 作用但是，它总是返回false。

经过进一步调试，我发现wp_get_current_user() 函数返回ID零，这可能意味着$current_user 全局在执行时不可用。

这意味着this example 从文档中可以看出：

<?php
add_action( \'rest_api_init\', function () {
    register_rest_route( \'myplugin/v1\', \'/author/(?P<id>\\d+)\', array(
        \'methods\' => \'GET\',
        \'callback\' => \'my_awesome_func\',
        \'args\' => array(
            \'id\' => array(
                \'validate_callback\' => \'is_numeric\'
            ),
        ),
        \'permission_callback\' => function () {
            return current_user_can( \'edit_others_posts\' );
        }
    ) );
} );

进一步调试：

<?php
// muplugins/test.php
add_action(\'rest_api_init\', function() {

    // Works. Returns current WP_User.
    wp_get_current_user();

    // Works. Returns current WP_User.
    global $current_user;

    register_rest_route(\'test\', \'user\', [
       \'methods\' => \'GET\',

        // In a closure. Does not work. Returns zero.
       \'callback\' => function() {
           var_dump(wp_get_current_user());exit;
       },

        // In a class. Does not work. Returns zero.
        \'callback\' => [new Something, \'test_wp_get_current_user_in_a_class\'], 

        // In a function. Does not work. Returns zero.
        \'callback\' => \'test_wp_get_current_user\',

        \'permission_callback\' => function() {
            // Does not work. Returns zero.
            wp_get_current_user();

            // Does not work. Returns zero.
            global $current_user;
            $current_user->ID;
        }
    ]);
});

function test_wp_get_current_user()
{
    var_dump(wp_get_current_user());exit;
}

class Something
{
    public function test_wp_get_current_user_in_a_class()
    {
        var_dump(wp_get_current_user());exit;
    }
}