Using WP_Query() to check if a post exists by slug - wordpress

Question

I am writing a 404.php for wordpress. I have the plugin 'rolescoper' installed, and some pages require the user be logged in to view. Rolescoper doesn't offer any way to distinguish between a page not found (404) and a permission denied (403).
I've been able to build this functionality into my pages using the following code:
$the_query = new WP_Query ( 'pagename=' . $_SERVER['REQUEST_URI'] );
$is_valid_page = ! empty ( $the_query -> queried_object -> post_title );
But, surprisingly, the same method does does not work for posts:
$args = array (
'post_type' => 'post',
'name' => str_replace ( "/", "", $_SERVER['REQUEST_URI'] )
);
$the_post_query = new WP_Query ( $args );
$is_valid_post = ! empty ( $the_post_query -> queried_object -> post_title );
When I do a var_dump on $the_post_query i get something that shows 0 results found. I am sure that the page I'm checking for exists.
Any idea how to use wp_query() to query for a post by slug?
Thanks!

Answer 1

After digging through the docs, I found that Rolescoper provided a nice function, is_restricted_rs(), for solving this problem:
//get the slug requested
$slug = $_SERVER [ 'REQUEST_URI' ];
//First check if it's a page and restricted
$page_id = get_page_by_path ( $slug )->ID;
$page_restricted = is_restricted_rs ( $page_id );
//Then check if it's a post and restricted
$args = array(
'name' => $slug,
'post_type' => 'post',
'post_status' => 'publish',
'numberposts' => 1
);
$my_posts = get_posts($args);
if ( $my_posts ) {
$post_id = $my_posts[0]->ID;
}
$post_restricted = is_restricted_rs ( $post_id );
//then set $content_restricted for use below
$content_restricted = $post_restricted || $page_restricted;

Answer 2

The rolescoper plugin has become defunct and we developed a solution which does not require any external plugin. Instead, we added some code to our theme and added a custom field to each page that we wanted to restrict access to.
This isn't as robust as rolescoper was, but for our use case it was perfect. We have only a few user classes and so I just hardcode the different classes and that's enough for us. I'm sure a similar solution could be used for more complex cases, especially if you expanded on the custom UI code.
I happened to name the field "dhamma_perms" but you could name it anything you want:
function is_restricted() {
return item_restricted(get_post(), wp_get_current_user());
}
function item_restricted($page, $user) {
$dhamma_perms = get_post_meta($page->ID, "dhamma_perms", true);
$requires_os = $dhamma_perms == "oldstudents";
$requires_worker = $dhamma_perms == "workers";
if (!is_user_logged_in()) {
return $requires_os || $requires_worker;
} else if (get_userdata($user->ID)->user_login == "oldstudent") {
return $requires_worker;
} else {
//dhammaworkers and all named users have full read access
return false;
}
}
I then modified any page which could be restricted to have code like this at the top:
<?php get_header(); ?>
<?php if (is_restricted()) : ?>
<?php show_404(); ?> //I just pasted the full content of our 404 page into a function. The 404 page shows a faux-403 page (WP doesn't have real 403 pages) if the content exists but is restricted.
<?php else: ?>
//show normal page stuff
I also modified the header.php to have a proper title for 404 and 403 pages:
<?php if (is_restricted()) : ?>
<title> <?php echo "Login Required " . get_theme_mod('dhamma_title_separator') . " " . get_bloginfo('name'); ?></title>
<?php else: ?>
<title><?php wp_title( get_theme_mod('dhamma_title_separator'), true, "right" ); bloginfo('name'); ?></title>
<? endif; ?>
Finally, I added a custom UI to posts and pages so it's easy to select permissions:
//Register the permissions metabox for posts and pages
function add_perms_box( $post ) {
$screens = [ 'post', 'page', 'wporg_cpt' ];
foreach ( $screens as $screen ) {
add_meta_box(
'dhamma_perms_box', // Unique ID
'Permissions', // Box title
'perms_box_html', // Content callback, must be of type callable
$screens // Post type
);
}
}
function perms_box_html() {
$value = get_post_meta(get_the_ID(), "dhamma_perms", true);
?>
<select name="dhamma_perms" id="dhamma_perms" class="postbox">
<option value="public" <?php selected($value, 'public');?>>Public</option>
<option value="oldstudents" <?php selected($value, 'oldstudents');?>>Old Students Only</option>
<option value="workers" <?php selected($value, 'workers');?>>Dhamma Workers Only</option>
</select>
<?php
}
add_action('add_meta_boxes', 'add_perms_box');
function dhamma_meta_save( $post_id ) {
// Checks save status
$is_autosave = wp_is_post_autosave( $post_id );
$is_revision = wp_is_post_revision( $post_id );
// Exits script depending on save status
if ( $is_autosave || $is_revision ) {
return;
}
// Checks for input and sanitizes/saves if needed
if( isset( $_POST[ 'dhamma_perms' ] ) ) {
update_post_meta( $post_id, 'dhamma_perms', $_POST[ 'dhamma_perms' ] );
}
}
add_action( 'save_post', 'dhamma_meta_save' );
This created a new dropdown on each page and post for us:
I hope this is helpful for anyone else trying to get some simple permissions on a wordpress site!