Is_single() conditional tag returns null in query

Question

Trying to figure out why this won't work for me. I'm simply trying to run a loop of all posts and pages, and tag them as post and page in a array. But the is_single() conditional is not working, all posts show up as pages. And if I remove the is_page() it'll just give me null

$data = array();
$args = array(
    'posts_per_page' => '-1',
    'post_type' => array('post', 'page'),
    'orderby' => 'menu_order',
    'order' => 'ASC',
);

$loop = new WP_Query($args);
if( $loop->have_posts() ):
    while( $loop->have_posts() ): $loop->the_post();
        $id = $loop->post->ID;        

        if(is_single()) {
            $type = 'article';
        } elseif(is_page()) {
            $type = 'page';
        }

        $data[$id] = array(
            'uri' =>  $loop->post->post_name,
            'title' => apply_filters( 'the_title', $loop->post->post_title ),
            'type' => $type,
            'entry' => apply_filters( 'the_content', $loop->post->post_content ),
        );
    endwhile;
endif;
wp_reset_postdata();

Answer 1

is_single() and is_page() refer to the main query and as far as I know are not altered to match the individual posts in a Loop. They refer to the type of page not to the individual posts. Try and you should see what I mean:

$data = array();
$args = array(
    'posts_per_page' => '-1',
    'post_type' => array('post', 'page'),
    'orderby' => 'menu_order',
    'order' => 'ASC',
);

$loop = new WP_Query($args);
if( $loop->have_posts() ):
    while( $loop->have_posts() ): $loop->the_post();
        $id = $post->ID;        
        the_title(); var_dump($post->post_type,is_single(),is_page(),$loop->is_single(),$loop->is_page());
        echo '<br>';
    endwhile;
endif;
wp_reset_postdata();

The simple solution is just to check the post type itself

if('post' == $post->post_type) {
    $type = 'article';
} elseif('page' == $post->post_type) {
    $type = 'page';
}

Also this,

$id = $loop->post->ID;   

is overly complicated. $post->ID is the same value. Or use get_theID()

Answer 2

is_single() and is_page() operate on the global $wp_query, and won't work in this context. If you're trying to determine post type, check the value of $post->post_type

if( 'post' == $post->post_type ) {
    $type = 'article';
} elseif( 'page' == $post->post_type ) {
    $type = 'page';
}

Answer 3

You could force is_single when replacing the main query:

$draft_post_query = new WP_query(array(
    'post_status' => 'draft',
    'post_type' => array('post'),
    'post__in' => array($post_id)
));
$draft_post = $draft_post_query->post;

global $wp_query, $post;
$wp_query = $draft_post_query;
$post = $draft_post;
$wp_query->is_single = true;
$wp_query->is_singular = true;