get_edit_post_link() not working as expected when passed id in plugin

Question

So inside my plugin I have the following code. It gets a question from a custom_post. I'm processing it here so that further updates can be done by AJAX/JSON and the page only has to be configured for one type of data source.

$observations = new WP_Query($args);  
if ( $observations-> have_posts() ) :
    $questionpost = $observations->posts[0];
    $question = array (
        'id' => $questionpost->ID,
        'title' => $questionpost->post_title,
        'name' =>  $questionpost->post_name,
        'excerpt' => $questionpost->post_excerpt,
        'content' => $questionpost->post_content,
        'code' => get_post_meta( $questionpost->ID, 'code', true ),
        'edit_link' => get_edit_post_link($questionpost->ID),
    );
    if ( has_post_thumbnail($questionpost->ID) ) {
        $question['thumbnail'] = get_the_post_thumbnail( $questionpost->ID, 'full', array('class' => 'card-img-top')); 
    } else {
        $question['thumbnail'] = get_template_directory_uri()."/img/no-image.png";
    }
    print_r($question);
}

It all works fine except for the get_edit_post_link - here is print_r dump:

Array ( [id] => 208 [title] => Main ... pipework. [name] => nr-60 [excerpt] => [content] => The ... external. [code] => NR [edit_link] => [thumbnail] => http://.../img/no-image.png ) 

https://codex.wordpress.org/Function_Reference/edit_post_link suggests we can pass an ID so I don't see why this is blank.

Answer 1

According to the get_edit_post_link() function source this can happen in following conditions:

• there is no such post;
• there is no such post type;
• you don't have enough permissions to edit the post;
• _edit_link was changed during post type registration.

The first two are not the case since the ID is available. The fourth is a bad practice: not for general use — core developers recommend you don't use this when registering your own post type.

In this case, the user doesn't have enough permissions. According to the OP's comment under the question, he had been logged out, which is the same sort of thing.

Answer 2

This might be one of those times when certain functions work better as part of the loop. Although you're using a loop, you're not actually using the full WP loop functionality.

Try adding 'posts_per_page'=> 1 to your $args to get just the one post, and then replacing $questionpost = $observations->posts[0]; with the missing loop construct, ie: while($observations->have_posts()) : $observations->the_post(); (not forgetting the closing endwhile; of course). This will then allow you to use the normal in-loop functions (eg, get_the_ID(), get_the_title(), etc) and try using get_edit_post_link() without passing the ID to it.