3

I'm taking multiple location values with each post, so it's an array (always). My post meta form field is like so:

<select name="<?php echo $project_prefix; ?>offer_locations[]" id="<?php echo $project_prefix; ?>offer_locations" required multiple="multiple">
    ...
    ...
    ...
</select>

If the post already exists without any value for locations, the existing value will come null, but as the field is mandatory, the new location value [on saving] will surely be an array, and we should add the postmeta value.

The conditionals I made with array_diff() is working fine. I made a custom scenario and checked the code, and even in WordPress, I've checked the code (custom code block), as you can see couple of var_dump(), echo and exit() inline. But...

<?php
function save_post_specifics_meta( $post_id ) {
    global $project_prefix;

    // verify nonce
    if (!isset($_POST['post_specifics_nonce']) || !wp_verify_nonce($_POST['post_specifics_nonce'], basename(__FILE__)))
       return $post_id;

    // check autosave
    if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE )
       return $post_id;

    // check permissions
    if ( 'post' == $_POST['post_type'] && !current_user_can('edit_post', $post_id) )
    return $post_id;

    //Location meta data
    $existing_locations = get_post_custom_values( "{$project_prefix}post_locations", $post_id );
    $new_locations      = $_POST["{$project_prefix}post_locations"]; //always an array

    var_dump($existing_locations);  //for debugging only
    var_dump($new_locations);       //for debugging only

    if( is_array( $existing_locations ) ) {
        $new_diff       = array_diff( $new_locations, $existing_locations );
        $existing_diff  = array_diff( $existing_locations, $new_locations );
    } else {
        $new_diff       = $new_locations;
        $existing_diff  = $existing_locations;
    }
    var_dump($new_diff);            //for debugging only
    var_dump($existing_diff);       //for debugging only

    if( $new_diff ) {
        foreach( $new_diff as $new_location ) {
            add_post_meta( $post_id, "{$project_prefix}post_locations", $new_location );
            echo "New Multiple: ", $new_location, '<br>'; //for debugging only
        }
    }

    if( $existing_locations && $existing_diff ) {
        if( is_array( $existing_diff ) ) {
            foreach ( $existing_diff as $existing_location ) {
                delete_post_meta( $post_id, "{$project_prefix}post_locations", $existing_location );
                echo "Delete Multiple: ", $existing_location, '<br>'; //for debugging only
            }
        } else {
            delete_post_meta( $post_id, "{$project_prefix}post_locations", $existing_diff );
            echo "Delete Single: ", $existing_diff, '<br>'; //for debugging only
        }
    }

    exit(); //for debugging only

}

add_action( 'save_post',        'save_post_specifics_meta', 10 );
add_action( 'new_to_publish',   'save_post_specifics_meta', 10 );

On saving or updating post, location meta field is doing as expected. But if the data entry operator hit the Preview Changes button, the add_post_meta() is triggering, even within the true conditional braces, and adding duplicate entries, I don't know how!!! :o

I then added true to the last parameter (line#40) to make the value unique, so that I can stop duplicate entries. But adding true stopped adding any new value to the meta_key even on saving.

How can I stop adding meta value on Preview Changes hit?

  • 2
    Maybe you could check for the $_POST variable submitted, when triggering »Preview Changes«, to not save on on preview. It should be $_POST[ 'wp-preview' ] = 'dopreview' - just an idea though, no certainty if this will actually suffice. – Nicolai Oct 25 '15 at 18:32
  • @ialocin Thanks for pointing there. I don't wanna bypass just now, I need to figure out what's happening there... I var_dump($post_id); exit();, and hitting Preview Changes reveal that the $post_id is not passing exact when hitting preview changes, because it's creating an inherit post_status (a revision) with a different post_id (#1407) of actual post_id (#1301). That's why, get_post_custom_values( "{$project_prefix}post_locations", $post_id ); is missing values completely on "Preview" hit. How can I let the system get the actual post_id when in revision mode? – Mayeenul Islam Oct 27 '15 at 5:48
  • 2
    The post_parent column of a revision contains the $post_id of the post of which the revision is a version from. So something like $rev_obj = get_post( 1407 ); $parent_post_id = $rev_obj->post_parent; should work. – Nicolai Oct 27 '15 at 11:04
  • 2
    @ialocin it's completely ok. Everybody is busy. I's just concern that, after all, I got the solution based on your comments. So the credit goes to you. <3 – Mayeenul Islam Oct 27 '15 at 18:04
  • 1
    no worries, let me say it with Linus Torvalds, I'm doing this just for fun - and not for points - so all is good :) – Nicolai Oct 27 '15 at 21:33
2

Actually I'd love to have an answer from @ialocin, because he suggested me the way. But as the code is a bit long for comment field I'm posting it here as an answer. But I'd love to accept an answer more appropriate to the situation:

After @ialocin's suggestion, I got that, the $post_id wasn't accurate for a Preview Changes hit, so the $existing_locations wasn't getting the correct db info. Now I changed the following line:

$existing_locations = get_post_custom_values( "{$project_prefix}post_locations", $post_id );

into the following conditional lines:

if( $_POST[ 'wp-preview' ] === 'dopreview' ) {
    //if it's a preview hit, grab the actual post's data
    $actual_post_id     = wp_get_post_parent_id( $post_id );
    $existing_locations = get_post_custom_values( "{$project_prefix}post_locations", $actual_post_id );
} else {
    //else, go with the actual post
    $existing_locations = get_post_custom_values( "{$project_prefix}post_locations", $post_id );
}

Everything is working as expected in localhost. Though sometimes, the Preview hit fails the preview_id and preview_nonce etc. and doesn't show the preview, but when they're set, the preview is, exactly what it should be.

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