Formatting custom meta box date from YYYY/MM/DD to a more readable alternative

Question

QUESTION

This is following a previous question that was graciously answered by Milo earlier here - How to sort CPT by custom meta value (date), and return posts month by month

In short, I'm having some issues with properly formatting my custom meta box date's in a few areas... Namely, in the back-end in my custom columns, and then in the front-end in my archive template.

For example, in my archive template I'm trying to return the current date that the posts belong to via the code pasted below, but when I visit a month with no posts my template returns the date "January 1970" instead.

<?php $calendar_month = get_post_meta($post->ID, 'epr_startdate', TRUE);?>
<?php $this_month = strtotime($calendar_month); ?>
<span id="current_month"><?php echo date( 'F Y', $this_month ); ?></span>
                

Additionally, in the back-end I'm trying to have it so that if just the "start date" is created then ONLY output that information, whereas, if the user enters both a "start date" and an "end date" then retun both dates, but when I use the code example below my start dates are returned in duplicate like this instead: Mar 3, 2013 — Mar 3, 2013.

case "eventdate":
                $eventstart = get_post_meta($post->ID, 'epr_startdate', true);
                $eventstart_col = strtotime($eventstart);

                $eventend = get_post_meta($post->ID, 'epr_enddate', true);
                $eventend_col = strtotime($eventend);

                if ( get_post_meta($post->ID, 'epr_startdate', true) && ! get_post_meta($post->ID, 'epr_enddate', true) )
                    echo date( 'M n, Y', $eventstart_col );
                elseif ( get_post_meta($post->ID, 'epr_enddate', true) )
                    echo date( 'M n, Y', $eventstart_col ) . ' — ' . date( 'M n, Y', $eventend_col );
                else
                    echo 'NA';
                break;

Thank you in advance for your time.
Best

---

FINAL SOLUTION

Big thank you to s_ha_dum for his patience and support!
Pasted below are the final working solutions to my question...

Correctly outputting the date when no posts exist for the currently queried month:

<?php $this_month = strtotime($calendar_month);
if (false === $this_month) {
$this_month = strtotime(get_query_var( 'calendar_year' ) . get_query_var( 'calendar_month' ) .'01');
} ?>
<span id="current_month"><?php echo date( 'F Y', $this_month ); ?></span><?php
?>

Custom columns:

case "eventdate":
                $start_date = get_post_meta($post->ID, 'epr_startdate', true);
                $start_date_col = strtotime($start_date);           
                $end_date = get_post_meta($post->ID, 'epr_enddate', true);
                $end_date_col = strtotime($end_date);
                
                if ( $start_date_col && !$end_date_col ) 
                    echo date( 'M d, Y', $start_date_col );
                elseif ( $start_date_col && $end_date_col )
                    echo date( 'M d, Y', $start_date_col ) . ' — ' . date( 'M d, Y', $end_date_col );  
                else
                    echo 'NA';
                break;

Redirecting /calendar -> /calendar/yyyy/mm:

function redirect_empty_archive() {
$m = get_query_var('calendar_month');
$y = get_query_var('calendar_year');
    if (
        is_post_type_archive('calendar') &&
        ( empty($m) || empty($y) )
    ) {
        wp_safe_redirect( '/calendar' . date('/Y/m') );
    }
}
add_action('template_redirect','redirect_empty_archive');

Answer 1

but when I visit a month with no posts my template returns the date "January 1970" instead.

Yes. That will happen. UNIXTIME began on Jan 1, 1970. That is "0000/00/00" but negative numbers work back until sometime in 1901. strtotime will return false for anything outside that range, including your nonexistent dates. date will assume "day zero" if given a bad date, hence you get Jan 1, 1970 for nonexistent or otherwise flawed dates. 64 bit machines can handle larger ranges, if I remember correctly. Either way a nonexistent date will give you 1970. Try:

$calendar_month = "1901/01/01";
$this_month = strtotime($calendar_month);
var_dump($this_month);
echo '<br />';
echo date('Y',$this_month);
echo '<br />';

You want to make sure you have a good date before displaying it.

<?php $this_month = strtotime($calendar_month); 
if (false !== $this_month) { ?>
  <span id="current_month"><?php echo date( 'F Y', $this_month ); ?></span><?php
}

Your other code is a little bulky, but looks like it should work except that your date format is wrong. You aren't getting "Month Day, Year" as I suspect you want but "Month-Name Month-Number, Year", which will look like a duplicate if the two dates are in the same month/year. Take a good look at the date formatting operators.

$eventstart = get_post_meta($post->ID, 'epr_startdate', true);
$eventstart_col = strtotime($eventstart);

$eventend = get_post_meta($post->ID, 'epr_enddate', true);
$eventend_col = strtotime($eventend);

if ( $eventstart_col && !$eventend_col ) {
    // only the start date
    echo date( 'M d, Y', $eventstart_col );
} elseif ( $eventstart_col && $eventend_col ) {
    // both start and end date
    echo date( 'M d, Y', $eventstart_col ) . ' — ' . date( 'M d, Y', $eventend_col );  
} else {
    echo 'NA';
}

I think I have that put back together correctly.