Date format with genitive case of the month name is not working

Question

Wordpress 4.4 indroduced a way to display the genitive case of a months name for specific locale by using the function date_i18n (https://core.trac.wordpress.org/ticket/11226#comment:32) which is filtered by wp_maybe_decline_date() (https://core.trac.wordpress.org/browser/tags/4.6/src/wp-includes/functions.php#L172). Even though both my locale (el) and the translation of the string "decline months names: on or off" in my el.po file are correct, the genitive case of the months name is not working. So with this: echo date_i18n( 'j F Y', strtotime( '2016/9/20' ) ); I got the date with the month name in nominative case.

Any ideas? Thanks in advance!

Answer 1

Although, in my wp your echo displayed correctly (so maybe double check that you use the correct locale and that "decline months names: on or off" is translated as "on" in your locale), you can "force" genitive case, by making a generic wrap function based on the wp_maybe_decline_date().

I have tested and used this, in order to overcome the wp_maybe_decline_date() regex that ,matches formats like 'j F Y' or 'j. F', while I wanted to use 'l j F Y'

Example use case:

In our theme functions.php we define the wrapper function like:

/**
 * [multi_force_use_genitive_month_date]
 * Call this to force genitive use case for months in date translation
 * @param  string $date Formatted date string.
 * @return string The date, declined if locale specifies it.
 */
function multi_force_use_genitive_month_date( $date ) {
    global $wp_locale;

    // i18n functions are not available in SHORTINIT mode
    if ( ! function_exists( '_x' ) ) {
        return $date;
    }

    /* translators: If months in your language require a genitive case,
     * translate this to 'on'. Do not translate into your own language.
     */
    if ( 'on' === _x( 'off', 'decline months names: on or off' ) ) {
        // Match a format like 'j F Y' or 'j. F'
        $months          = $wp_locale->month;
        $months_genitive = $wp_locale->month_genitive;

        foreach ( $months as $key => $month ) {
            $months[ $key ] = '# ' . $month . '( |$)#u';
        }

        foreach ( $months_genitive as $key => $month ) {
            $months_genitive[ $key ] = ' ' . $month . '$1';
        }

        $date = preg_replace( $months, $months_genitive, $date );
    }

    // Used for locale-specific rules
    $locale = get_locale();

    return $date;
}

Then, in our template file where we want the genitive case to appear, we wrap the date_i18n(), like:

<?php echo multi_force_use_genitive_month_date( date_i18n( 'l j F Y' ) ); ?>

Hope this helps.

Answer 2

Updated, working version based on the code from @Cubakos:

function multi_force_use_genitive_month_date( $date ) {
   global $wp_locale;

   $months          = $wp_locale->month;
   $months_genitive = $wp_locale->month_genitive;

   $date = str_replace( $months, $months_genitive, $date );

   return $date;
}

Usage in posts loop

<?= multi_force_use_genitive_month_date(get_the_date()); ?>