wordpress教程：如何利用get_calendar函数实现统计文章发布日历

如何利用get_calendar函数实现统计文章发布日历，下面web建站小编给大家简单介绍一下具体实现方法。

函数原型：

get_calendar( bool $initial = true, bool $display = true ): void|string

参数说明：

$initial，是否使用初始日历名称。

$display，直接显示，还是返回一个字符串。

函数源码：

function get_calendar( $initial = true, $display = true ) {
  global $wpdb, $m, $monthnum, $year, $wp_locale, $posts;

  $key   = md5( $m . $monthnum . $year );
  $cache = wp_cache_get( 'get_calendar', 'calendar' );

  if ( $cache && is_array( $cache ) && isset( $cache[ $key ] ) ) {
    /** This filter is documented in wp-includes/general-template.php */
    $output = apply_filters( 'get_calendar', $cache[ $key ] );

    if ( $display ) {
      echo $output;
      return;
    }

    return $output;
  }

  if ( ! is_array( $cache ) ) {
    $cache = array();
  }

  // Quick check. If we have no posts at all, abort!
  if ( ! $posts ) {
    $gotsome = $wpdb->get_var( "SELECT 1 as test FROM $wpdb->posts WHERE post_type = 'post' AND post_status = 'publish' LIMIT 1" );
    if ( ! $gotsome ) {
      $cache[ $key ] = '';
      wp_cache_set( 'get_calendar', $cache, 'calendar' );
      return;
    }
  }

  if ( isset( $_GET['w'] ) ) {
    $w = (int) $_GET['w'];
  }
  // week_begins = 0 stands for Sunday.
  $week_begins = (int) get_option( 'start_of_week' );

  // Let's figure out when we are.
  if ( ! empty( $monthnum ) && ! empty( $year ) ) {
    $thismonth = zeroise( (int) $monthnum, 2 );
    $thisyear  = (int) $year;
  } elseif ( ! empty( $w ) ) {
    // We need to get the month from MySQL.
    $thisyear = (int) substr( $m, 0, 4 );
    // It seems MySQL's weeks disagree with PHP's.
    $d         = ( ( $w - 1 ) * 7 ) + 6;
    $thismonth = $wpdb->get_var( "SELECT DATE_FORMAT((DATE_ADD('{$thisyear}0101', INTERVAL $d DAY) ), '%m')" );
  } elseif ( ! empty( $m ) ) {
    $thisyear = (int) substr( $m, 0, 4 );
    if ( strlen( $m ) < 6 ) {
      $thismonth = '01';
    } else {
      $thismonth = zeroise( (int) substr( $m, 4, 2 ), 2 );
    }
  } else {
    $thisyear  = current_time( 'Y' );
    $thismonth = current_time( 'm' );
  }

  $unixmonth = mktime( 0, 0, 0, $thismonth, 1, $thisyear );
  $last_day  = gmdate( 't', $unixmonth );

  // Get the next and previous month and year with at least one post.
  $previous = $wpdb->get_row(
    "SELECT MONTH(post_date) AS month, YEAR(post_date) AS year
    FROM $wpdb->posts
    WHERE post_date < '$thisyear-$thismonth-01'
    AND post_type = 'post' AND post_status = 'publish'
      ORDER BY post_date DESC
      LIMIT 1"
  );
  $next     = $wpdb->get_row(
    "SELECT MONTH(post_date) AS month, YEAR(post_date) AS year
    FROM $wpdb->posts
    WHERE post_date > '$thisyear-$thismonth-{$last_day} 23:59:59'
    AND post_type = 'post' AND post_status = 'publish'
      ORDER BY post_date ASC
      LIMIT 1"
  );

  /* translators: Calendar caption: 1: Month name, 2: 4-digit year. */
  $calendar_caption = _x( '%1$s %2$s', 'calendar caption' );
  $calendar_output  = '<table id="wp-calendar" class="wp-calendar-table">
  <caption>' . sprintf(
    $calendar_caption,
    $wp_locale->get_month( $thismonth ),
    gmdate( 'Y', $unixmonth )
  ) . '</caption>
  <thead>
  <tr>';

  $myweek = array();

  for ( $wdcount = 0; $wdcount <= 6; $wdcount++ ) {
    $myweek[] = $wp_locale->get_weekday( ( $wdcount + $week_begins ) % 7 );
  }

  foreach ( $myweek as $wd ) {
    $day_name         = $initial ? $wp_locale->get_weekday_initial( $wd ) : $wp_locale->get_weekday_abbrev( $wd );
    $wd               = esc_attr( $wd );
    $calendar_output .= "\n\t\t<th scope=\"col\" title=\"$wd\">$day_name</th>";
  }

  $calendar_output .= '
  </tr>
  </thead>
  <tbody>
  <tr>';

  $daywithpost = array();

  // Get days with posts.
  $dayswithposts = $wpdb->get_results(
    "SELECT DISTINCT DAYOFMONTH(post_date)
    FROM $wpdb->posts WHERE post_date >= '{$thisyear}-{$thismonth}-01 00:00:00'
    AND post_type = 'post' AND post_status = 'publish'
    AND post_date <= '{$thisyear}-{$thismonth}-{$last_day} 23:59:59'",
    ARRAY_N
  );

  if ( $dayswithposts ) {
    foreach ( (array) $dayswithposts as $daywith ) {
      $daywithpost[] = (int) $daywith[0];
    }
  }

  // See how much we should pad in the beginning.
  $pad = calendar_week_mod( gmdate( 'w', $unixmonth ) - $week_begins );
  if ( 0 != $pad ) {
    $calendar_output .= "\n\t\t" . '<td colspan="' . esc_attr( $pad ) . '" class="pad">&nbsp;</td>';
  }

  $newrow      = false;
  $daysinmonth = (int) gmdate( 't', $unixmonth );

  for ( $day = 1; $day <= $daysinmonth; ++$day ) {
    if ( isset( $newrow ) && $newrow ) {
      $calendar_output .= "\n\t</tr>\n\t<tr>\n\t\t";
    }
    $newrow = false;

    if ( current_time( 'j' ) == $day &&
      current_time( 'm' ) == $thismonth &&
      current_time( 'Y' ) == $thisyear ) {
      $calendar_output .= '<td id="today">';
    } else {
      $calendar_output .= '<td>';
    }

    if ( in_array( $day, $daywithpost, true ) ) {
      // Any posts today?
      $date_format = gmdate( _x( 'F j, Y', 'daily archives date format' ), strtotime( "{$thisyear}-{$thismonth}-{$day}" ) );
      /* translators: Post calendar label. %s: Date. */
      $label            = sprintf( __( 'Posts published on %s' ), $date_format );
      $calendar_output .= sprintf(
        '<a href="%s" aria-label="%s">%s</a>',
        get_day_link( $thisyear, $thismonth, $day ),
        esc_attr( $label ),
        $day
      );
    } else {
      $calendar_output .= $day;
    }

    $calendar_output .= '</td>';

    if ( 6 == calendar_week_mod( gmdate( 'w', mktime( 0, 0, 0, $thismonth, $day, $thisyear ) ) - $week_begins ) ) {
      $newrow = true;
    }
  }

  $pad = 7 - calendar_week_mod( gmdate( 'w', mktime( 0, 0, 0, $thismonth, $day, $thisyear ) ) - $week_begins );
  if ( 0 != $pad && 7 != $pad ) {
    $calendar_output .= "\n\t\t" . '<td class="pad" colspan="' . esc_attr( $pad ) . '">&nbsp;</td>';
  }

  $calendar_output .= "\n\t</tr>\n\t</tbody>";

  $calendar_output .= "\n\t</table>";

  $calendar_output .= '<nav aria-label="' . __( 'Previous and next months' ) . '" class="wp-calendar-nav">';

  if ( $previous ) {
    $calendar_output .= "\n\t\t" . '<span class="wp-calendar-nav-prev"><a href="' . get_month_link( $previous->year, $previous->month ) . '">&laquo; ' .
      $wp_locale->get_month_abbrev( $wp_locale->get_month( $previous->month ) ) .
    '</a></span>';
  } else {
    $calendar_output .= "\n\t\t" . '<span class="wp-calendar-nav-prev">&nbsp;</span>';
  }

  $calendar_output .= "\n\t\t" . '<span class="pad">&nbsp;</span>';

  if ( $next ) {
    $calendar_output .= "\n\t\t" . '<span class="wp-calendar-nav-next"><a href="' . get_month_link( $next->year, $next->month ) . '">' .
      $wp_locale->get_month_abbrev( $wp_locale->get_month( $next->month ) ) .
    ' &raquo;</a></span>';
  } else {
    $calendar_output .= "\n\t\t" . '<span class="wp-calendar-nav-next">&nbsp;</span>';
  }

  $calendar_output .= '
  </nav>';

  $cache[ $key ] = $calendar_output;
  wp_cache_set( 'get_calendar', $cache, 'calendar' );

  if ( $display ) {
    echo apply_filters( 'get_calendar', $calendar_output );
    return;
  }
  /** This filter is documented in wp-includes/general-template.php */
  return apply_filters( 'get_calendar', $calendar_output );
}

可以看出，这个函数还是挺复杂的。

包含钩子：

apply_filters( 'get_calendar', string $calendar_output )

使用举例：

get_calendar();