URL中的解析日期并不总是可用（触发空白屏幕）

Question

I'm trying to parse data (for filtering) from an URL. I want to be able to use http://domain.com/page.php?startDate=20150101&endDate=20150927. In this example, data is used/visible/calculated from 1 January till 27 September.

When the endDate is entered/changed, that date is properly used in a filter. If it's not entered todays date should be used (but that's where it goes wrong). For that I use the following code:

    $endDateFormat = DateTime::createFromFormat('Ymd', htmlspecialchars($query['endDate']));
    $endDate = $endDateFormat->format('Y-m-d'); // change YYYYMMDD to YYYY-MM-DD for MySQL.

    if (empty($endDate)) {
        $endDate = date('Y-m-d'); // Use todays date if date is not entered.
    } elseif ($endDate >= date('Y-m-d')) {
        $endDate = date('Y-m-d'); // Use todays date if date is newer than today.
    }

For an unknown reason the endDate must be added in the URL. If it isn't used, the page is blank. If entered, the code works as supposed: when you use 31-12-2015 as endDate it is automatically corrected to today (you cannot get data from the future, of course) and when you use a date earlier than today that date is used. I verified this by checking the calculations and simply an echo from $endDate.

I don't know how to proceed now to prevent a blank page. The purpose is to use todays date as endDate if you get at http://domain.com/page.php (and thus endDate is empty/NULL/not in the URL).

This issue also appears with the startDate, but I'm quite sure it has the same cause.

Answer 1

I've started from scratch (yet again) and found the solution that worked for me with less code. Not sure why I didn't find it sooner or what went wrong with the earlier 'restarts', but the following works as I want to:

        $endDate = htmlspecialchars($query['endDate']);
    if (empty($endDate)) {
        $endDate = date('Ymd');
    } elseif ($endDate >= date('Ymd')) {
        $endDate = date('Ymd');
    }