How to include today when iterating a DatePeriod? - php

Question

Why is today excluded from the returned values?
SELECT DATE(created) AS reg_date,
COUNT(*) AS user_reg_per_day
FROM users
WHERE created > (NOW() - INTERVAL 30 DAY)
GROUP BY reg_date
My query seems to be fine, but I use following PHP to fill in the gaps:
function generate_calendar_days() {
$end = date("Y-m-d");
$today = strtotime($end);
$start = strtotime("-30 day", $today);
$start = date('Y-m-d', $start);
$range = new DatePeriod(
DateTime::createFromFormat('Y-m-d', $start),
new DateInterval('P1D'),
DateTime::createFromFormat('Y-m-d', $end));
$filler = array();
foreach($range as $date) {
$d = $date->format('Y-m-d');
$filler[$d] = 0;
}
return $filler;
}
My guess is $today is not correct.

Answer 1

There is no reason your query should exclude data from the current day unless there is something odd with the way you are writing data to this table. Are you maybe not seeing it because you are not ordering your results (i.e. it is at bottom of result set)?
It would be giving partial day results for the day 30 days ago. As such, you might consider modifying the WHERE condition a bit:
SELECT DATE(created) AS reg_date,
COUNT(*) AS user_reg_per_day
FROM users
WHERE created >= DATE(DATE_SUB(NOW(),INTERVAL 30 DAY))
GROUP BY reg_date
ORDER BY reg_date DESC
The following is comments on update question, since it seems problem is in PHP code.
I do not fully understand why you would mix strtotime functionality with DateTime, DateInterval, DatePeriod. It is good to see that you are using those though as those are drastically underused by many developers.
That being said I might rewrite that function as:
function generate_calendar_days($start = 'today', $days = 30, $days_in_past = true) {
$dates = array();
try {
$current_day = new DateTime($start); // time set to 00:00:00
} catch (Exception $e) {
echo ('Failed with: ' . $e->getMessage());
return false;
}
$interval = new DateInterval('P1D');
if (true === $days_in_past) {
$interval->invert = 1; // make days step back in time
}
$range = new DatePeriod($current_day, $interval, $days);
foreach($range as $date) {
$dates[] = $date->format('Y-m-d');
}
return $dates;
}
Note that here I have added parameters to make your function more flexible. I also only return an array of date strings so as to make the the function more general purpose. You can leave how to work with the array of dates as an implementation detail outside the scope of this function.
Your zero-filled array can easily be constructed outside the function call like this:
$calendar = array_fill_keys(generate_calendar_days(), 0);

Answer 2

Your sentence is perfect, in fact SELECT (NOW() - INTERVAL 30 DAY) returns 2013-12-18 22:33:30. I experimented similar odd problems, and it was because our DDBB server had a different time configuration than our Apache Server, and it gaves us weird results.
Check your servers time configuration, (http://dev.mysql.com/doc/refman/5.5/en/time-zone-support.html)

Answer 3

You can see from the comments in the PHP manual that people have had the trouble including the end date when iterating a DatePeriod. There are various modifications suggested there that can help with that, but for what you're doing you don't really need the end date, since you're always just going back a set number of days from the current date.
You can include the end date by using the "recurrences" form of the DatePeriod constructor.
function generate_calendar_days(int $n): array
{
$range = new DatePeriod(new DateTime("-$n day"), new DateInterval('P1D'), $n);
foreach($range as $date) {
$filler[$date->format('Y-m-d')] = 0;
}
return $filler;
}
$days = generate_calendar_days(30);