Row highlighting based on due date using php - php

Question

I'm relatively new to PHP, I've learned procedural PHP and I'm playing around with an app.
I've Looked around the site and found a few samples on date formatting and highlighting using PHP, HTML and CSS.
With the help found here and the PHP manual, I've put together some code to highlight 2 different rows among many others provided by a database that follow this criteria:
Anything due in 1 day (today, yesterday, last week, etc.) should color the table row red.
Anything 3 days out (between 1 day and 3 days in the future) should color the table row yellow.
Anything else should utilize the bootstrap "table-striped" styling.
Here is the code I've put together
//Today + 1 day
$oneDay = date('m/d/Y', strtotime("+1 day"));
//Today + 3 days
$threeDays = date('m/d/Y', strtotime("+3 days"));
//Database entry for comparison
$due = date_create($record['projected_delivery']);
$dueOneDay = date_create($oneDay);
$dueThreeDays = date_create($threeDays);
//Get the difference between the 2 dates
$diffOne = date_diff($due, $dueOneDay);
$diffThree = date_diff($due, $dueThreeDays);
if ($diffThree->format('%d') < 3) {
$highlight_css = " warning";
}elseif ($diffOne->format('%d') <= 1){
$highlight_css = " danger";
}else {
$highlight_css = "";
}
I then add the $highlight_css to the HTML.
So far some of the functionality is working. Proper highlighting is not added for:
Dates older than 1 day (i.e. yesterday, last week)
How can this functionality be achieved?

Answer 1

I would use this instead:
<?php
$dueDates =["06/05/2017","06/06/2017","06/07/2017","06/08/2017","06/09/2017","06/10/2017","06/11/2017","06/12/2017"];
$table = "<table class='table table-bordered'><thead><tr><th>Date</th></tr></thead><tbody>";
$today = date_create(date('m/d/Y')); // example: 06/07/2017
foreach ($dueDates as $dueStr) {
$due = date_create($dueStr);
$diff = date_diff($today, $due)->format("%r%a");
$highlight_css = "";
if ($diff > 1 && $diff <= 3) {
$highlight_css = " warning";
} elseif ($diff == 1) {
$highlight_css = " danger";
}
$table .= "<tr class='$highlight_css'><td>$dueStr</td></tr>";
}
$table .= "</tbody></table>";
?>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" >
<?php
echo $table;

Answer 2

$diffThree->format('%d')
will return a string instead of an integer. In order to compare it correctly with other numbers (3 and 1 in your case) you need to convert it to an int:
(int) $diffThree->format('%d')
and
(int) $diffOne->format('%d')

Answer 3

The issue
A DateInterval (the return value of date_diff()) has the number of days (actually stored in a property d, which could be used instead of getting a string with format()), which should always be a positive number. And for dates before today's date, the first date diff (i.e. $diffOne) will be 2+ days and the second date diff (i.e. $diffThreeDays) will be 4+ (see this playground example with debugging output above the table) so days before today's date will never be associated with either 'warning' or 'danger' according to the given logic.
A Solution
One approach (perhaps simpler) to comparing the dates is to use DateTime comparison
Note:
As of PHP 5.2.2, DateTime objects can be compared using comparison operators.1
So compare the DateTime variables (i.e. $due with $dueOneDay and $dueThreeDays) instead of the date differences.
In the logic below, you will notice that the order of the comparisons has been reversed, so the check for one day difference comes before the check for three days difference, in order to avoid the danger case never happening.
if ($due < $dueOneDay){
$highlight_css = " danger";
}else if ($due <= $dueThreeDays) {
$highlight_css = " warning";
}else {
$highlight_css = "";
}
With this approach, there is no need for the date_diff variables (i.e. $diffOne, $diffThree).
See a demonstration of this in this playground example.
1http://php.net/manual/en/datetime.diff.php#example-2524