array of objects selecting object based on attribute value - php

Question

I am working with the Mailchimp API at the moment, I have a list of campaigns that have been run, or are due to be run, and I wanting to get the link for the most recently run campaign. How would I go about comparing the attribute "send_time" to find the most recent and it's attributed parent object?
The campaigns array looks like this,
{
"campaigns": [
{
"id": 1,
"type": "regular",
"status": "save",
"send_time": ""
},
{
"id": 2,
"type": "regular",
"status": "sent",
"send_time": "2015-11-11T14:42:58+00:00"
},
{
"id": 3,
"type": "regular",
"status": "sent",
"send_time": "2016-01-01T14:42:58+00:00"
},
{
"id": 4,
"type": "regular",
"status": "sent",
"send_time": "2016-06-12T14:42:58+00:00"
}
]
}
So in that above array, the final object has the most recent send_time, how would I assess this, and then grab that object? I have a semi solution, but it seems long winded.
<?php
//Build an array of send_times
$dates = [];
foreach($result['campaigns'] as $campaign) {
$dates[$campaign['id']] = $campaign['send_time'];
}
//Get the most recent date
$mostRecent = 0;
foreach($dates as $k => $v) {
$curDate = strtotime($v);
if($curDate > $mostRecent) {
$mostRecent = $curDate
$currentId = $k;
}
}
//Get the object
foreach($results['campaigns'] as $campaign) {
if($campaign['id'] == $currentId) {
$c = $campaign;
}
}
?>

Answer 1

Use array_multisort() like below (single line code):-
<?php
$data = '{
"campaigns": [
{
"id": 1,
"type": "regular",
"status": "save",
"send_time": ""
},
{
"id": 2,
"type": "regular",
"status": "sent",
"send_time": "2015-11-11T14:42:58+00:00"
},
{
"id": 3,
"type": "regular",
"status": "sent",
"send_time": "2016-01-01T14:42:58+00:00"
},
{
"id": 4,
"type": "regular",
"status": "sent",
"send_time": "2016-06-12T14:42:58+00:00"
}
]
}';
$array = json_decode($data,true)['campaigns']; // decode json string to array
array_multisort($array,SORT_DESC, SORT_STRING); // use of array_multisort
echo "<pre/>";print_r($array); // this will returns you indexed array like 0,1,2... you can again convert it to campaigns array like $final_array['campaigns'] = $array;
?>
Output:- https://eval.in/598349
Note:-
1.If your given data is in array already then no need to use json_decode(), directly use array_multisort() on it
https://eval.in/598355
For more reference:-
http://sg2.php.net/manual/en/function.array-multisort.php

Answer 2

<?php
$dates = [];
$recent_campaign = null;
$recent_time = 0;
foreach($result['campaigns'] as $campaign) {
$curDate = strtotime($campaign['send_time']);
if($curDate > $recent_time) {
$recent_time = $curDate
$recent_campaign = $campaign;
}
}
//$recent_campaign is the most recent campaign
?>
You can try this approach. Else you can use usort by send_time (direct solution).
I have not executed this code!

Answer 3

You can sort your objects by that property (I'd suggest usort, so that you can define your own sorting) and then get the first item in that array.
usort($result, function ($campaign1, $campaign2) {
if ($campaign1['send_time'] == $campaign2['send_time']) {
return 0;
}
return (strtotime($campaign1['send_time']) > strtotime($campaign2['send_time'])) ? -1 : 1;
});
$mostRecentCampaign = $campaign[0];
Note: I haven't run this, so you might have to tweak the return on the compare function if it's sorting in the wrong order.

Answer 4

If you just want to grab the max element and want to use fewer lines of code, try this:
Grab the max time by mapping the "send time" column to an epoch time and getting the max value
Filter your array by the entries that correspond to that max time
Profit
Example:
$dataArray = /* your array */
$maxTime = max(array_map('strtotime',array_column($dataArray["campaigns"], 'send_time')));
$maxEntry = array_filter($dataArray["campaigns"], function ($arr) use ($maxTime) { return strtotime($arr["send_time"])==$maxTime; });
print_r($maxEntry);
Would print:
Array
(
[3] => Array
(
[id] => 4
[type] => regular
[status] => sent
[send_time] => 2016-06-12T14:42:58+00:00
)
)
Note The advantage of this is that it doesn't need sorting. The disadvantage is that sorting and then getting the last element would be faster. However with sorting you lose the original array order which is sometimes needed.