PHP loop to retrieve each instance of a specific piece of data from within decoded JSON

Question

I'm trying to write a loop that will list all the uid in the JSON data. The uid spans two categories (shirts and pants). Below is what I have so far. Any help is greatly appreciated.

Current Code and JSON

$url = 'http://foothillertech.com/student/webdesign/2018/2018benrud2/projects/retail/data2.json';
$jsonData = file_get_contents($url);
$data = json_decode($jsonData, true);

I can get each uid manually with this - $data['shirts'][0]['uid'] , but I'm looking for a way to loop through the data to return all uid's from both the shirts and pants category.

Thank you!

This is the code that solved my problem.

Thank you @Don't Panic for your help!

foreach ($data as $item_type => $items) {
    foreach ($items as $item) {
        $uids[] = $item['uid'];
        echo $uids[$i]."<br>";
        $i++;
    }
}

Answer 1

You can merge the second level arrays (shirts and pants keys) and take the uid column from the result of that.

$uids = array_column(array_merge(...array_values($data)), 'uid');

Details of this expression from inside out (PREVIOUS indicates result of previous step):

• array_values($data) converts the string keys of the outer array ('shirts', 'pants') to numeric
• array_merge(... PREVIOUS ) merges the two inner arrays, passing them to array_merge using argument unpacking . (The previous array_values step is needed because argument unpacking won't work on arrays with string keys.)
• array_column( PREVIOUS , 'uid') takes all the 'uid' values from the merged array produced by the previous steps

---

This is sort of a fancy way of doing something fairly simple, though. The code will be more clear if you just use a nested loop.

foreach ($data as $item_type => $items) {
    foreach ($items as $item) {
        $uids[] = $item['uid'];
    }
}

Answer 2

As @jon-stirling mentioned it, you can use array_column() to extract values from a sign column of an array. It does many others things that are beyond the scope of your question. Check it out at http://php.net/manual/en/function.array-column.php

Specifically for your example, the following code should give you all the uid extracted from $data['shirts'] .

$url = 'http://foothillertech.com/student/webdesign/2018/2018benrud2/projects/retail/data2.json';
$jsonData = file_get_contents($url);
$data = json_decode($jsonData, true);
$shirtsUids = array_column($data['shirts'], 'uid');
$pantsUids = array_column($data['pants'], 'uid');

// Then you can use $shirtsUids and $pantsUids as you see fit.

Make sure that the $data array has a key called shirt or else you will have an error or warning thrown.

To avoid causing an error, I using use the Null coalescing operator ( ?? ) to make uncertain values default to an acceptable one. So I will use $data['shirts'] ?? [] $data['shirts'] ?? [] . But again, make sure that $data['shirts'] is an array.

$url = 'http://foothillertech.com/student/webdesign/2018/2018benrud2/projects/retail/data2.json';
$jsonData = file_get_contents($url);
$data = json_decode($jsonData, true);
$shirtsUids = array_column($data['shirts'] ?? [], 'uid');
$pantsUids = array_column($data['pants'] ?? [], 'uid');

// Then you can use $shirtsUids and $pantsUids as you see fit.