DO I need foreach for accessing specific array data here?

[Rascalsailor]

Hi all

I have the following file of json data (json_file.json):

{
	"name": "as.up.data.forward",
	"time": "2022-07-27T09:46:50.565402155Z",
	"identifiers": [{
		"device_ids": {
			"device_id": "my_arduino-device",
			"application_ids": {
				"application_id": "mydevicename"
			},
			"dev_eui": "012345678910",
			"join_eui": "109876543210",
			"dev_addr": "123456"
		}
	}]
}
	

I am using the following code to extract and display some of the data:

<?php

$json = file_get_contents('json_file.json');

// Decode the JSON file
$json_data = json_decode($json,true);

$identifiers_array = ($json_data['identifiers']);

foreach($identifiers_array as $elem)  {
   print_r($elem['device_ids']['application_ids']['application_id']);
   echo("<br/>");   
   print_r($elem['device_ids']['dev_eui']);
   echo("<br/>");
   print_r($elem['device_ids']['device_id']);
}


?>

The output as expected, shows:

mydevicename
012345678910
my_arduino-device

My Question is:

Can I not avoid the use of the foreach by doing something along the lines of:

  print_r($identifiers_array['device_ids']['application_ids']['application_id']);

(can I not point to a specific element?)

I'm really just wondering if I am following a 'best practice' method here.

Thanks

Russell

[Barand]

1 hour ago, Rascalsailor said:

(can I not point to a specific element?)

Of course you can.

foreach() is for iterating through all elements in an array. In this case you don't want to do that.

$arr = json_decode($jsn, 1);
$elem = $arr['identifiers'][0]['device_ids'];

echo $elem['application_ids']['application_id'] . '<br>';
echo $elem['dev_eui'] . '<br>';
echo $elem['device_id'] . '<br>';

However, are you certain that the "identifiers" array will only have a single element? If the number is unknown, use foreach()...

$arr = json_decode($jsn, 1);
foreach ( $arr['identifiers'] as $ids ) {
    $elem = $ids['device_ids'];
    echo $elem['application_ids']['application_id'] . '<br>';
    echo $elem['dev_eui'] . '<br>';
    echo $elem['device_id'] . '<br>';
}

 

[Rascalsailor]

Great, thanks for the reply. The trick was to use: $elem = $arr['identifiers'][0]['device_ids'];

That indexing : [0] was confusing me.

regards

Russell

Edited July 29, 2022 by Rascalsailor

[Barand]

Use

echo '<pre>' . print_r($arr, 1) . '</pre>';

to give a readable formatted display of your array.  Then follow the chain of keys...