PHP: Nested json and value extraction

Question

I have this json below. I'm trying to get values using json_decode. I'm getting some of the values, but I'm having trouble with the deeply nested values. Here is the json:

{
"startAt": 0,
"issue": [
{
    "id": "51526",
    "fields": {
        "people": [
            {
                "name": "bob",
                "emailAddress": "[email protected]",
                "displayName": "Bob Smith",
            },
            {
                "name": "john",
                "emailAddress": "[email protected]",
                "displayName": "John Smith",
            }
        ],
        "skill": {
            "name": "artist",
            "id": "1"
        }
    }
},
{
    "id": "2005",
    "fields": {
        "people": [
            {
                "name": "jake",
                "emailAddress": "[email protected]",
                "displayName": "Jake Smith",
            },
            {
                "name": "frank",
                "emailAddress": "[email protected]",
                "displayName": "Frank Smith",
            }
        ],
        "skill": {
            "name": "writer",
            "id": "2"
        }
    }
}
]

}

I know I can get one value by doing this:

foreach ($decoded_array['issue'][0]['fields']['people'] as $person) {
  echo $person['emailAddress'];
}

However, is there a simplistic way to get all the "emailAddresses" for bob,john,jake, and frank?

Thanks!

Answer 1

The easiest way really is just to loop, but nest loops first at $decoded_array['issue'] and then an inner loop over ['people']. Collect your addresses into an output array.

// Note: this assumes you called json_decode() with the second
// param TRUE to force an associative array..
// $decoded_array = json_decode($input_json, TRUE);

$addresses = array();
foreach ($decoded_array['issue'] as $i) {
  foreach ($i['fields']['people'] as $person) {
    // Append the address onto an output array
    $addresses[] = $person['emailAddress'];
  }
}
// De-dupe them if necessary
$addresses = array_unique($addresses);
print_r($addresses);

// Prints
Array
(
    [0] => [email protected]
    [1] => [email protected]
    [2] => [email protected]
    [3] => [email protected]
)

A slightly fancier method if you weren't certain of the structure except that the keys are named emailAddress would be to use array_walk_recurisve() to traverse the array looking for that key. This will collect all keys named emailAddress, not just those inside the ['people'] subarrays.

$addresses = array();
// Pass $addresses into the closure by reference so you can write to it
array_walk_recursive($decoded_array, function($value, $key) use (&$addresses) {
  // Find *all keys* called emailAddress
  if ($key == 'emailAddress') {
    $addresses[] = $value;
  }
});