浏览json并计算值

Question

Good night. I'm trying to access all of the availableForExchange values ​​on the return of a page below:

[
   {
      "code":"18707498",
      "date":"2019-01-23T16:58:01",
      "totalPriceInCents":14450,
      "orderTotalPriceInCents":14450,
      "status":"PGTO_NAO_CONFIRMADO",
      "availableForExchange":false,
      "paymentType":"CREDIT_CARD",
      "installmentValueInCents":7225,
      "installmentsNumber":2,
      "paymentSummaries":[
         {
            "paymentType":"CREDIT_CARD",
            "installmentsNumber":2,
            "installmentValueInCents":7225,
            "valueInCents":14450
         }
      ],
      "hasGiftCard":false
   },
   {
      "code":"019741817156",
      "date":"2017-06-11T19:09:06",
      "totalPriceInCents":19110,
      "orderTotalPriceInCents":19110,
      "status":"ENTREGA_EFETUADA",
      "availableForExchange":false,
      "paymentType":"CREDIT_CARD",
      "installmentValueInCents":9555,
      "installmentsNumber":2,
      "paymentSummaries":[
         {
            "paymentType":"CREDIT_CARD",
            "installmentsNumber":2,
            "installmentValueInCents":9555,
            "valueInCents":19110
         }
      ],
      "hasGiftCard":false
   }
]

I have already tried the following ways:

$data = curl_exec($ch);
$json = json_decode($data, true);
$str = $json['availableForExchange'];
print_r($str);

I need to access all values ​​of: availableForExchange , search for true values ​​and count (if true), and save to a variable.

Answer 1

what you want to do is to filter the $json (it is an array)

$found = array_filter($json, function($entry) { return $entry['availableForExchange']; });

echo 'Entries: '.count($found);
print_r($found);

Answer 2

By using array_column to access the availableForExchange values directly, you can use array_filter with no callback (since the values in that column are boolean):

$json = json_decode($data, true);
$available = count(array_filter(array_column($json, 'availableForExchange')));
echo "$available available for exchange\n";

Output (for your sample data)

0 available for exchange

Demo on 3v4l.org