如何使用键而不是数组索引从 JSON 数组中获取值

Question

I have a JSON that I can comfortably get the values from.

However, on the array part, I'd want to get the values using the value instead of the index.

$st = '{
   "Body":{
      "stkCallback":{
         "MerchantRequestID":"10832-3081608-1",
         "ResultCode":0,
         "ResultDesc":"The service request is processed successfully.",
         "CallbackMetadata":{
            "Item":[
               {
                  "Name":"Amount",
                  "Value":2.0
               },
               {
                  "Name":"ReceiptNumber",
                  "Value":"OEH49B3LZU"
               }
            ]
         }
      }
   }
}';

$callbackData = json_decode($st);
echo $callbackData->Body->stkCallback->CallbackMetadata->Item[0]->Value; //works well but this index number could change
echo $callbackData->Body->stkCallback->CallbackMetadata->Item[1]->Value; //works well but this index number could change

Can I get the values using say Amount and ReceiptNumber instead of the index as above?

Answer 1

If you are just fetching odd values (1 or 2) then you can loop through the items and compare the name with the one you are after, then you can extract the corresponding value...

$name = "Amount";
foreach ( $callbackData->Body->stkCallback->CallbackMetadata->Item as $item )   {
    if ( $item->Name == $name ) {
        echo $item->Value;
    }
}

If there was a block of data and you want to use it in various places, it's quicker to extract the values (using array_column() ) and index it by the name...

$data = array_column($callbackData->Body->stkCallback->CallbackMetadata->Item, 
           "Value", "Name");
print_r($data);

This for your example data gives...

Array
(
    [Amount] => 2
    [ReceiptNumber] => OEH49B3LZU
)