PHP：从复杂的JSON对象获取元素

Question

I'm trying to create a trading bot and at this point I should get the current market value for a cryptocurrency market.

At this point I would like to get the nested parameter "Last" in this JSON array:

array(3) { ["success"]=> bool(true) 
           ["message"]=> string(0) "" 
           ["result"]=> array(1) { 
                  [0]=> array(13) { ["MarketName"]=> string(8) "USDT-BTC" 
                                    ["High"]=> float(17399.99999999) 
                                    ["Low"]=> float(16166) 
                                    ["Volume"]=> float(7200.55684465)                    
                                    ["Last"]=> float(16486.5864853) 
                                    ["BaseVolume"]=> float(119420929.2692) 
                                    ["TimeStamp"]=> string(21) "2017-12-12T20:36:19.2"                          ["Bid"]=> float(16484)  
                                    ["Ask"]=> float(16486.5864853)                    
                                    ["OpenBuyOrders"]=> int(12858) 
                                    ["OpenSellOrders"]=> int(5529) 
                                    ["PrevDay"]=> float(17369.85623056) 
                                    ["Created"]=> string(23) "2015-12-11T06:31:40.633" 
                                   } 
                                }
             }

How can i get it and display it?

This is the script where i get and decode the array

  private function send($method = null , $args = array() , $secure = true) {
  if(empty($method)) return array("status" => false , "error" => "method was not defined!");

  if($secure) $args["apikey"] = $this->apiKey;
  $args["nonce"] = time();

  $urlParams  = array();
  foreach($args as $key => $val) {
    $urlParams[]  = $key . "=" . $val;
  }

  $uri  = $this->baseUrl . $method;

  $argsString = join("&" , $urlParams);
  if(!empty($urlParams)) {
      $uri  = $uri . "?" . $argsString;
  }

  $sign = $secure == true ? hash_hmac('sha512',$uri,$this->apiSecret) : null;

  $uri = trim(preg_replace('/\s+/', '', $uri));
  $ch = curl_init($uri);
  if($secure) curl_setopt($ch, CURLOPT_HTTPHEADER, array('apisign:'.$sign));
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  $execResult = curl_exec($ch);

  if(curl_error($ch))
  {
      return array("status" => false , "error" => curl_error($ch));
  }

  $obj = json_decode($execResult, true);
  return $obj["result"];

I succeeded in displaying the parameter ["result"]: how can i display something nested inside it? Thank you in advance.

Answer 1

Similar to the way you accessed the 'result' element of the initial array, you can access the 'last' element in the nested array like this:

$obj['result'][0]['Last'];

You're first looking at $obj['result'] which is an array and then accessing element 0, which is also an array. You're then accessing the key 'last' on this array.

Answer 2

You could test to see if $obj["result"] is an array then iterate on it, and continue drilling down until you find the thing you want.

if(is_array($obj["result"])) {
    foreach($obj["result"] as $key => $thing) {
          // do something with the $thing
          // or do a 'defined()' check to see if the key(s)
          // inside the object are there.   
          if(isset($thing["Last"])) {
              // do something fancy with your new found info..  
          }
    }
}

or just try to address it directly

$obj["result"][0]["Last"]