Open Exchange Rates offers a data currency API to interact with your application. I used their API on the Currency Converter application I built.
Today, I’m going to write a PHP class that will interact with Open Exchange Rate’s API and will return a key-value pair array of currency rates.
class OpenExchange {
protected $app_id;
public function __construct($app_id){
$this->app_id = $app_id;
}
}
We start with declaring the $app_id. Open Exchange Rates will provide you with an “Application ID” needed to call their API.
Instantiating the OpenExchange class will require a value for $app_id.
Next, I’m going to create a function that will actually call the current currency exchange rates.
class OpenExchange {
protected $app_id;
public function __construct($app_id){
$this->app_id = $app_id;
}
public function getRates(){
$app_id = $this->app_id;
$file = "latest.json";
header("Content-Type: application/json");
$json = file_get_contents("http://openexchangerates.org/api/{$file}?app_id={$app_id}");
$obj = json_decode($json);
$rate_container = array();
if(isset($obj->{"rates"})){
foreach($obj->{"rates"} as $key=>$rate){
$rate_container[$key]=$rate;
}
}
return $rate_container;
}
}
Using PHP’s file_get_contents function, getRates will call the Open Exchange Rate API that returns a JSON format.
Then it will validate the returned JSON data if it has a “rate” property and is not empty. If validation passes, function will loop through each of the “rate” items key-value pair to store them in a key-value PHP array $rate_container.
I use the OpenExchange class like this,
$app_id = "my_open_exchange_rate_key";
$open_exchange = new OpenExchange($app_id);
$current_rates = $open_exchange->getRates();
Printing out the returned array on the console,
Array
(
[AED] => 3.67
[AFN] => 68.56
[ALL] => 122.8861
[AMD] => 476.506667
..................... more
)
Next step would be to use this freshly fetch data. I could update stored currency rates on my database using this function.
public function updateCurrencyRates($conn,$current_rates){
$conn->beginTransaction();
try{
foreach($current_rates as $currency_code=>$rate){
$code = trim(strtolower($currency_code));
$count = $conn->executeUpdate("UPDATE currencies SET rate = ? WHERE TRIM(LOWER(code)) = ?", array($rate, $code));
if($count > 0){
echo "Updated:".$currency_code." = ".$rate."\n";
}
else{
echo "No update:".$currency_code."\n";
}
}
$conn->commit();
return "Completed update process.";
}catch(\Exception $e){
print_r($e);
}
}
Check-out the whole OpenExchange class here.