Collect currency exchange rates in a MySQL database with PHP and fixer.io API

Posted on 4. August 2015 Comments

If you work in a company that buys and sells goods in many different currencies, it might be a good idea, to use the latest exchange rates. Also, it might be useful, to store old exchange rates to clarify/verify old business decisions. If once a day is enough for you, fixer.io offers a free simple Rest API. A lot of the code at my work is written in PHP but I usually use the request library in JavaScript and Python, so I’m using it in this example too. A common PHP solution would be guzzle. But first, get composer (the PHP counterpart to npm or pip):

$ curl -sS https://getcomposer.org/installer | php

$ php composer.phar require rmccue/requests

The mysql_ commands are deprecated (and removed in PHP 7), use mysqli or PDO. Also you should use some sort of framework for the database access, like medoo or a proper ORM. This is just proof of concept.


$base = 'EUR';
$request = Requests::get('https://api.fixer.io/latest?base=' . $base, array('Accept' => 'application/json'));
if ($request->status_code == 200) {
$response = json_decode($request->body);
$GBP = $response->rates->GBP;
$CAD = $response->rates->CAD;
$USD = $response->rates->USD;
$NOK = $response->rates->NOK;
$CNY = $response->rates->CNY;
$rBase = mysql_real_escape_string($response->base);
$date = mysql_real_escape_string($response->date);
$currencies = mysql_real_escape_string("1.0, $USD, $GBP, $NOK, $CNY, $CAD");
$qry = "INSERT INTO `exchange_rates_fixerio`(date, base, eur, usd, gbp, nok, cny, cad) VALUES ('$date', '$rBase', $currencies);";
$insert = mysql_query($qry, $mysqlConnection) or print mysql_error();
}

I assume the database connection is defined earlier, there’s lot’s of documentation for that. Because we are from Europe, I chose Euro (EUR) as the base currency. Apart from the get() method, you need nothing else, to send a request. If the request returns an OK(200), the response is read and saved into different variables, e.g. for British Pounds, US Dollar, Canadian Dollar, Chinese Renminbi and Norwegian Krone. Just to make sure we have the right base, it’s also parsed. From there it’s only a simple INSERT INTO (as said before, use a framework for that)

The table could look like this:

CREATE TABLE `echange_rates_fixerio` (
`date` date NOT NULL,
`base` varchar(3) NOT NULL,
`eur` double NOT NULL,
`usd` double NOT NULL,
`gbp` double NOT NULL,
`nok` double NOT NULL,
`cny` double NOT NULL,
`cad` double NOT NULL
)

 

You can also find this code on GitHub.

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