Cannot retrieve results from amazon mws products api - php

Question

Using the below code, the only result I can get to echo is the URL. When I copy and paste into browser, I get:
<Message>
The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.
Code Being Used;
<?php
date_default_timezone_set('America/New_York');
define('AWS_ACCESS_KEY_ID', '***');
define('AWS_SECRET_ACCESS_KEY', '***');
define('APPLICATION_NAME', 'test');
define('APPLICATION_VERSION', '1.0');
define ('MERCHANT_ID', '***');
define ('MARKETPLACE_ID', '***');
$base_url = "https://mws.amazonservices.com/Products/2011-10-01";
$method = "GET";
$host = "mws.amazonservices.com";
$uri = "/Products/2011-10-01";
function amazon_xml($searchTerm) {
$params = array(
'AWSAccessKeyId' => AWS_ACCESS_KEY_ID,
'Action' => "GetCompetitivePricingForASIN",
'SellerId' => MERCHANT_ID,
'SignatureMethod' => "HmacSHA256",
'SignatureVersion' => "2",
'Timestamp'=> gmdate("Y-m-d\TH:i:s.\\0\\0\\0\\Z", time()),
'Version'=> "2011-10-01",
'MarketplaceId' => MARKETPLACE_ID,
'Query' => $searchTerm,
'QueryContextId' => "Automotive");
// Sort the URL parameters
$url_parts = array();
foreach(array_keys($params) as $key)
$url_parts[] = $key . "=" . str_replace('%7E', '~', rawurlencode($params[$key]));
sort($url_parts);
// Construct the string to sign
$url_string = implode("&", $url_parts);
$string_to_sign = "GET\nmws.amazonservices.com\n/Products/2011-10-01\n" . $url_string;
// Sign the request
$signature = hash_hmac("sha256", $string_to_sign, AWS_SECRET_ACCESS_KEY, TRUE);
// Base64 encode the signature and make it URL safe
$signature = urlencode(base64_encode($signature));
$url = "https://mws.amazonservices.com/Products/2011-10-01" . '?' . $url_string . "&Signature=" . $signature;
$ch = curl_init();
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
$response = curl_exec($ch);
echo $url;
// return $xml if you still want to parse the data elsewhere
$xml = simplexml_load_string($response);
// return this if you just want the raw XML string
return $xml->asXML();
echo $xml->GetMatchingProductResult->Product->Identifiers->MarketplaceASIN->ASIN;
}
$searchTerm = "B00FNNLBK2";
amazon_xml($searchTerm);
//foreach ($xml->GetMatchingProductResult->Product as $product) {
// do something for each <Product>, such as output the ASIN...
//}
echo $xml;
echo $searchTerm;
echo $xml->GetMatchingProductResult->Product->Identifiers->MarketplaceASIN->ASIN;
echo $url;
?>
I did verify multiple times that the sign in credentials are correct, with no absract leading or trailing space.

Answer 1

Those parameters (e.g. Query and QueryContextId) don't match with the Action you are trying to call (GetCompetitivePricingForASIN). They correspond to the ListMatchingProducts action.
Assuming that you meant ListMatchingProducts try this:
<?php
date_default_timezone_set('America/New_York');
define('AWS_ACCESS_KEY_ID', '***');
define('AWS_SECRET_ACCESS_KEY', '***');
define('APPLICATION_NAME', 'test');
define('APPLICATION_VERSION', '1.0');
define ('MERCHANT_ID', '***');
define ('MARKETPLACE_ID', '***');
function amazon_xml($searchTerm)
{
$params = array(
'AWSAccessKeyId' => AWS_ACCESS_KEY_ID,
'Action' => "ListMatchingProducts",
'SellerId' => MERCHANT_ID,
'SignatureMethod' => "HmacSHA256",
'SignatureVersion' => "2",
'Timestamp' => gmdate("Y-m-d\TH:i:s.\\0\\0\\0\\Z", time()),
'Version' => "2011-10-01",
'MarketplaceId' => MARKETPLACE_ID,
'Query' => $searchTerm,
'QueryContextId' => "Automotive"
);
$url_parts = array();
foreach (array_keys($params) as $key)
$url_parts[] = $key . "=" . str_replace('%7E', '~', rawurlencode($params[$key]));
sort($url_parts);
$url_string = implode("&", $url_parts);
$string_to_sign = "GET\nmws.amazonservices.com\n/Products/2011-10-01\n" . $url_string;
$signature = hash_hmac("sha256", $string_to_sign, AWS_SECRET_ACCESS_KEY, TRUE);
$signature = urlencode(base64_encode($signature));
$url = "https://mws.amazonservices.com/Products/2011-10-01" . '?' . $url_string . "&Signature=" . $signature;
$ch = curl_init();
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
$response = curl_exec($ch);
$xml = simplexml_load_string($response);
return $xml->asXML();
}
$searchTerm = "B00FNNLBK2";
echo amazon_xml($searchTerm);
You can find the relevant parameters for each Action in the MWS documentation e.g. here:
http://docs.developer.amazonservices.com/en_US/products/Products_GetCompetitivePricingForASIN.html
You can also see them using the MWS Scratchpad:
https://mws.amazonservices.com/scratchpad/index.html