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问题:

I try to get prices of an ASIN number with the Amazon Product Advertising API.

Code:

    $artNr = "B003TKSD8E";
    $base_url = "http://ecs.amazonaws.de/onca/xml";
    $params = array(
        'AWSAccessKeyId' => self::API_KEY,
        'AssociateTag' => self::API_ASSOCIATE_TAG,
        'Version' => "2010-11-01",
        'Operation' => "ItemLookup",
        'Service' => "AWSECommerceService",
        'Condition' => "All",
        'IdType' => 'ASIN',
        'ItemId' => $artNr);


    $params['Timestamp'] = gmdate("Y-m-d\TH:i:s.\\0\\0\\0\\Z", time());

    $url_parts = array();
    foreach(array_keys($params) as $key)
        $url_parts[] = $key . "=" . str_replace('%7E', '~', rawurlencode($params[$key]));
    sort($url_parts);

    $url_string = implode("&", $url_parts);
    $string_to_sign = "GET\necs.amazonaws.de\n/onca/xml\n" . $url_string;

    $signature = hash_hmac("sha256", $string_to_sign, self::API_SECRET, TRUE);

    $signature = urlencode(base64_encode($signature));

    $url = $base_url . '?' . $url_string . "&Signature=" . $signature;

    $response = file_get_contents($url);
    $parsed_xml = simplexml_load_string($response);

I think this should be correct - but I don't get offers in the response:

<?xml version="1.0" ?>
  <ItemLookupResponse xmlns="http://webservices.amazon.com/AWSECommerceService/2010-11-01">
    <OperationRequest>
      <RequestId>*********************</RequestId>
      <Arguments>
        <Argument Name="Condition" Value="All">
      </Argument>
        <Argument Name="Operation" Value="ItemLookup">
      </Argument>
        <Argument Name="Service" Value="AWSECommerceService">
      </Argument>
        <Argument Name="ItemId" Value="B003TKSD8E">
      </Argument>
        <Argument Name="IdType" Value="ASIN">
      </Argument>
        <Argument Name="AWSAccessKeyId" Value="*********************">
      </Argument>
        <Argument Name="Timestamp" Value="2011-11-29T01:49:01.000Z">
      </Argument>
        <Argument Name="Signature" Value="*********************">
      </Argument>
        <Argument Name="AssociateTag" Value="*********************">
      </Argument>
        <Argument Name="Version" Value="2010-11-01">
      </Argument>
    </Arguments>
      <RequestProcessingTime>0.0083130000000000</RequestProcessingTime>
    </OperationRequest>
    <Items>
      <Request>
        <IsValid>True</IsValid>
        <ItemLookupRequest>
          <Condition>All</Condition>
          <IdType>ASIN</IdType>
          <ItemId>B003TKSD8E</ItemId>
          <ResponseGroup>Small</ResponseGroup>
          <VariationPage>All</VariationPage>
        </ItemLookupRequest>
      </Request>
      <Item>
        <ASIN>B003TKSD8E</ASIN>
        <DetailPageURL>http://www.amazon.de/Apple-iPhone-4-32GB-schwarz/dp/B003TKSD8E%3FSubscriptionId%3DAKIAI6NFQHK2DQIPRUEQ%26tag%3Dbanholzerme-20%26linkCode%3Dxm2%26camp%3D2025%26creative%3D165953%26creativeASIN%3DB003TKSD8E</DetailPageURL>
        <ItemLinks>
          <ItemLink>
            <Description>Add To Wishlist</Description>
            <URL>http://www.amazon.de/gp/registry/wishlist/add-item.html%3Fasin.0%3DB003TKSD8E%26SubscriptionId%3DAKIAI6NFQHK2DQIPRUEQ%26tag%3Dbanholzerme-20%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3DB003TKSD8E</URL>
          </ItemLink>
          <ItemLink>
            <Description>Tell A Friend</Description>
            <URL>http://www.amazon.de/gp/pdp/taf/B003TKSD8E%3FSubscriptionId%3DAKIAI6NFQHK2DQIPRUEQ%26tag%3Dbanholzerme-20%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3DB003TKSD8E</URL>
          </ItemLink>
          <ItemLink>
            <Description>All Customer Reviews</Description>
            <URL>http://www.amazon.de/review/product/B003TKSD8E%3FSubscriptionId%3DAKIAI6NFQHK2DQIPRUEQ%26tag%3Dbanholzerme-20%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3DB003TKSD8E</URL>
          </ItemLink>
          <ItemLink>
            <Description>All Offers</Description>
            <URL>http://www.amazon.de/gp/offer-listing/B003TKSD8E%3FSubscriptionId%3DAKIAI6NFQHK2DQIPRUEQ%26tag%3Dbanholzerme-20%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3DB003TKSD8E</URL>
          </ItemLink>
        </ItemLinks>
        <ItemAttributes>
          <Manufacturer>Apple Computer</Manufacturer>
          <ProductGroup>CE</ProductGroup>
          <Title>Apple iPhone 4 32GB schwarz</Title>/ItemAttributes>
        </Item>
      </Items>
    </ItemLookupResponse>

Can someone please explain me why I don't get any price-information?

Thank you very much

回答1:

To get prices for an item you need to include a ResponseGroup parameter of Offers or OfferFull and a MerchantId parameter of All:

$params = array(
    'AWSAccessKeyId' => self::API_KEY,
    'AssociateTag' => self::API_ASSOCIATE_TAG,
    'Version' => "2010-11-01",
    'Operation' => "ItemLookup",
    'Service' => "AWSECommerceService",
    'Condition' => "All",
    'IdType' => 'ASIN',
    'ResponseGroup' => 'Offers',                <- important
    'MerchantId' => 'All',                      <- important
    'ItemId' => $artNr);

If you don't include the MerchantId of All you will only get offer listings for Amazon (the default MerchantId). This will return the offer listings and your response will include something like the following:

<Items>
    ...
    <Item>
        ...
        <Offers>
            ...
            <Offer>
                ...
                <OfferListing>
                    <Price>
                        <Amount>1350</Amount>
                        <CurrencyCode>USD</CurrencyCode>
                        <FormattedPrice>$13.50</FormattedPrice>
                    </Price>
                    ...
                </OfferListing>
                ...
            </Offer>
       ...

See the documentation for the Offers Response Group for more information. Also see the Response Group request parameter description for the ItemLookup operation for more valid Response Groups.

回答2:

I suggest you use the OfferSummary response Group which will return something like this: ...

["Items"]=> object(stdClass)#72 (2) { 
    ... 
    ["Item"]=> object(stdClass)#75 (2) {
        ["ASIN"]=> string(10) "1405910232" 
        ["OfferSummary"]=> object(stdClass)#76 (6) { 
            ["LowestNewPrice"]=> object(stdClass)#77 (3) {  
                ["Amount"]=> int(247) 
                ["CurrencyCode"]=> string(3) "GBP" 
                ["FormattedPrice"]=> string(6) "£2.47" 
            } 
            ["LowestUsedPrice"]=> object(stdClass)#78 (3) {
                ["Amount"]=> int(297) 
                ["CurrencyCode"]=> string(3) "GBP" 
                ["FormattedPrice"]=> string(6) "£2.97" 
            }

...

回答3:

Use "medium" for "ResponseGroup" parameter, allowed values small, medium and large. small response will not have the price details.

http://docs.aws.amazon.com/AWSECommerceService/latest/DG/RG_Small.html

回答4:

Xarem, please, take a look at Product Advertising API (API Reference/Operations). You've requested ItemLookup operation and the price was not promissed for you. Use SellerListingLookup (or some other) operation to get available prices. This is quit understandable, because Amazon has a big pool of sellers and prices differ from one to another, so they can't provide prices for items, but for item-seller pairs.

回答5:

Had I enough rep I'd have commented on an earlier solution but alas I'm limited to providing a new answer...

So, if you pass a MerchantId value of All, you will see this in your response:

<MerchantId>Deprecated</MerchantId>

which indicates to me that perhaps you should not provide this parameter, counter to what the selected answer suggests.

More than that, I suspect there is something else going on. I'll probably pose a whole new question about this here, but I am submitting a request for a product with a valid ASIN, getting back True, requesting the response groups Offers, OfferFull, and OfferSummary, and I am not getting back any price information. Yet when I look at the very same product on amazom.com, I see see price information.

So something else could be wrong here.