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Getting document reports from Amazon Seller Central SOAP services (C#)

Sunday, March 22nd, 2009

Developing against the Amazon API becomes a lot more straightforward with being able to get at the errors with your XML documents. Validating against the XSDs is only part of the solution, but even downloading reports can be tricky. Trouble is, the documentation from Amazon is a very closed & private sort of affair – sometimes out of date and sometimes very sparse. Perhaps they should think about a wiki :)

Getting at your reports consists of two parts, firstly – use the Document ID (long) you got from posting the XML in the first place.

public DocumentProcessingInfo DocumentStatus(long DocumentID)
    {
        //Setup the service interface, set the URL of the service
        //and add our credentials.
        merchantinterfacedime myAmazon =
            new merchantinterfacedime();
        myAmazon.Url = ConfigurationManager.AppSettings["URL"];
        myAmazon.Credentials =
            new NetworkCredential(
                ConfigurationManager.AppSettings["UserName"],
                ConfigurationManager.AppSettings["Password"]);
        //Setup our merchant details.
        Merchant myMerchant = new Merchant();
        myMerchant.merchantIdentifier =
            ConfigurationManager.AppSettings["MerchantIdentifier"];
        myMerchant.merchantName =
            ConfigurationManager.AppSettings["MerchantName"];
        //Send it all off to Amazon.
        DocumentProcessingInfo myStatus =
            myAmazon.getDocumentProcessingStatus(
            myMerchant, DocumentID);
        //Return the status of the document.
        return myStatus;
    }

This will give you the status of your upload, as well as whether it’s complete or not. It also gives you another document ID, which you can use to get at your much-needed reports.

public string GetDocument(string id) {
        StringBuilder report = new StringBuilder();
        merchantinterfacedime myAmazon =
            new merchantinterfacedime();
        myAmazon.Url = ConfigurationManager.AppSettings["URL"];
        myAmazon.Credentials =
            new NetworkCredential(
                ConfigurationManager.AppSettings["UserName"],
                ConfigurationManager.AppSettings["Password"]);
        //Setup our merchant details.
        Merchant myMerchant = new Merchant();
        myMerchant.merchantIdentifier =
            ConfigurationManager.AppSettings["MerchantIdentifier"];
        myMerchant.merchantName =
            ConfigurationManager.AppSettings["MerchantName"];
        ReferencedBinary incomingDoc = new ReferencedBinary();
        // the seven-digit string is the document ID number
        myAmazon.getDocument(myMerchant, id, out incomingDoc);
        IEnumerator enumer = myAmazon.ResponseSoapContext.Attachments.GetEnumerator();
        while (enumer.MoveNext())
        {
            // Print the document to standard out
            Attachment downloadedDoc = enumer.Current as Attachment;
            StreamReader r = new StreamReader(downloadedDoc.Stream);
            report.Append(r.ReadToEnd());
        }
        return report.ToString();
}

And tying it all together:

long amazonId = #######
string report = GetDocument(DocumentStatus(amazonId).processingReport.documentID);

Your report will be in XML, and give you any validation errors that might be preventing your feed from working properly, as well as some very helpful status on the number of items processed. How did you ever live without it?

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Code highlighting, and the magic of LINQ

Sunday, February 22nd, 2009

I’ve had a small block of code in my drafts folder for quite some time now, just looking for an excuse to publish it.  I’ve been using LINQ a lot in the past 6 months, and it’s one of the recent additions to the language that’s made me think twice before using PHP or Perl for my own projects (despite the existence of PHPLinq).

HIM: LINQ’s like pringles
ME: only makes sense after drugs?
HIM: once you pop you can’t stop

But I didn’t really want to write a full post on LINQ.  It seemed dull.  It’d been done before.  It’s old news.

So I picked up the WP-SynHighlight extension for WordPress.  Which gives some rather cool code-highlighting through GeSHi.

So here’s some highlighted stylised C# LINQ demonstrating how simple it is to combine LINQ to SQL with LINQ to XML data sources.

var answers = (from a in poll.Descendants("AnswerSet").Descendants("Answer")
join aCount in dbVotes
on a.Attribute("id").Value  equals aCount.AnswerId.ToString() into aJoined
from o in aJoined.DefaultIfEmpty()
select new {
id = a.Attribute("id").Value,
percentage = ((o == null ? 0 : o.VotesCount) / dbVotes.Sum(b => b.VotesCount.GetValueOrDefault())  * 100),
count = o == null ? 0 : o.VotesCount, text = a.Value
});

Now if only Microsoft would release LINQ to XSD out of preview.

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