Finding an attribute of an element using XDocument

Question

I am trying to get a PurchaseDate from the following XML structure (receipt from an in-app purchase on Windows Phone):

<Receipt Version="1.0" CertificateId="..." xmlns="http://schemas.microsoft.com/windows/2012/store/receipt"> <ProductReceipt PurchasePrice="$0" PurchaseDate="2013-05-20T19:27:09.755Z" Id="..." AppId="..." ProductId="Unlock" ProductType="Consumable" PublisherUserId="..." PublisherDeviceId="..." MicrosoftProductId="..." /> <Signature xmlns="http://www.w3.org/2000/09/xmldsig#"> <SignedInfo> <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" /> <SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256" /> <Reference URI=""> <Transforms> <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature" /> </Transforms> <DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256" /> <DigestValue>...</DigestValue> </Reference> </SignedInfo> <SignatureValue>...</SignatureValue> </Signature> </Receipt> 

My code is as follows:

 XDocument doc = XDocument.Parse(receiptXml); string date = doc.Root.Element("ProductReceipt").Attribute("PurchaseData").Value; 

This leads to an increase in access error because doc.Root.Element("ProductReceipt") is null. Why is XDocument not getting a ProductReceipt element?

Answer 1

Just add the namespace to the LINQ to XML query. Since you have the default namespace declaration in the root directory node xmlns="http://schemas.microsoft.com/windows/2012/store/receipt" , you also need to include it in your request.

The following code shows an example:

 XDocument doc = XDocument.Parse(receiptXml); XNamespace xmlns = "http://schemas.microsoft.com/windows/2012/store/receipt"; string date = doc.Root .Element(xmlns + "ProductReceipt") .Attribute("PurchaseDate") .Value; Console.WriteLine(date); 

prints:

 2013-05-20T19:27:09.755Z 

There is also an agnostic namespace approach:

 string date = doc.Root .Elements() .First(node => node.Name.LocalName == "ProductReceipt") .Attribute("PurchaseDate") .Value;