Using LINQ to query XDocument, how to get specific values?

I'm trying to refactor the following - which works, but if I start to get more elements in the XML it'll get unmanageable :

HttpResponseMessage response = await httpClient.GetAsync("https://uri/products.xml");

string responseAsString = await response.Content.ReadAsStringAsync();

List<Product> productList = new List<Product>();

XDocument xdocument = XDocument.Parse(responseAsString);
var products = xdocument.Descendants().Where(p => p.Name.LocalName == "item");

foreach(var product in products)
{
    var thisProduct = new Product();
    foreach (XElement el in product.Nodes())
    {
        if(el.Name.LocalName == "id")
        {
            thisProduct.SKU = el.Value.Replace("-master", "");
        }
        if (el.Name.LocalName == "availability")
        {
            thisProduct.Availability = el.Value == "in stock";
        }
    }
    productList.Add(thisProduct);
}

Given the following XML URL

<rss xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
    xmlns="http://base.google.com/ns/1.0" version="0">
    <channel>
        <title>Product Feed</title>
        <link></link>
        <description>Products</description>
        <item>
            <availability>in stock</availability>
            <id>01234-master</id>
            ...
        </item>
        <item>
            <availability>in stock</availability>
            <id>abcde-master</id>
            ...
        </item>
    </channel>
</rss>

Ideally I'd like to remove the loops and if statements and have a LINQ query that returns only the fields I need (id, availability etc..) from the XML in a nice clean way and populate a simple class with this data.

Can anyone help?

Solution

Sometimes you have to be happy for the code you have written. Sometimes there is no "smarter" way to write it... You can only write it a little "better":

List<Product> productList = new List<Product>();

XDocument xdocument = XDocument.Parse(responseAsString);

XNamespace ns = "http://base.google.com/ns/1.0";

var products = from x in xdocument.Elements(ns + "rss")
               from y in x.Elements(ns + "channel")
               from z in y.Elements(ns + "item")
               select z;

foreach (var product in products)
{
    var prod = new Product();
    productList.Add(prod);

    foreach (XElement el in product.Elements())
    {
        if (el.Name == ns + "id")
        {
            prod.SKU = el.Value.Replace("-master", string.Empty);
        }
        else if (el.Name == ns + "availability")
        {
            prod.Availability = el.Value == "in stock";
        }
    }
}

Notes:

The Descendants() is morally wrong. There is a fixed position where the item will be, /rss/channel/item, and you know it perfectly well. It isn't //item. Because tomorrow there could be a rss/foo/item that today doesn't exist. You try to write your code so that it is forward compatible with additional informations that could be added to the xml.
I do hate xml namespaces... And there are xml with multiple nested namespaces. How much I hate those. But someone more intelligent than me decided that they exist. I accept it. I code using them. In LINQ-to-XML it is quite easy. There is a XNamespace that even has an overloaded + operator.

Note that if you are a micro-optimizer (I try not to be, but I have to admit, but my hands are itching a little), you can pre-calculate the various ns + "xxx" that are used inside the for cycle, because it isn't clear from here, but they are all rebuilt every cycle. An how a XName is built inside... oh... that is a fascinating thing, trust me.
```
private static readonly XNamespace googleNs = "http://base.google.com/ns/1.0";
private static readonly XName idName = googleNs + "id";
private static readonly XName availabilityName = googleNs + "availability";
```
and then
```
if (el.Name == idName)
{
    prod.SKU = el.Value.Replace("-master", string.Empty);
}
else if (el.Name == availabilityName)
{
    prod.Availability = el.Value == "in stock";
}
```