Question

I have this LINQ query:

XNamespace ns = NAMESPACE;

var items = (from c in doc.Descendants(ns +"Item")
select new Item
{
     Title = c.Element(ns + "ItemAttributes").Element(ns + "Title").Value,
     MFR = c.Element(ns + "ItemAttributes").Element(ns + "Manufacturer").Value,
     Offer = c.Element(ns + "Offers").Element(ns + "TotalOffers").Value,
     Amazon = c.Element(ns + "Offer").Element(ns + "Merchant").Elements(ns + "MerchantId"),
     LowPrice = Convert.ToDouble(c.Element(ns + "FormattedPrice").Value),
     SalesRank = Convert.ToInt32(c.Element(ns +"SalesRank").Value),
     ASIN = c.Element(ns + "ASIN").Value
}).ToList<Item>();

It works great expect for when a node is not present. For example it my not have a MFR or a sales rank. How can I make it so if it does not have the node in question, it gives me a default value or at the very doesn’t make me try catch my whole query for one item.

Answer 1

As far as I’m aware LINQ to XML doesn’t support this. However I ran into this same mess in a project I was working on and created this extension for XElement to allow it. Maybe it could work for you:

public static XElement ElementOrDummy(this XElement parentElement, 
                                      XName name, 
                                      bool ignoreCase)
{
    XElement existingElement = null;

    if (ignoreCase)
    {
        string sName = name.LocalName.ToLower();

        foreach (var child in parentElement.Elements())
        {
            if (child.Name.LocalName.ToLower() == sName)
            {
                existingElement = child;
                break;
            }
        }
    }
    else
        existingElement = parentElement.Element(name);

    if (existingElement == null)
        existingElement = new XElement(name, string.Empty);

    return existingElement;

}

Basically it just checks to see if the element exists and if it doesn’t it returns one with the same name and an empty value.