Question

The following example illustrates how to set a default value for a LINQ to XML query when data is missing:

IEnumerable<Person> persons =
from e in x.Descendants("Person")
select new Person { 
    Name = e.Value,
    Age = (int?)e.Attribute("Age") ?? 21
};

But how do you handle when an attribute is missing altogether? For example what if the node has no parent node?

IEnumerable<Person> persons =
    from e in x.Descendants("Person")
    select new Person { 
        Name = e.Value,
        Age = (int?)e.Attribute("Age") ?? 21
        ParentAge = e.Parent.Attribute("Age")
    };

Answer 1

You handle it the hard way, usually with the ternary conditional operator:

IEnumerable<Person> persons =
    from e in x.Descendants("Person")
    select new Person { 
        Name = e.Value,
        Age = (int?) e.Attribute("Age") ?? 21,
        ParentAge = e.Parent != null ? (int) e.Parent.Attribute("Age") : 42
    };

To my knowledge, there is no shorter way to do that in C#.