c# MVC XML Record Value

Question

I have an xml file:

<profiles>
  <profile username="user4" fullname="Full Name" />
 </profiles>

I am trying to retrive the value of the fullname, here is what I tried:

public List<string> GetFullName(string username)
{
    List<Profile> list = null;
    try
    {
        list = (from t in ProfileList
                where t.UserName == username
                select t).FirstOrDefault();
    }
    catch { }
    List<string> userFullName = new List<string>();
    if (list != null)
    {
        foreach (Profile t in list)
        {
            userFullName.Find(t.FullName);
        }
    }
    return userFullName;
}

FirstOrDefault gives an error!
Thanks in advance.

Dude, are you aware you have global variables in your code? Also, like the compiler, we can't infer the type of ProfileList. — linkerro
– linkerro, Commented Feb 23, 2012 at 22:26
FirstOrDefault gives an error Is that all? What is ProfileList? what error do you exactly get ? — L.B
– L.B, Commented Feb 23, 2012 at 22:28
@linkerro Actually the ProfileList type can be inferred by us. It should be IEnumerable<T> where T has a properties UserName and FullName. )) — Oybek
– Oybek, Commented Feb 28, 2012 at 7:41

Erik Dietrich · Accepted Answer · 2012-02-23 22:48:32Z

FirstOrDefault() is an extension method, which means that it's basically similar in concept to doing something like

var myList = new List<int>() { };
int myValue = StaticUtilsClass.FirstOrDefault(myList);

Now, if you look at FirstOrDefault documentation, notice that it throws a null argument exception when you pass in a null parameter.

What this means is that

List<int> myList = null;
myList.FirstOrDefault();

will throw an exception.

So, anytime you call x.FirstOrDefault(), and encounter a problem (i.e. an "error") the first thing to check is whether x, in this case, your query, is returning null.

From there, I would take a look at the fact that FirstOrDefault() is going to return a single entity, but you're setting it equal to a List<Profile>. Unless your ProfileList is an enumeration of List<Profile>, that's going to be a problem as well.

That should get you started anyway. Beyond that, it'd be helpful to know what ProfileList is and where it's declared.

Oybek · Accepted Answer · 2012-02-23 22:40:15Z

1

I'd rather rewrite your code like this

    public String GetFullName(string username)
    {
        var targetObject = (from t in ProfileList
                    where t.UserName == username
                    select t).FirstOrDefault();

        if (targetObject != null) return targetObject.FullName;
        throw new Exception("Target user is not found");
    }

answered Feb 23, 2012 at 22:40

Oybek

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