Question

My code:

public string LocName(string locID)
    {
        var name = (from a in idc.Locations
                    where a.ID.ToString() == locID
                    select a.Name).Single();
        return name;   
    }

I need it to return the name of the Location that matches the ID as a string for a TextBlock. Instead it returns no elements, I have checked that the ID is correct so it should return at least one element.

I have also tried:

where a.ID == new Guid(locID)

as well as

.First()
.FirstOrDefault()

have tried returning the result as an element and databinding to that but still – no elements.

What is the error???

Answer 1

Must be a casing issue if the data is there, you should always use ToUpper() as that is optimised for string equality checks.

Also you should always use FirstOrDefault as Single will throw an exception if there are more than one matches and First will throw an exception if there are no matches. Try:

EDIT: I’ve also added Trim on the inputted value to sanitise the spaces. I’ve also added a null check on the locID parameter as that would blow up if it was passed is as null. Lastly, I added a ?? (coalesce) on the return statement just incase it is returning null and you’re performing other things on that string (such as Trim or ToLowerCase) as that would result in an exception.

public string LocName(string locID)
{
    if (locID == null) return string.Empty;

    var name = (from a in idc.Locations
                where a.ID.ToString().Trim().ToUpper() == locID.Trim().ToUpper()
                select a.Name).FirstOrDefault();

    return name ?? string.Empty;   
}