var person = People.SingleOrDefault(p => p.Name == parameter);
SelectedPerson = person ?? DefaultPerson
Could this be written in one statement?
Measing can I provide the default element that SingleOrDefault returns?
I am looking for someting like this (the second argument is the default element I provide).
var person = People.SingleOrDefault(p => p.Name == parameter, DefaultPerson);
The solution should also work for value types (ints, doubles, enums, structs, ...).
You can use DefaultIfEmpty():
var person = People.Where(p => p.Name == parameter).DefaultIfEmpty(DefaultPerson).Single();
DefaultIfEmpty still returns IEnumerable so another First() is necessary. But yes, that's what I was looking for! Thx
You can define an extension:
public static T SingleOrDefault<T>
(this IEnumerable<T> list, T defaultValue)
where T : class
{
return list.SingleOrDefault() ?? defaultValue;
}
and then call it with:
var person = People.SingleOrDefault(p => p.Name == parameter, DefaultPerson);
It's a little obvious, but would this work for you?
var person = People.SingleOrDefault(p => p.Name == parameter) ?? DefaultPerson;
You can create an extension method, which give you an instance if nothing will be found:
public static class PersonExtensionMethod
{
public static T SingleOrInstance<T>(this IEnumerable<T> source, Func<T, bool> precate)
{
var person = source.SingleOrDefault(precate);
if (person == null)
return (T)Activator.CreateInstance(typeof(T));
return person;
}
}
and call it like this:
List<Person> persons = new List<Person> { new Person(), new Person(), new Person() };
var foundPerson = persons.SingleOrInstance<Person>(p => p.Name == "bla");
SelectedPerson = People.SingleOrDefault(p => p.Name == parameter)??DefaultPerson? it should work.ints?