Question

I have a variable length list of person models that I use @Html.EditorFor to generate a form for.

public class Person
{
    public string First { get; set; }
    public string Last { get; set; }
}

What would be the best way to validate that no person objects have the same first and last name?

Answer 1

The following is a minimal implementation of validating that no 2 items in a Person collection are the same:

public class NoDuplicatePersonsAttribute : ValidationAttribute
{
    public override bool IsValid(object value)
    {
        var people = value as IList<Person>;
        int count = people.Count();

        if (people == null) return true;

        for (int x = 0; x < count; x++)
        {
            for (int y = 0; y < count; y++)
            {
                if (x != y &&
                    people[x].FirstName == people[y].FirstName &&
                    people[x].LastName == people[y].LastName) 
                        return false;
            }
        }

        return true;
    }
}

public class IndexViewModel
{
    [NoDuplicatePersons]
    public IList<Person> People { get; set; }
}


public class Person
{
    public string FirstName{ get; set; }
    public string LastName { get; set; }
}