ASP.NET MVC/C# - Type casting to an array in a custom required validation attribute

Question

I'm attempting to create a custom required validation attribute which will be able to take in a 1d array of any size and verify that at least one element is not null/empty string. I'm having some trouble figuring out how to turn the incoming generic object into an array. Here's what I have so far:

public class RequiredArrayAttribute : RequiredAttribute
{
    public override bool IsValid(object value)
    {
        var valueType = value.GetType();

        if (!valueType.IsArray)
        {
            return false;
        }

        bool hasValue = false;

        foreach (var item in value)
        {
            /* if (item != null/empty)
             * {
             *    hasValue = true;
             * }
            */
        }

        return hasValue;
    }
}

While my specific use case in this instance will be dealing with string[], I'd like to keep the attribute as generic as possible for future use in other projects. Any ideas on how to proceed?

EDIT:

I basically need to do something like:

foreach (var item in (valueType[])value)
{
    // ...
}

But I'm not sure how/if it's possible to dynamically cast to an array like that.

What version of C# are you using? Can you use Linq and generics? ie. if you had a generic collection you could do something like .Where(x => x != null).Count() > 0 - of course that handles the null part rather than the empty string part :) — Jen
– Jen, Commented Aug 24, 2011 at 4:33
I'm using C# 4, so I have both LINQ and generics. I can represent my model data as a List<string> without a problem. However, the main problem still remains - how would I cast object value as a List<T>? — Major Productions
– Major Productions, Commented Aug 24, 2011 at 13:11
Does this help - something like the below - Assuming the object implements IList as opposed to IEnumerable: IList collection = (IList)myObject; — Jen
– Jen, Commented Aug 25, 2011 at 0:34

Community · Accepted Answer · 2017-05-23 12:12:06Z

0

i believe you need following: generic handeling of your loop: check answer below

C# Syntax - Example of a Lambda Expression - ForEach() over Generic List

Cast as T:

you can create separate class that will represent T

eg: public class Foo{ public string Boo{get;set;} }

and after you put it into List list = new List() etc:)

edited May 23, 2017 at 12:12

CommunityBot

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answered Aug 24, 2011 at 8:22

cpoDesign

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1 Comment

Major Productions Over a year ago

See my comment to Jen on my question.

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