c# Form Collection Values to List of Int

Question

I have a Form Collection in my C# MVC4 application. In index[0] of this collection there is a string that will always be formatted like "10=on&13=on&15=on"; the only difference being the number of #=on in the string.

I want to pull each of the numbers from this string and add them to a list of ints. What would be the simplest method of doing this? Is Regex required?

Answer 1

var nums = Regex.Matches(input, @"\d+").Cast<Match>().Select(m => m.Value)
          .ToList();

Answer 2

What would be the simplest method of doing this?

I would use a custom model binder:

public class MyModelBinder : IModelBinder
{
    public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        var request = controllerContext.RequestContext.HttpContext.Request.Params;
        var keys =
            from key in request.Keys.Cast<string>()
            where request[key] == "on"
            select key;
        var onValues = new List<int>();
        foreach (var key in keys)
        {
            int value;
            if (int.TryParse(key, out value))
            {
                onValues.Add(value);
            }
        }

        return onValues.ToArray();
    }
}

and then a controller action like that:

public ActionResult SomeAction([ModelBinder(typeof(MyModelBinder))]int[] values)
{
    return View();
}

Now you could simply send the following request to this controller action and the custom model binder will do the job:

/SomeAction?10=on&13=on&15=on

Is Regex required?

Nooooooooooooooooooooo.

Answer 3

The string in question looks like a query string so one approach would be to use System.Web.HttpUtility.ParseQueryString() to get a NameValueCollection from the string. Then enumerate the keys and parse them to get integers.

var collection = System.Web.HttpUtility.ParseQueryString("10=on&13=on&15=on");

foreach (var key in collection.Keys.Cast<string>())
{
    int i;
    if (int.TryParse(key, out i))
    {
        // add i to list of ints
    }
}