Check if collection is empty or not

Question

public ActionResult Create(FormCollection collection, FormCollection formValue)
    {
        try
        {
            Project project = new Project();

            TryUpdateModel(project, _updateableFields);

            var devices = collection["devices"];
            string[] arr1 = ((string)devices).Split(',');
            int[] arr2 = Array.ConvertAll(arr1, s => int.Parse(s));


                project.User = SessionVariables.AuthenticatedUser;
                var time = formValue["Date"];
                project.Date = time;
                project.SaveAndFlush();

                foreach (int i in arr2)
                {
                    Device d = Device.Find(i);
                    d.Projects.Add(project);
                    d.SaveAndFlush();
                }


            return RedirectToAction("Index");

        }
        catch (Exception e)
        {
            return View(e);
        }
    }

I want to wrap the foreach in a if statement which checks if

var devices = collection["devices"];

is empty or not. If its empty the for each should not be executed. For the record, collection["devices"] is a collection of checkbox values from a form.

I cant seem to get it to work, can someone help me?

Answer 1

You can use the Count field to check if the collection is empty or not

so you will end up with something like this :

if(devices.Count > 0)
{
   //foreach loop
}

Answer 2

How about checking array length

If (arr2.length > 0) {
                    foreach (int i in arr2)
                    {
                        Device d = Device.Find(i);
                        d.Projects.Add(project);
                        d.SaveAndFlush();
                    }
}

Answer 3

Your code, as it stands, won't work, as you say that collection["devices"] is a collection of checkbox values, and yet you're casting it to a string. Do you mean collection is the checkbox values? What is the exact type of collection?

Any object that implements ICollection or ICollection<T> can be checked whether it's empty or not by checking if the Count property is greater than zero.

Answer 4

You do not need to check if the collection is empty, if it is empty the code inside the ForEach will not be executed, see my example below.

using System;
using System.Collections.Generic;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            List<string> emptyList = new List<string>();

            foreach (string item in emptyList)
            {
                Console.WriteLine("This will not be printed");
            }

            List<string> list = new List<string>();

            list.Add("item 1");
            list.Add("item 2");

            foreach (string item in list)
            {
                Console.WriteLine(item);
            }

            Console.ReadLine();
        }
    }
}