CODEWITHSUNDEEP
c#asp.net-mvccollections
Prd
Prd

Reputation: 247

Check if collection is empty or not

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.

Upvotes: 15

Views: 69794

Answers (6)

Ken Vickers
Ken Vickers

Reputation: 1

This worked for me in Dot Net Core but only for IEnumerable of Models not Entities (I got a bit of help from AutoMapper)

Cast it as a List then check the Capacity

IEnumerable<vwPOD_Master> podMasters = _podRepository.GetNewPods(PartNumber);

IEnumerable<NewPODsDTO> podList = Mapper.Map<IEnumerable<NewPODsDTO>>(podMasters);

if (((List<NewPODsDTO>)podList).Capacity == 0) {
    return NotFound(); 
}

Upvotes: 0

Roadie57
Roadie57

Reputation: 324

How about checking the array length

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

Upvotes: 0

mantal
mantal

Reputation: 1209

You can use the method Any to know if a collection as any element.

if (devices.Any())
{
   //devices is not empty
}

Upvotes: 16

ChrisWay
ChrisWay

Reputation: 1167

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();
        }
    }
}

Upvotes: 10

thecoop
thecoop

Reputation: 46098

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.

Upvotes: 1

Manaf Abu.Rous
Manaf Abu.Rous

Reputation: 2417

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
}

Upvotes: 18

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