Model is null in view on foreach - asp.net

Question

I have added a list to my view model but when I access it in a foreach loop in the view it throws:
NullReferenceException: Object reference not set to an instance of an object.
AspNetCore.Views_MyActivationCampaign_Campaign.ExecuteAsync() in Campaign.cshtml
+ foreach(var dp in Model.DpRestrictedList)
This is the list I have added:
public List<DpRestricted> DpRestrictedList { get; set; } = new List<DpRestricted>()
{
new DpRestricted(){DpId = 1, Name = "Post Restricted" },
new DpRestricted(){DpId = 2, Name = "Unrestricted" },
new DpRestricted(){DpId = 3, Name = "Customer Restricted" }
};
}
public class DpRestricted
{
public int DpId { get; set; }
public string Name { get; set; }
}
and I am trying to loop over it like this:
<div class="row">
<fieldset>
<legend>Delivery Methods</legend>
<div id="radio">
#*<input type="radio" id="new-method">
<label for="new-method">New Method</label>
<input type="radio" id="dm-101" checked="checked">
<label for="dm-101">DM_101</label>
<input type="radio" id="delivery-method-2">
<label for="delivery-method-2">Delivery Method 2</label>*#
#{
foreach(var dp in Model.DpRestrictedList)
{
#Html.RadioButtonFor(model => model.DeliveryPointRestrictionId, dp);
}
}
</div>
</fieldset>
</div>
Using statement and example:
#model WorkstreamX.Web.Core.ViewModels.ActivationCampaignViewModel
...
<div class="col-md-4">
<label for="headline">Campaign</label>
#Html.EditorFor(model => model.CampaignName, new { htmlAttributes = new { #class = "form-control" } })
#Html.ValidationMessageFor(model => model.CampaignName)
</div>
The above is the using statement in the view and an example of how it is already being used elsewhere in it. When I check it is not just the list that is null but the Model in the loop statement is also null. Is it a case of me needing to new up the view model in the controller at this point? That is what I am about to try I just wanted to state this question and maybe find out why this is happening. Any advice here greatly appreciated.
[edit] How I fixed this issue:
I added an argument to my view:
before return View();
after return View(new ActivationCampaignViewModel());
I still don't quite understand the why of this as I appeared to have a model before. I am assuming that because I didn't call the constructor the list wasn't constructed and made it all fall over.

Answer 1

Your code should be like the below one.
Public ActionResult GetEmployee()
{
var employee = GetEmployee();
return View(employee);
}
#model IEnumerable<Appname.ViewModel.Employee>
#{
foreach(var data in Model) {}
}

Answer 2

How I fixed this issue:
I added an argument to my view:
before return View();
after return View(new ActivationCampaignViewModel());
I still don't quite understand the why of this as I appeared to have a model before. I am assuming that because I didn't call the constructor the list wasn't constructed and made it all fall over.