asp.net core error on int null

Question

I want to be able to show data if an integer is not null. However, if is null I get error

@if (item.PTWSubsequent.PTWNoS != 0)
   {
     <div class="col-md-1">
       <a class="form-control text-center btn-link" asp-page="/PTW/IsolationCertificate" asp-route-ptwid="@item.PTWId" asp-route-ptwsid="@item.PTWSId">@Html.DisplayFor(model => item..PTWNoS)</a>
     </div>
   }

and code behind

PTWContentList = await _context.PTWContents.Include(s => s.PTWMain).Include(s => s.PTWSubsequent).Where(s => s.PTWMain.OrgID == orgid).ToListAsync();

I get the error that PTWNoS is null which I know is null. I just want to not show the div if is null

Sachin Singh · Answer

it means PTWSubsequent will be null @ if (item.PTWSubsequent!=null && item.PTWSubsequent.PTWNoS != 0) { class = "col-md-1" > class = "form-control text-center btn-link" asp-page= "/PTW/IsolationCertificate" asp-route-ptwid= "@item.PTWId" asp-route-ptwsid= "@item.PTWSId" >@Html.DisplayFor(model => item..PTWNoS) } you gave plural names so I thought so. like it's a list of integers.

Sachin Singh · Answer

it's like we are trying to fetch a value from an empty list, so the compiler doesn't understand this and throws error.

Sachin Singh · Answer

sir, how a List can be 0? its count can be 0, not the list itself. @ if (item.PTWSubsequent.PTWNoS.Count()>0) { class = "col-md-1" > class = "form-control text-center btn-link" asp-page= "/PTW/IsolationCertificate" asp-route-ptwid= "@item.PTWId" asp-route-ptwsid= "@item.PTWSId" >@Html.DisplayFor(model => item..PTWNoS) }

Marius Vasile · Answer

Now is working, thank you Sachin. So both the model and int to be checked not null, just the value is not enough

Marius Vasile · Answer

Is not the list, is a value, an integer