name property of the checkBox is throwing error the delegate type could not be inferred.

Question

I have the following Model class:

Public partial class EmployeeInfo

{

public int EmployeeInfoId { get; set; }

public string LastName { get; set; } = null!;

public string EmailAddress { get; set; } = null!;

public virtual Reassignment? Reassignment { get; set; }

}

public partial class Reassignment

{

public int ReassignmentId { get; set; }

public int EmployeeInfoId { get; set; }

public virtual EmployeeInfo EmployeeInfo { get; set; } = null!;

public virtual ICollection<ReassignmentSectionJoin> ReassignmentSectionJoins { get; } = new List<ReassignmentSectionJoin>();

}

public partial class ReassignmentSectionLookup

{

public int ReassignmentSectionLookupId { get; set; }

public string Category { get; set; } = null!;

public string Section { get; set; } = null!;

public virtual ICollection<ReassignmentSectionJoin> ReassignmentSectionJoins { get; } = new List<ReassignmentSectionJoin>();

}

public partial class ReassignmentSectionJoin

{

public int ReassignmentSectionJoinId { get; set; }

public int ReassignmentId { get; set; }

public int ReassignmentSectionLookupId { get; set; }

public virtual Reassignment Reassignment { get; set; } = null!;

public virtual ReassignmentSectionLookup ReassignmentSectionLookup { get; set; } = null!;

}

This is what I have in my controller class:

public async Task<IActionResult> Index()

{

       var ITSections= new List<ReassignmentSectionLookup>();

        ITSections= await _employeeService.GetITSections();

}

ViewData["ITSections"] = ITSections.Select(x => new SelectListItem

        {

            Value = x.ReassignmentSectionLookupId.ToString(),

            Text = x.Section

        }).ToList();

public async Task<List<ReassignmentSectionLookup>> GetITSections()

    {

        return await _ackContext.ReassignmentSectionLookups.Where(s => s.Category == "IT").ToListAsync(); ;

    }

My razor view looks like this:

<div>

                        <br /><b>ACR IT</b>  <br /><br />

                        @{

                            var ITSections = ViewData["ITSections"] as List<SelectListItem>;

                            if (ITSections != null && ITSections.Any())

                            {

                                foreach (var item in ITSections)

                                {

                                    <input type="checkbox" name"@Model.Reassignment.ReassignmentSectionJoins.ToList()[count].ReassignmentSectionLookup" value="@item.Value" @(Html.Raw(item.Selected ? "checked=\"checked\"" : "")) /> @item.Text  <br />

                                }

                            }

                        }

                    </div>

I am getting an error at this line

name="@Model.Reassignment.ReassignmentSectionJoins.ToList()[count].ReassignmentSectionLookup"

The error is:

The delegate type could not be inferred.

The issue is when I do HTTPPost. I dont see any value in the employeeInfo, but I do see value in selectedItems:

any help will be appreciated.

Answer 1

Hi @Anjali Agarwal

So now the question is the NullReferenceException error, right?

For this issue, since this the create page, in the Get action method, you didn't return a EmployeeInfo model to the Create razor view, so, the page model (EmployeeInfo @Model) is null, and the related navigation properties such as: Reassignment, ReassignmentSectionJoins, and ReassignmentSectionLookup also will be null. So, when using the @model to bind the checkbox element it will show the NullReferenceException error.

To solve this error, in the Get action method, you can create a new EmployeeInfo entity and return it to the razor view, or you can bind the checkbox like this:

        var ITSections = ViewData["ITSections"] as List<SelectListItem>;
        if (ITSections != null && ITSections.Any())
        {
            foreach (var item in ITSections)
            { 
                <input type="checkbox" name="Reassignment.ReassignmentSectionJoins[0].ReassignmentSectionLookup.SelectedSection" 
                value="@item.Value" @(Html.Raw(item.Selected ? "checked=\"checked\"" : "")) /> @item.Text  <br />
                            
            }
        }

In the ReassignmentSectionLookup class, add a SelectedSection property to store the checkbox checked value.

    public partial class ReassignmentSectionLookup
    {
        public int ReassignmentSectionLookupId { get; set; }

        public string Category { get; set; } = null!;

        public string Section { get; set; } = null!;
        //add this property to store the checkbox selected value 
        [NotMapped]
        public string[] SelectedSection { get; set; }

        public virtual ICollection<ReassignmentSectionJoin> ReassignmentSectionJoins { get; } = new List<ReassignmentSectionJoin>();
    }

The result as below:

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