传递给控制器​​时，具有复杂类型的视图模型为null

Question

I am trying to pass a view model with complex types to my controller. I have researched everything I can top to bottom over this subject and I am still confused.

The Problem:

When I click my submit button, the view model is passed in but the List of MacroInfo property is null.

UpdateIndexViewModel

public class UpdateIndexViewModel
{
    //This view model will become larger later
    public List<MacroInfo> MacrosToUpdate { get; set; }
}

MacroInfo

public class MacroInfo
{
    public bool IsSelected { get; set; }
    public string FullPath { get; set; }
    public string Id { get; set; }
    public DateTime CreatedAt { get; set; }
}   

Controller Action

[HttpPost]
public ActionResult Submit(UpdateIndexViewModel updateIndexViewModel)
{
    //updateIndexViewModel.MacrosToUpdate is null ??
}

Index View

@model EplanInterface.Core.ViewModels.UpdateIndexViewModel

@using (Html.BeginForm("Submit", "Update", FormMethod.Post))
{
    <table style="width:100%" , class="table-bordered">
        <thead>
            <tr>
                <th>#</th>
                <th>Macro Path</th>
                <th>Created At</th>
                <th>Update</th>
            </tr>
        </thead>
        @for (int i = 1; i < Model.MacrosToUpdate.Count; i++)
        {
            <tr>
                <td>@Html.TextBoxFor(m =>Model.MacrosToUpdate[i].FullPath)</td>
                <td>@Html.TextBoxFor(m => Model.MacrosToUpdate[i].CreatedAt)</td>
                <td>@Html.CheckBoxFor(b => Model.MacrosToUpdate[i].IsSelected)</td>
            </tr>
        }
    </table>
    <input type="submit" class="btn btn-primary" value="Submit"/>
}

What I have tried

I tried changing the controller actions property being passed in to List<MacroInfo> macrosToUpdate , but when doing this the property is still null.

Chrome network inspection

Final Remarks

I am not sure if I need to be using an AJAX post to do this, or if my variable names just are not formatted correctly. I am pretty sure it is a binding issue I am not understanding.

If anyone could point me in the right direction I would really appreciate it.

Answer 1

This part of your template is bit wrong.

@for (int i = 1; i < Model.MacrosToUpdate.Count; i++)
{
    <tr>
        <td>@Html.TextBoxFor(m =>Model.MacrosToUpdate[i].FullPath)</td>
        <td>@Html.TextBoxFor(m => Model.MacrosToUpdate[i].CreatedAt)</td>
        <td>@Html.CheckBoxFor(b => Model.MacrosToUpdate[i].IsSelected)</td>
    </tr>
}

Please change with following and try again.

@for (int i = 0; i < Model.MacrosToUpdate.Count; 
{
        <tr>
            <td>@i</td>
            <td>@Html.TextBoxFor(m => m.MacrosToUpdate[i].FullPath)</td>
            <td>@Html.TextBoxFor(m => m.MacrosToUpdate[i].CreatedAt)</td>
            <td>@Html.CheckBoxFor(b => b.MacrosToUpdate[i].IsSelected)</td>
        </tr>
 }

First you were starting the loop with 1, which was the root cause. Model binder wasn't able to bind the list properly due to missing zeroth index.