how to pass list of object from view to controller in asp.net mvc

Question

first i create list of models in [HttpGet] action and return to view.

public ActionResult Setting()
{
        var model = db.Settings.ToList();
        return View(model);
}

them in view get list in view and show good. but after edit the value of setting i want to pass list of object from view to controller don't work this.

@model List<TajerWebsite.Models.Setting>

<!-- Main content -->
<section class="content">
    <div class="container-fluid">
        <div class="row">
            <!-- left column -->
            <div class="col-md-6">
                <!-- general form elements -->
                <div class="card card-primary">
                    <div class="card-header">
                        <h3 class="card-title">تنظیمات</h3>
                    </div>
                    <!-- /.card-header -->
                    <!-- form start -->
                    @using (Html.BeginForm("Setting","Admin", new { FormMethod.Post }))
                    {

                        @Html.AntiForgeryToken()
                        foreach (var item in Model)
                        {
                            <div class="card-body">
                                <div class="form-group">
                                    @Html.HiddenFor(model => item.Id)
                                    <label for="exampleInputPassword1">@item.Name</label>
                                    @Html.EditorFor(model => item.Value, new { htmlAttributes = new { @class = "form-control"} })
                                    @Html.ValidationMessageFor(model => item.Value, "", new { @class = "text-danger" })
                                </div>

                            </div>
                        }

                        <!-- /.card-body -->

                        <div class="card-footer">
                            <button type="submit" class="btn btn-primary">ذخیره</button>

                        </div>
                    }
                </div>
            </div>
        </div>
    </div>
</section>

and action is :

[HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Setting(IEnumerable<Models.Setting> settings)
    {
        db.Entry(settings);
        db.SaveChanges();
        return View(settings);
    }

but settings is null!

Answer 1

Few things going on here. The model needs all fields to be used one way or another to be recognized. Here is a sample solution

public class Song
{
    public string Name { get; set; }
    public int Id { get; set; }
    public string Artist { get; set; }
    public Genre genre { get; set; }

    public int length { get; set; }
    
}

public class Playlist
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public List<Song> Songs { get; set;}
}

public class MusicViewModel
{
    public int Id { get; set; }
    public Playlist Playlist { get; set; }
    public string Title { get; set; }
}

and then in the View, notice how I use Model, not model, this matters. As well as Model.list[i], rather than element at. Hope this helps.

@using (Html.BeginForm("Create", "Music", FormMethod.Post))
{
@Html.AntiForgeryToken()

<table class="table">
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.Title)
        </th>
        <th></th>
    </tr>

        <tr>
            <td>
                @Html.EditorFor(model => Model.Title)
            </td>
            <td>
                @Html.EditorFor(model => Model.Id)
            </td>
        </tr>
</table>

<table class="table">
    <tr>
        <th>
            Playlist Name
        </th>
        <th>
            Description
        </th>
        <th>
            Id
        </th>
        <th>
            Songs
        </th>
    </tr>
    <tr>
        <td>
            @Html.EditorFor(model => Model.Playlist.Name)
        </td>
        <td>
            @Html.EditorFor(model => Model.Playlist.Description)
        </td>
        <td>
            @Html.EditorFor(model => Model.Playlist.Id)
        </td>
        <td>
            @*@Html.HiddenFor(model => Model.Playlist.Songs)*@
        </td>
    </tr>


</table>


<table class="table">
    <tr>
        <th>
            Name
        </th>
        <th>
            Artist
        </th>
        <th>
            Genre
        </th>
        <th>
            Length
        </th>
        <th></th>
    </tr>

    @for(int i=0; i< Model.Playlist.Songs.Count; i++)
    {
        <tr>
            <td>
                @Html.EditorFor(model => Model.Playlist.Songs[i].Name)
            </td>
            <td>
                @Html.EditorFor(model => Model.Playlist.Songs[i].Artist)
            </td>
            <td>
                @Html.EditorFor(model => Model.Playlist.Songs[i].genre)
            </td>
            <td>
                @Html.EditorFor(model => Model.Playlist.Songs[i].length)
            </td>
            <td>
                @Html.EditorFor(model => Model.Playlist.Songs[i].Id)
            </td>
        </tr>
    }

</table>
<p>
    <input type="submit" value="Create" class="btn btn-default" />
</p>

}

Answer 2

You can't use @foreach loop in the view in order to pass list of object back to the controller, because that would generate input elements with same IDs and Names.

Instead, use standard for loop:

for(int i = 0; i < Model.Count; i++)
{
    <div class="card-body">
        <div class="form-group">
            @Html.HiddenFor(m => m[i].Id)
            <label for="exampleInputPassword1">@Model[i].Name</label>
            @Html.EditorFor(m => m[i].Value, 
                new { htmlAttributes = new { @class = "form-control"} })
            @Html.ValidationMessageFor(m => m[i].Value, 
                new { @class = "text-danger" })
        </div>
    </div>
}