Question

I’m trying to figure how to properly represent values, process selected and later on edit form display checked items as checked and other possible values as nonchecked.

I already try something but I’m not sure am I on the right track. With using these solution edit form only display checked item, and not showing other non checked.

If you have better solution please share, cause I’m trying to figure how these work.

Here it is: Assume there is User which may belong to one or many Roles. So I would represent these trough two viewmodels, UserViewModel and RoleViewModel

**UserViewModel.cs**

public int id {get; set;}
public string username {get; set;}

public UserViewModel()
{
   Roles = new List<RoleViewModel>();
}

public void SendToDomain(User user, ISession nhibSession)
{
   if(user.Roles != null)
   {
      user.Roles.Clear();//Clear previous selected items
      foreach(Role role in Roles)
      {
        if(role.IsInRole)
          user.Role.Add(nhibSession.Load<Role>(user.RoleId)); 
      }
   }
}

**RoleViewModel**
public bool IsInRole {get; set;}

[HiddenInput(displayValue = false)]
public int RoleId {get; set;}

[HiddenInput(displayValue = true)]
public string RoleName {get; set;}

And inside EditorTemplates I have RoleViewModel.cs

@model Models.RoleViewModel

@Html.CheckBoxFor(m=>m.IsInRole)
@Html.HiddenFor(m=>m.RoleId)
@Html.LabelFor(m=>m.IsInRole, Model.RoleName)

And finally inside Create view I display these like these
@model Models.UserViewModel

<div> User roles </div> <div> @Html.EditorFor(m => m.Roles) </div>

Answer 1

Here’s how to do it:

UserViewModel

public int id {get; set;}
public string username {get; set;}
public int[] RoleIdsSelected { get; set; } 

FormView

You need to loop on all Roles that exists in your application. Then, create a checkbox that will be linked to your UserViewModel.RolesIdsSelected and compare the values to the current role.RoleId that is printed. If there’s a match, there will be a check.

@model UserViewModel

@{
    foreach (var role in (IEnumerable<Role>)ViewBag.AllRoles)
    {
        <label>
            @Html.CheckBoxFor(x => x.RoleIdsSelected, role.RoleId)
            @role.RoleName
        </label>
    }
}

CheckboxExtensions

public static class InputExtensions
{
    public static MvcHtmlString CheckBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, object value)
    {
        return htmlHelper.CheckBoxFor<TModel, TProperty>(expression, value, null);
    }

    public static MvcHtmlString CheckBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, object value, object htmlAttributes)
    {
        return htmlHelper.CheckBoxFor<TModel, TProperty>(expression, value, HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes));
    }

    public static MvcHtmlString CheckBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, object value, IDictionary<string, object> htmlAttributes)
    {
        ModelMetadata modelMetadata = ModelMetadata.FromLambdaExpression<TModel, TProperty>(expression, htmlHelper.ViewData);
        return CheckBoxHelper<TModel, TProperty>(htmlHelper, modelMetadata, modelMetadata.Model, ExpressionHelper.GetExpressionText(expression), value, htmlAttributes);
    }

    private static MvcHtmlString CheckBoxHelper<TModel, TProperty>(HtmlHelper htmlHelper, ModelMetadata metadata, object model, string name, object value, IDictionary<string, object> htmlAttributes)
    {
        if (value == null)
        {
            throw new ArgumentNullException("value");
        }

        RouteValueDictionary routeValueDictionary = htmlAttributes != null ? new RouteValueDictionary(htmlAttributes) : new RouteValueDictionary();

        string fullHtmlFieldName = htmlHelper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(name);

        if (string.IsNullOrEmpty(fullHtmlFieldName))
        {
            throw new ArgumentException("Le nom du control doit être fourni", "name");
        }

        TagBuilder tagBuilder = new TagBuilder("input");

        tagBuilder.MergeAttributes<string, object>(htmlAttributes);
        tagBuilder.MergeAttribute("type", HtmlHelper.GetInputTypeString(InputType.CheckBox));
        tagBuilder.MergeAttribute("name", fullHtmlFieldName, true);

        string text = Convert.ToString(value, CultureInfo.CurrentCulture);

        tagBuilder.MergeAttribute("value", text);

        if (metadata.Model != null)
        {
            foreach (var item in metadata.Model as System.Collections.IEnumerable)
            {
                if (Convert.ToString(item, CultureInfo.CurrentCulture).Equals(text))
                {
                    tagBuilder.Attributes.Add("checked", "checked");
                    break;
                }
            }
        }

        return MvcHtmlString.Create(tagBuilder.ToString(TagRenderMode.SelfClosing));
    }
}

When you will post your data, you will have in the UserViewModel.RolesIdsSelected the ids that have been checked by the user. Then, save the change!