Add `ListBox()` and `ListBoxFor()` helper methods

- copy from legacy MVC
- get `ListBox[For]()` methods in correct places and working
 - also usual stuff: `var`, `[NotNull]`, remove `IDictionary<,>` overloads
 - `ListBoxHelper()` -> `GenerateListBox`
 - already had all the bits needed in `GenerateSelect()`
- special-case `null` or empty `name` in GenerateSelect()
 - ensure `ArgumentException` has correct parameter name
 - lower-level problem affected `CheckBox()` as well
- use `ListBox()` and `ListBoxFor()` in MVC sample
 - use `ListBox()` in an editor template

samples/MvcSample.Web/HomeController.cs

@@ -57,7 +57,7 @@ namespace MvcSample.Web
         public ActionResult Edit(User user)
         {
             ViewBag.Address = _addresses;
-            ViewBag.Age = _ages;
+            ViewBag.Ages = _ages;
             ViewBag.Gift = "the banana";
 
             return View("Create");

samples/MvcSample.Web/Models/User.cs

@@ -15,12 +15,19 @@
 // See the Apache 2 License for the specific language governing
 // permissions and limitations under the License.
 
+using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 
 namespace MvcSample.Web.Models
 {
     public class User
     {
+        public User()
+        {
+            OwnedAddresses = new List<string>();
+            ParentsAges = new List<int>();
+        }
+
         [Required]
         [MinLength(4)]
         public string Name { get; set; }
@@ -35,5 +42,9 @@ namespace MvcSample.Web.Models
         public string Profession { get; set; }
         public string About { get; set; }
         public string Log { get; set; }
+        public IEnumerable<string> OwnedAddresses { get; private set; }
+
+        // This does not bind correctly. Only gets highest value.
+        public List<int> ParentsAges { get; private set; }
     }
 }

samples/MvcSample.Web/MvcSample.Web.kproj

@@ -24,6 +24,7 @@
     <Content Include="Content\bootstrap.min.css" />
     <Content Include="Project.json" />
     <Content Include="Views\Home\Create.cshtml" />
+    <Content Include="Views\Home\EditorTemplates\IEnumerable`1.cshtml" />
     <Content Include="Views\Home\Test.cshtml" />
     <Content Include="Views\Home\ValidationSummary.cshtml" />
     <Content Include="Views\Link\Details.cshtml" />

samples/MvcSample.Web/Views/Home/Create.cshtml

@@ -2,7 +2,7 @@
 @using Microsoft.AspNet.Mvc.ModelBinding
 @model User
 @{
-    ViewBag.Title = (Model == null) ? "Create Page" : "Edit Page";
+    ViewBag.Title = (Model == null && ViewData.ModelState.Count == 0) ? "Create Page" : "Edit Page";
     if (ViewBag.Gift == null)
     {
         ViewBag.Gift = "nothing";
@@ -45,7 +45,7 @@
             <table>
                 <tr>
                     <td>
-                        <label class="control-label col-md-2">Model.Name</label>
+                        <label class="control-label col-md-2" for="Name">Model.Name</label>
                     </td>
                     <td>
                         @Html.TextBox("Name")
@@ -56,7 +56,7 @@
                 </tr>
                 <tr>
                     <td>
-                        <label class="control-label col-md-2">Model.Address</label>
+                        <label class="control-label col-md-2" for="Address">Model.Address</label>
                     </td>
                     <td>
                         @Html.DropDownList("Address", "Select an Address")
@@ -64,7 +64,7 @@
                 </tr>
                 <tr>
                     <td>
-                        <label class="control-label col-md-2">Model.Age</label>
+                        <label class="control-label col-md-2" for="Age">Model.Age</label>
                     </td>
                     <td>
                         @Html.DropDownListFor(model => model.Age, (IEnumerable<SelectListItem>)ViewBag.Ages, htmlAttributes: new { @class = "form-control" })
@@ -89,6 +89,22 @@
                         @Html.TextArea("About", "You can explain about your hobbies, work etc.", 5, 40, htmlAttributes: new { style = "font-weight:bold" })
                     </td>
                 </tr>
+                <tr>
+                    <td>
+                        <label class="control-label col-md-2" for="OwnedAddresses">Model.OwnedAddresses</label>
+                    </td>
+                    <td>
+                        @Html.Editor("OwnedAddresses")
+                    </td>
+                </tr>
+                <tr>
+                    <td>
+                        <label class="control-label col-md-2" for="ParentsAges">Model.ParentsAges</label>
+                    </td>
+                    <td>
+                        @Html.ListBoxFor(model => model.ParentsAges, (IEnumerable<SelectListItem>)ViewBag.Ages, htmlAttributes: new { @class = "form-control" })
+                    </td>
+                </tr>
                 <tr>
                     <td>
                         <input type="submit" value="Save" class="btn btn-default" style="margin-left: 10px" />

samples/MvcSample.Web/Views/Home/EditorTemplates/IEnumerable`1.cshtml

@@ -0,0 +1,4 @@
+@using System.Collections.Generic
+@model IEnumerable<string>
+
+@Html.ListBox(null, (IEnumerable<SelectListItem>)ViewBag.Address)

src/Microsoft.AspNet.Mvc.Core/Rendering/Html/HtmlHelper.cs

@@ -332,6 +332,12 @@ namespace Microsoft.AspNet.Mvc.Rendering
                             htmlAttributes);
         }
 
+        /// <inheritdoc />
+        public HtmlString ListBox(string name, IEnumerable<SelectListItem> selectList, object htmlAttributes)
+        {
+            return GenerateListBox(metadata: null, name: name, selectList: selectList, htmlAttributes: htmlAttributes);
+        }
+
         /// <inheritdoc />
         public virtual HtmlString Name(string name)
         {
@@ -866,6 +872,21 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return tagBuilder.ToHtmlString(TagRenderMode.Normal);
         }
 
+        protected HtmlString GenerateListBox(
+            ModelMetadata metadata,
+            string name,
+            IEnumerable<SelectListItem> selectList,
+            object htmlAttributes)
+        {
+            return GenerateSelect(
+                metadata,
+                optionLabel: null,
+                name: name,
+                selectList: selectList,
+                allowMultiple: true,
+                htmlAttributes: htmlAttributes);
+        }
+
         protected virtual HtmlString GeneratePassword(ModelMetadata metadata, string name, object value,
             object htmlAttributes)
         {
@@ -974,6 +995,14 @@ namespace Microsoft.AspNet.Mvc.Rendering
             // If we got a null selectList, try to use ViewData to get the list of items.
             if (selectList == null)
             {
+                if (string.IsNullOrEmpty(name))
+                {
+                    // Avoid ViewData.Eval() throwing an ArgumentException with a different parameter name. Note this
+                    // is an extreme case since users must pass a non-null selectList to use CheckBox() or ListBox()
+                    // in a template, where a null or empty name has meaning.
+                    throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, "name");
+                }
+
                 selectList = GetSelectListItems(name);
                 usedViewData = true;
             }

src/Microsoft.AspNet.Mvc.Core/Rendering/Html/HtmlHelperOfT.cs

@@ -170,6 +170,18 @@ namespace Microsoft.AspNet.Mvc.Rendering
             return GenerateLabel(metadata, ExpressionHelper.GetExpressionText(expression), labelText, htmlAttributes);
         }
 
+        /// <inheritdoc />
+        public HtmlString ListBoxFor<TProperty>(
+            [NotNull] Expression<Func<TModel, TProperty>> expression,
+            IEnumerable<SelectListItem> selectList,
+            object htmlAttributes)
+        {
+            var metadata = GetModelMetadata(expression);
+            var name = ExpressionHelper.GetExpressionText(expression);
+
+            return GenerateListBox(metadata, name, selectList, htmlAttributes);
+        }
+
         /// <inheritdoc />
         public HtmlString NameFor<TProperty>([NotNull] Expression<Func<TModel, TProperty>> expression)
         {

src/Microsoft.AspNet.Mvc.Core/Rendering/HtmlHelperSelectExtensions.cs

@@ -79,5 +79,26 @@ namespace Microsoft.AspNet.Mvc.Rendering
         {
             return htmlHelper.DropDownListFor(expression, selectList, optionLabel, htmlAttributes: null);
         }
+
+        public static HtmlString ListBox([NotNull] this IHtmlHelper htmlHelper, string name)
+        {
+            return htmlHelper.ListBox(name, selectList: null, htmlAttributes: null);
+        }
+
+        public static HtmlString ListBox(
+            [NotNull] this IHtmlHelper htmlHelper,
+            string name,
+            IEnumerable<SelectListItem> selectList)
+        {
+            return htmlHelper.ListBox(name, selectList, htmlAttributes: null);
+        }
+
+        public static HtmlString ListBoxFor<TModel, TProperty>(
+            [NotNull] this IHtmlHelper<TModel> htmlHelper,
+            [NotNull] Expression<Func<TModel, TProperty>> expression,
+            IEnumerable<SelectListItem> selectList)
+        {
+            return htmlHelper.ListBoxFor(expression, selectList, htmlAttributes: null);
+        }
     }
 }

src/Microsoft.AspNet.Mvc.Core/Rendering/IHtmlHelper.cs

@@ -294,6 +294,19 @@ namespace Microsoft.AspNet.Mvc.Rendering
         /// </returns>
         HtmlString Label(string expression, string labelText, object htmlAttributes);
 
+        /// <summary>
+        /// Returns a multi-selection HTML {select} element using the specified name of the form field,
+        /// list items, and HTML attributes.
+        /// </summary>
+        /// <param name="name">The name of the form field to return.</param>
+        /// <param name="selectList">A collection of <see href="SelectListItem"/> objects that are used to populate the
+        /// drop-down list.</param>
+        /// <param name="htmlAttributes">An object that contains the HTML attributes to set for the element.
+        /// Alternatively, an <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
+        /// </param>
+        /// <returns>An HTML {select} element with an {option} subelement for each item in the list.</returns>
+        HtmlString ListBox(string name, IEnumerable<SelectListItem> selectList, object htmlAttributes);
+
         /// <summary>
         /// Gets the full HTML field name for the given expression <paramref name="name"/>.
         /// </summary>

src/Microsoft.AspNet.Mvc.Core/Rendering/IHtmlHelperOfT.cs

@@ -175,6 +175,24 @@ namespace Microsoft.AspNet.Mvc.Rendering
                                     string labelText,
                                     object htmlAttributes);
 
+        /// <summary>
+        /// Returns a multi-selection HTML {select} element for the object that is represented by the specified
+        /// expression using the specified list items and HTML attributes.
+        /// </summary>
+        /// <typeparam name="TProperty">The type of the property.</typeparam>
+        /// <param name="expression">An expression that identifies the object that contains the properties to
+        /// display.</param>
+        /// <param name="selectList">A collection of <see href="SelectListItem"/> objects that are used to populate the
+        /// drop-down list.</param>
+        /// <param name="htmlAttributes">An object that contains the HTML attributes to set for the element.
+        /// Alternatively, an <see cref="IDictionary{string, object}"/> instance containing the HTML attributes.
+        /// </param>
+        /// <returns>An HTML {select} element with an {option} subelement for each item in the list.</returns>
+        HtmlString ListBoxFor<TProperty>(
+            [NotNull] Expression<Func<TModel, TProperty>> expression,
+            IEnumerable<SelectListItem> selectList,
+            object htmlAttributes);
+
         /// <summary>
         /// Gets the full HTML field name for the given <paramref name="expression"/>.
         /// </summary>