Add Demo of select input and validation summary

Pages/Demos/SelectInput.cshtml

@@ -0,0 +1,26 @@
+@page
+@model DemoWeb.Pages.Demos.SelectInput
+@{
+    Layout = "Shared/_Layout";
+}
+
+<div asp-validation-summary="All">
+    <span>Please correct the following errors</span>
+</div>
+
+<fieldset>
+    <legend>Required Select input with validation summary.</legend>
+    <form method="post">
+        <div class="form-field">
+            <label asp-for="Animal"></label>
+            <select asp-for="Animal" asp-items="Model.Animals"></select>
+            <span asp-validation-for="Animal"></span>
+        </div>
+        <div class="form-field">
+            <label asp-for="AnotherRequiredField"></label>
+            <input asp-for="AnotherRequiredField" />
+            <span asp-validation-for="AnotherRequiredField"></span>
+        </div>
+        <input type="submit" value="Submit"/>
+    </form>
+</fieldset>

Pages/Demos/SelectInput.cshtml.cs

@@ -0,0 +1,25 @@
+using System.ComponentModel.DataAnnotations;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.AspNetCore.Mvc.Rendering;
+
+namespace DemoWeb.Pages.Demos;
+
+public class SelectInput : PageModel
+{
+    [BindProperty]
+    [Required]
+    public string? Animal { get; set; }
+
+    [BindProperty]
+    [Required]
+    public string? AnotherRequiredField { get; set; }
+
+    public IReadOnlyList<SelectListItem> Animals => new List<SelectListItem>
+    {
+        new("None", ""),
+        new("Dog", "Dog"),
+        new("Cat", "Cat"),
+        new("Fish", "Fish"),
+    };
+}

Pages/Index.cshtml

@@ -9,6 +9,7 @@
     <li><a asp-page="Demos/Checkboxes">Checkboxes and Radio Buttons</a></li>
     <li><a asp-page="Demos/SubmitButton">Submit Button</a></li>
     <li><a asp-page="Demos/RemovedInputs">Removed Inputs</a></li>
+    <li><a asp-page="Demos/SelectInput">Select Input and Validation Summary</a></li>
 </ul>
 
 @if (Model.StatusMessage != null) {