如何使用带有验证的IEnumerable <t>的Html.CheckBox（列表）</t>

Question

我正在开设一个页面，用户需要填写一些信息，最后选择一个或多个带有复选框的客户。

客户列表是IEnumerable<Customer>，我将其传递给我的模型。如何使用.CheckBoxFor()创建复选框列表？

最后，我希望能够验证是否已选择至少1个复选框。

请求是保存用户输入信息的对象。

<% foreach (var customer in Model.Request.Customers) { %>
   <%= Html.CheckBoxFor(/* customer */) %>
<% } %>

有人能指出我正确的方向吗？或者我是不是错了？

Answer 1

您可以创建自定义html扩展类并重载CheckBoxFor方法，如下所示。该方法将metadata.Model计算为传递给它的值（如美国州）。您可以从ControllerAction中的FormCollection中获取复选框值：

public ActionResult Edit(FormCollection formCollection) 
{
    // Get the value(s)
    string checkBox = formCollection["State"];

    // perform validation
    ....
}

示例假定keyvaluepair通用列表

<% foreach (var element in UnitedStatesDictionary())
{ %>
<%= Html.CheckBoxFor(model => model.State, null, element.Key) %><%= element.Value  %><br />
<% } %>

HtmlExtensions.cs

using System;
using System.Linq;
using System.Linq.Expressions;
using System.Web.Mvc;
using System.Web.Routing;

    public static class HtmlExtensions
    {
        /// <summary>
        /// Checks the box for.
        /// </summary>
        /// <typeparam name="TModel">The type of the model.</typeparam>
        /// <typeparam name="TValue">The type of the value.</typeparam>
        /// <param name="html">The HTML.</param>
        /// <param name="expression">The expression.</param>
        /// <returns>Checkbox</returns>
        public static MvcHtmlString CheckBoxFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression)
        {
            return CheckBoxFor(html, expression, new RouteDirection());
        }


        /// <summary>
        /// Checks the box for.
        /// </summary>
        /// <typeparam name="TModel">The type of the model.</typeparam>
        /// <typeparam name="TValue">The type of the value.</typeparam>
        /// <param name="html">The HTML.</param>
        /// <param name="expression">The expression.</param>
        /// <param name="htmlAttributes">The HTML attributes.</param>
        /// <returns>Checkbox</returns>
        public static MvcHtmlString CheckBoxFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, object htmlAttributes)
        {

            return CheckBoxFor(html, expression, htmlAttributes, "");
        }

        /// <summary>
        /// Checks the box for.
        /// </summary>
        /// <typeparam name="TModel">The type of the model.</typeparam>
        /// <typeparam name="TValue">The type of the value.</typeparam>
        /// <param name="html">The HTML.</param>
        /// <param name="expression">The expression.</param>
        /// <param name="htmlAttributes">The HTML attributes.</param>
        /// <param name="checkedValue">The checked value.</param>
        /// <returns>Checkbox</returns>
        public static MvcHtmlString CheckBoxFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, object htmlAttributes, string checkedValue)
        {

            ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, html.ViewData);
            string htmlFieldName = ExpressionHelper.GetExpressionText(expression);

            TagBuilder tag = new TagBuilder("input");
            tag.Attributes.Add("type", "checkbox");
            tag.Attributes.Add("name", metadata.PropertyName);
            if (!string.IsNullOrEmpty(checkedValue))
            {
                tag.Attributes.Add("value", checkedValue);
            }
            else
            {
                tag.Attributes.Add("value", metadata.Model.ToString());
            }

            if (htmlAttributes != null)
            {
                tag.MergeAttributes(new RouteValueDictionary(htmlAttributes));
            }

            if (metadata.Model.ToString() == checkedValue)
            {
                tag.Attributes.Add("checked", "checked");
            }
            return MvcHtmlString.Create(tag.ToString(TagRenderMode.SelfClosing));
        }
    }

虽然我在这里，但这是我完成代码的美国名单：

/// <summary>
/// United States dictionary.
/// </summary>
/// <returns>List of United States</returns>
public static List<KeyValuePair<string, string>> UnitedStatesDictionary()
{
    var arrList = new List<KeyValuePair<string, string>>();
    arrList.Add(new KeyValuePair<string, string>("AL", "Alabama"));
    arrList.Add(new KeyValuePair<string, string>("AK", "Alaska"));
    arrList.Add(new KeyValuePair<string, string>("AZ", "Arizona" ));
    arrList.Add(new KeyValuePair<string, string>("AR", "Arkansas" ));
    arrList.Add(new KeyValuePair<string, string>("CA", "California" ));
    arrList.Add(new KeyValuePair<string, string>("CO", "Colorado" ));
    arrList.Add(new KeyValuePair<string, string>("CT", "Connecticut" ));
    arrList.Add(new KeyValuePair<string, string>("DE", "Delaware" ));
    arrList.Add(new KeyValuePair<string, string>("DC", "District Of Columbia" ));
    arrList.Add(new KeyValuePair<string, string>("FL", "Florida" ));
    arrList.Add(new KeyValuePair<string, string>("GA", "Georgia" ));
    arrList.Add(new KeyValuePair<string, string>("HI", "Hawaii" ));
    arrList.Add(new KeyValuePair<string, string>("ID", "Idaho" ));
    arrList.Add(new KeyValuePair<string, string>("IL", "Illinois" ));
    arrList.Add(new KeyValuePair<string, string>("IN", "Indiana" ));
    arrList.Add(new KeyValuePair<string, string>("IA", "Iowa" ));
    arrList.Add(new KeyValuePair<string, string>("KS", "Kansas" ));
    arrList.Add(new KeyValuePair<string, string>("KY", "Kentucky" ));
    arrList.Add(new KeyValuePair<string, string>("LA", "Louisiana" ));
    arrList.Add(new KeyValuePair<string, string>("ME", "Maine" ));
    arrList.Add(new KeyValuePair<string, string>("MD", "Maryland" ));
    arrList.Add(new KeyValuePair<string, string>("MA", "Massachusetts" ));
    arrList.Add(new KeyValuePair<string, string>("MI", "Michigan" ));
    arrList.Add(new KeyValuePair<string, string>("MN", "Minnesota" ));
    arrList.Add(new KeyValuePair<string, string>("MS", "Mississippi" ));
    arrList.Add(new KeyValuePair<string, string>("MO", "Missouri" ));
    arrList.Add(new KeyValuePair<string, string>("MT", "Montana" ));
    arrList.Add(new KeyValuePair<string, string>("NE", "Nebraska" ));
    arrList.Add(new KeyValuePair<string, string>("NV", "Nevada" ));
    arrList.Add(new KeyValuePair<string, string>("NH", "New Hampshire" ));
    arrList.Add(new KeyValuePair<string, string>("NJ", "New Jersey" ));
    arrList.Add(new KeyValuePair<string, string>("NM", "New Mexico" ));
    arrList.Add(new KeyValuePair<string, string>("NY", "New York" ));
    arrList.Add(new KeyValuePair<string, string>("NC", "North Carolina" ));
    arrList.Add(new KeyValuePair<string, string>("ND", "North Dakota" ));
    arrList.Add(new KeyValuePair<string, string>("OH", "Ohio" ));
    arrList.Add(new KeyValuePair<string, string>("OK", "Oklahoma" ));
    arrList.Add(new KeyValuePair<string, string>("OR", "Oregon" ));
    arrList.Add(new KeyValuePair<string, string>("PA", "Pennsylvania" ));
    arrList.Add(new KeyValuePair<string, string>("RI", "Rhode Island" ));
    arrList.Add(new KeyValuePair<string, string>("SC", "South Carolina" ));
    arrList.Add(new KeyValuePair<string, string>("SD", "South Dakota" ));
    arrList.Add(new KeyValuePair<string, string>("TN", "Tennessee" ));
    arrList.Add(new KeyValuePair<string, string>("TX", "Texas" ));
    arrList.Add(new KeyValuePair<string, string>("UT", "Utah" ));
    arrList.Add(new KeyValuePair<string, string>("VT", "Vermont" ));
    arrList.Add(new KeyValuePair<string, string>("VA", "Virginia" ));
    arrList.Add(new KeyValuePair<string, string>("WA", "Washington" ));
    arrList.Add(new KeyValuePair<string, string>("WV", "West Virginia" ));
    arrList.Add(new KeyValuePair<string, string>("WI", "Wisconsin" ));
    arrList.Add(new KeyValuePair<string, string>("WY", "Wyoming" ));
    return arrList;
}

Answer 2

Html.CheckBoxFor（）扩展方法旨在编辑模型的boolean类型的属性。您想使用它从IEnumerable集合中选择一些对象。这是错的。

正确的方式：

在视图中

<form action="/Customer/Process">
<% foreach (var customer in Model.Request.Customers)
   { %>
        <input type="checkbox" name="selectedId" value="<%= customer.id %>" />
        <%= customer.name %>
        <br/>
<% } %>
        <input type="submit"/>
</form>

控制器中的

public string Process(IEnumerable<Guid> selectedId)
{
    if (selectedId == null)
    {
        ModelState.AddModelError("selectedId", "Have to select at least one customer!");

        return View();
    }

    // do something with customers' ids
}

Answer 3

我使用了一个助手类。这真的很简单。使用帮助程序类，您可以使用SelectList并将其放在帮助程序中，就像您为下拉列表所做的那样。

在文件夹“Helpers”中我有Checkboxlist.cs

    using System;
    using System.Web.Mvc;
    using System.Collections.Generic;
    using System.Text;
    using System.Linq;

    namespace MVC2_NASTEST.Helpers {
        public static class CheckBoxListHelper {

            public static string CheckBoxList(this HtmlHelper helper, string name, IDictionary<string, string> items) {
                return CheckBoxList(helper, name, items, null, null);
            }

            public static string CheckBoxList(this HtmlHelper helper, string name, IDictionary<string, string> items, IDictionary<string, object> checkboxHtmlAttributes) {
                return CheckBoxList(helper, name, items, null, checkboxHtmlAttributes);
            }

            public static string CheckBoxList(this HtmlHelper helper, string name, IDictionary<string, string> items, IEnumerable<string> selectedValues) {
                return CheckBoxList(helper, name, items, selectedValues, null);
            }

            public static string CheckBoxList(this HtmlHelper helper, string name, IDictionary<string, string> items, IEnumerable<string> selectedValues, IDictionary<string, object> checkboxHtmlAttributes) {

                var selectListItems = from i in items
                                      select new SelectListItem {
                                          Text = i.Key,
                                          Value = i.Value,
                                          Selected = (selectedValues != null && selectedValues.Contains(i.Value))
                                      };

                return CheckBoxList(helper, name, selectListItems, checkboxHtmlAttributes);
            }

            public static string CheckBoxList(this HtmlHelper helper, string name, IEnumerable<SelectListItem> items) {
                return CheckBoxList(helper, name, items, null);
            }

            public static string CheckBoxList(this HtmlHelper helper, string name, IEnumerable<SelectListItem> items, IDictionary<string, object> checkboxHtmlAttributes) {
                var output = new StringBuilder();

                foreach (var item in items) {
                    output.Append("<div class=\"fields\"><label>");
                    var checkboxList = new TagBuilder("input");
                    checkboxList.MergeAttribute("type", "checkbox");
                    checkboxList.MergeAttribute("name", name);
                    checkboxList.MergeAttribute("value", item.Value);

                    // Check to see if it's checked
                    if (item.Selected)
                        checkboxList.MergeAttribute("checked", "checked");

                    // Add any attributes
                    if (checkboxHtmlAttributes != null)
                        checkboxList.MergeAttributes(checkboxHtmlAttributes);

                    checkboxList.SetInnerText(item.Text);
                    output.Append(checkboxList.ToString(TagRenderMode.SelfClosing));
                    output.Append("&nbsp; " + item.Text + "</label></div>");
                }

                return output.ToString();
            }
        }
    }

我控制器中的代码：

    public static List<SelectListItem> lesgeverList() {
        return lesgeverList(-1);
    }

    public static List<SelectListItem> lesgeverList(int selectedID) {
        return lesgeverList(new int[] { selectedID });
    }

    public static List<SelectListItem> lesgeverList(int[] lg) {
        NASDataContext _db = new NASDataContext();
        var lesg = (from l in _db.Lesgevers
                    where l.LG_Naam != "leeg"
                    orderby l.LG_Naam, l.LG_Vnaam
                    select l).ToSelectList(m => m.LG_Naam + " " + m.LG_Vnaam, m => m.LG_ID.ToString(), m => lg.Contains(m.LG_ID));
        return lesg.ToList();
    }

    //
    // GET: /Projectleiders/Create

    public ActionResult Create(int projID) {
        ViewData["projNaam"] = getProject(projID).Proj_Kortenaam;
        int[] keys = (from p in _db.ProjectleiderProjectens
                      where p.Proj_ID == projID
                      from l in _db.Lesgevers
                      where p.LG_ID == l.LG_ID
                      select l.LG_ID).ToArray();

        ViewData["projleiders"] = MvcApplication.lesgeverList(keys);

        return toegankelijk(projID, null);
    }

    //
    // POST: /Projectleiders/Create

    [HttpPost]
    public ActionResult Create(FormCollection collection, int projID) {

        if (collection["lesgeverlist"] != null) {
            string[] lgevers = collection["lesgeverlist"].Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
            List<ProjectleiderProjecten> lst = new List<ProjectleiderProjecten>();
            foreach (string s in lgevers) {
                ProjectleiderProjecten prl = new ProjectleiderProjecten();
                prl.LG_ID = int.Parse(s);
                prl.Proj_ID = projID;

                int count = (from m in _db.ProjectleiderProjectens
                             where m.LG_ID == prl.LG_ID && m.Proj_ID == prl.Proj_ID
                             select m).Count();

                if (count <= 0) {
                    //deze bestaat nog niet
                    lst.Add(prl);
                }
            }
            //var test = _db.ProjectleiderProjectens.Where(p => p.Proj_ID == projID && !lgevers.Contains(p.LG_ID.ToString())).ToList();

            _db.ProjectleiderProjectens.DeleteAllOnSubmit(_db.ProjectleiderProjectens.Where(p => p.Proj_ID == projID && !lgevers.Contains(p.LG_ID.ToString())));

            _db.ProjectleiderProjectens.InsertAllOnSubmit(lst);
            _db.SubmitChanges();

            return RedirectToAction("Index");
        } else {

            ModelState.AddModelError("lesgeverlist", "Je hebt geen lesgevers geselecteerd");

            ViewData["projleiders"] = MvcApplication.lesgeverList();
            ViewData["projNaam"] = getProject(projID).Proj_Kortenaam;
            return View();
        }
    }

我使用ToSelectList扩展，这是每个人都应该拥有的。

public static class VSKOExtensions {
    public static IList<SelectListItem> ToSelectList<T>(this IEnumerable<T> itemsToMap, Func<T, string> textProperty, Func<T, string> valueProperty, Predicate<T> isSelected) {
        var result = new List<SelectListItem>();

        foreach (var item in itemsToMap) {
            result.Add(new SelectListItem {
                Value = valueProperty(item),
                Text = textProperty(item),
                Selected = isSelected(item)
            });
        }
        return result;
    }
}

我的创建视图中的代码（同时也是一个编辑视图）非常简单

    <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MVC2_NASTEST.Models.ProjectleiderProjecten>" %>
    <%@ Import Namespace="MVC2_NASTEST.Helpers" %>

    <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
        Create
    </asp:Content>

    <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

        <h2>Koppel projectleider voor
            <%= ViewData["projNaam"].ToString() %></h2>

        <% using (Html.BeginForm()) {%>
            <%= Html.ValidationSummary(true) %>

            <fieldset>
                <legend>Fields</legend>

                <div class="editor-label">
                    <%= Html.Label("Lesgevers")%>
                </div>
                <div class="editor-field">
                    <%= Html.CheckBoxList("Lesgeverlist", ViewData["projleiders"] as List<SelectListItem>)%>
                    <%= Html.ValidationMessage("Lesgeverlist")%>
                </div>

                <p>
                    <input type="submit" value="Create" />
                </p>
            </fieldset>

        <% } %>

        <div>
            <%= Html.ActionLink("Back to List", "Index") %>
        </div>

    </asp:Content>

它如何运作：

我从已经选择的用户的DB中获取值，获取他们的id并将其提供给方法MvcApplication.lesgeverList（keys）;

然后我将选择列表返回，将其放入viewdata中，当我打开它时，在我的视图中选择了所选人员。然后，当我更改一些框并保存它时，我检查集合是否为空（所以选择了某些东西）然后我拆分我得到的变量，这是你在SelectList中给出的值。我预先通过它们，将它们解析为整数，从DB中获取用户的解析ID。通过计数，我会查看它们是否存在于'链接'表中，该表称为_db.ProjectleiderProjectens

当添加所有内容时，我使用linq语句删除所有'未选中'的1次

   _db.ProjectleiderProjectens.DeleteAllOnSubmit(_db.ProjectleiderProjectens.Where(p => p.Proj_ID == projID && !lgevers.Contains(p.LG_ID.ToString())));

我觉得这很可读。从中删除所有对象，获取所有对象的ID，并检查哪些不在ID

的字符串[]中

它必须说得很好。如果你还有其他问题，请问。

Answer 4

只需在客户端使用jQuery验证，然后在服务器端仔细检查自己，只需确保表单集合中填充了值。

你的for循环没有任何问题。