MVC批量更新,使用jQuery Template

在"MVC批量更新,可验证并解决集合元素不连续控制器接收不完全的问题"中，当点击"添加"按钮的时候，通过部分视图，在界面上添加新行。本篇体验使用jQuery Template，在界面上添加新行。

□ 思路

→引用jQuery Template所需要的js文件：jquery.tmpl.min.js
→在<script type="text/x-jquery-tmpl" id="movieTemplate"></script>中生成模版内容，里面包含占位符
→点击添加按钮的时候，把模版内容追加到界面上，并给占位符赋值

 

□ jQuery Template的内容大致是这样：

<script type="text/x-jquery-tmpl" id="movieTemplate">
<li style="padding-bottom:15px">

    <input autocomplete="off" name="FavouriteMovies.Index" type="hidden" value="${index}" />

    <img src="/Content/images/draggable-icon.png" style="cursor: move" alt=""/>

    <label>Title</label>
    <input name="FavouriteMovies[${index}].Title" type="text" value="" />

    <label>Rating</label>
    <input name="FavouriteMovies[${index}].Rating" type="text" value="0" />

    <a href="#" onclick="$(this).parent().remove();">Delete</a>
</li>
</script>

为了得到以上内容，由帮助类方法获得：

    <script type="text/x-jquery-tmpl" id="movieTemplate">
            @Html.CollectionItemJQueryTemplate("MovieEntryEditor", new Movie())
    </script>

 

帮助类CollectionEditingHtmlExtensions：
模版内容同样是通过MovieEntryEditor.cshtml这个部分视图生成的，只不过生成的内容中包含了占位符。

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Html;

namespace VariableCollection.Extension
{
    public static class CollectionEditingHtmlExtensions
    {
        /// <summary>
        /// 目标是生成如下格式
        ///<input autocomplete="off" name="FavouriteMovies.Index" type="hidden" value="6d85a95b-1dee-4175-bfae-73fad6a3763b" />
        ///<label>Title</label>
        ///<input class="text-box single-line" name="FavouriteMovies[6d85a95b-1dee-4175-bfae-73fad6a3763b].Title" type="text" value="Movie 1" />
        ///<span class="field-validation-valid"></span>
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <param name="html"></param>
        /// <param name="collectionName">集合属性的名称</param>
        /// <returns></returns>
        public static IDisposable BeginCollectionItem<TModel>(this HtmlHelper<TModel> html, string collectionName)
        {
            if (string.IsNullOrEmpty(collectionName))
            {
                throw new ArgumentException("collectionName is null or empty","collectionName");
            }
            string collectionIndexFieldName = String.Format("{0}.Index", collectionName);//FavouriteMovies.Index
            string itemIndex = null;
            if (html.ViewData.ContainsKey(JQueryTemplatingEnabledKey))
            {
                itemIndex = "${index}";
            }
            else
            {
                itemIndex = GetCollectionItemIndex(collectionIndexFieldName);
            }

            //比如，FavouriteMovies[6d85a95b-1dee-4175-bfae-73fad6a3763b]
            string collectionItemName = string.Format("{0}[{1}]", collectionName, itemIndex);

            TagBuilder indexField = new TagBuilder("input");
            indexField.MergeAttributes(new Dictionary<string, string>() {
                { "name", String.Format("{0}.Index", collectionName) }, //name="FavouriteMovies.Index"
                { "value", itemIndex },//value="6d85a95b-1dee-4175-bfae-73fad6a3763b"
                { "type", "hidden" },
                { "autocomplete", "off" }
            });
            html.ViewContext.Writer.WriteLine(indexField.ToString(TagRenderMode.SelfClosing));

            return new CollectionItemNamePrefixScope(html.ViewData.TemplateInfo, collectionItemName);
        }

         private class CollectionItemNamePrefixScope : IDisposable
         {
             private readonly TemplateInfo _templateInfo;
             private readonly string _previousPrefix;

             public CollectionItemNamePrefixScope(TemplateInfo templateInfo, string collectionItemName)
             {
                 this._templateInfo = templateInfo;
                 _previousPrefix = templateInfo.HtmlFieldPrefix;
                 templateInfo.HtmlFieldPrefix = collectionItemName;
             }

             public void Dispose()
             {
                 _templateInfo.HtmlFieldPrefix = _previousPrefix;
             }
         }

        /// <summary>
        /// 以FavouriteMovies.Index为键，把Guid字符串存放在上下文中
        /// 如果是添加进入部分视图，就直接生成一个Guid字符串
        /// 如果是更新，为了保持和ModelState的一致，就遍历原先的Guid
        /// </summary>
        /// <param name="collectionIndexFieldName">FavouriteMovies.Index</param>
        /// <returns>返回Guid字符串</returns>
        private static string GetCollectionItemIndex(string collectionIndexFieldName)
        {
            Queue<string> previousIndices = (Queue<string>)HttpContext.Current.Items[collectionIndexFieldName];
            if (previousIndices == null)
            {
                HttpContext.Current.Items[collectionIndexFieldName] = previousIndices = new Queue<string>();
                string previousIndicesValues = HttpContext.Current.Request[collectionIndexFieldName];
                if (!string.IsNullOrWhiteSpace(previousIndicesValues))
                {
                    foreach (string index in previousIndicesValues.Split(','))
                    {
                        previousIndices.Enqueue(index);
                    }
                }
            }
            return previousIndices.Count > 0 ? previousIndices.Dequeue() : Guid.NewGuid().ToString();
        }

        private const string JQueryTemplatingEnabledKey = "__BeginCollectionItem_jQuery";
        public static MvcHtmlString CollectionItemJQueryTemplate<TModel, TCollectionItem>(this HtmlHelper<TModel> html,
                                                                                    string partialViewName,
                                                                                    TCollectionItem modelDefaultValues)
        {
            ViewDataDictionary<TCollectionItem> viewData = new ViewDataDictionary<TCollectionItem>(modelDefaultValues);
            viewData.Add(JQueryTemplatingEnabledKey, true);
            return html.Partial(partialViewName, modelDefaultValues, viewData);
        }
    }
}

□ MovieEntryEditor.cshtm部分视图与上篇相同

@using VariableCollection.Extension
@model VariableCollection.Models.Movie

<li style="padding-bottom: 15px;">
    @using (Html.BeginCollectionItem("FavouriteMovies"))
    {
        <img src="@Url.Content("~/Content/images/draggable-icon.png")" style="cursor: move" alt=""/>

        @Html.LabelFor(model => model.Title)
        @Html.EditorFor(model => model.Title)
        @Html.ValidationMessageFor(model => model.Title)

        @Html.LabelFor(model => model.Rating)
        @Html.EditorFor(model => model.Rating)
        @Html.ValidationMessageFor(model => model.Rating)

        <a href="#" onclick=" $(this).parent().remove(); ">删除行</a>
    }
</li>

 

□ HomeController

        public ActionResult EditJqueryTemplate()
        {
            return View(CurrentUser);
        }

        [HttpPost]
        public ActionResult EditJqueryTemplate(User user)
        {
            if (!this.ModelState.IsValid)
            {
                return View(user);
            }
            CurrentUser = user;
            return RedirectToAction("Display");
        }

 

□ EditJqueryTemplate.cshtml完整代码如下：

@using VariableCollection.Extension
@using VariableCollection.Models
@model VariableCollection.Models.User

@{
    ViewBag.Title = "EditJqueryTemplate";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>EditJqueryTemplate</h2>

@using (Html.BeginForm())
{
    @Html.ValidationSummary(true)
    <fieldset>
        <legend>最喜欢看的电影</legend>
        @Html.HiddenFor(model => model.Id)
        <div class="editor-label">
            @Html.LabelFor(model => model.Name)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.Name)
            @Html.ValidationMessageFor(model => model.Name)
        </div>
    </fieldset>

    <fieldset>
        <legend>最喜欢看的电影</legend>
        @if (Model.FavouriteMovies == null || Model.FavouriteMovies.Count == 0)
        {
            <p>没有喜欢看的电影~~</p>
        }
        <ul id="movieEditor" style="list-style-type: none">
            @if (Model.FavouriteMovies != null)
            {
                foreach (Movie movie in Model.FavouriteMovies)
                {
                    Html.RenderPartial("MovieEntryEditor", movie);
                }
            }
        </ul>

        <a id="addAnother" href="#" >添加</a>
    </fieldset>
    <p>
        <input type="submit" value="提交" />
    </p>
}

@section scripts
{
    <script src="~/Scripts/jquery.tmpl.min.js"></script>

    <script type="text/x-jquery-tmpl" id="movieTemplate">
            @Html.CollectionItemJQueryTemplate("MovieEntryEditor", new Movie())
    </script>

    <script type="text/javascript">
            $(function () {
                $("#movieEditor").sortable();

                $('#addAnother').click(function() {
                    viewModel.addNew();
                });
            });

            var viewModel = {
                addNew: function () {
                    $("#movieEditor").append($("#movieTemplate").tmpl({ index: viewModel._generateGuid() }));
                },

                _generateGuid: function () {
                    // Source: http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript/105074#105074
                    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
                        var r = Math.random() * 16 | 0, v = c == 'x' ? r : (r & 0x3 | 0x8);
                        return v.toString(16);
                    });
                }
            };
    </script>
}

参考资料：
※ Editing Variable Length Reorderable Collections in ASP.NET MVC – Part 2: jQuery Templates