使用JQuery自动完成插件Auto Complete详解

2019-11-19 11:18:54

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来源：转载

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问题

当你查找一些特殊的东西，当你输入准确的词时，找到它可能是困难的（或者很耗时）。在输入的时候展示出结果（自动完成），使查找变得更简单。

解决方案

使用JQuery自动完成插件，更新现有图书列表页面上的搜索，当用户键入的时候立即显示结果。

讨论

自动完成插件是不会象jQuery基本库一样自动包含在MVC项目中的，所以需要做的第一件事就是的是下载插件
访问http://jquery.com/。两个主要的文件是必需的：JavaScript文件和CSS文件。把新下载的javascript文件放到你MVC应用程序的script 文件夹下。CSS文件可以直接添加到您的content目录。

这个配方也将介绍在view中使用 rendering sections。在shared文件夹下layout中自动添加了2个javascript文件和1个css文件。这些是Ajax和不唐突的Ajax和网站主css文件。每次加载的内容越多，页面视图加载越慢。与其在每个页面都去包含可能不必要的javascript和css 文件，不如在layout中添加一个新的RenderSection()。这允许特别的view在<head>标签去加载特别的javascript或css，但不是每页都添加他们。

下边是一个更新后的Views/Shared/_Layout.cshtml，他使用了一个新的RenderSection（）。

<!DOCTYPE html><html><head><title>_Mobile</title><link href="@Url.Content(" rel="external nofollow" rel="external nofollow" ~/Content/Site.css")" rel="stylesheet" type="text/css" /><script src="@Url.Content("~/Scripts/jquery-1.6.2.min.js")" type="text/javascript"></script><script type="text/javascript">$(document).ready(function () {if (window.innerWidth <= 480) {$("link[rel=stylesheet]").attr({ href: "@Url.Content("~/Content/jquery.mobile-1.0b1.min.css")" });}});</script>@RenderSection("JavaScriptAndCSS", required: false)</head><body><div class="page" data-role="page"><div id="header" data-role="header"><div id="title"><h1>My MVC Application</h1></div><div id="logindisplay" class="ui-bar">@Html.Partial("_LogOnPartial")[ @Html.ActionLink("English", "ChangeLanguage", "Home", new { language = "en" }, null) ][ @Html.ActionLink("Français", "ChangeLanguage", "Home", new { language = "fr" }, null) ]</div><div id="menucontainer" class="ui-bar"><ul id="menu"><li>@Html.ActionLink("Home", "Index", "Home", null, new Dictionary<string, object> {{ "data-role", "button" }})</li><li>@Html.ActionLink("About", "About", "Home", null, new Dictionary<string, object> { { "data-role", "button" }})</li></ul></div></div><div id="main" data-role="content">@RenderBody()</div><div id="footer" data-role="footer"></div></div></body></html>

主要的CSS文件和核心的JQuery文件被留下来了，因为css在每个也都需要，并且绝大多数网页也需要JQuery。然而新的JQuery文件和不唐突的AJAX不是每个页面都需要的。

现在，有两种方式使用Autocomplete 插件：

1.在javascript中设置要搜索的数据。

2.当用户输入时通过ajax检索。

在我使用这个插件的经验看来，我发现使用解决方案1时自动完成更快。因为它并不需要每次从数据库中请求数据。然而，使用这种解决方案的限制：只有这么多字符，可传递到function中，大量的JavaScript可能会导致用户的计算机上页面加载缓慢。经过一些试验和错误，我已经确定神奇的数字是大约40,000个结果。如果结果数量超过此，最好使用选项2;否则，始终坚持，因为搜索选项1是瞬时，而不是有轻微的延迟。

在这个例子中，将搜索书籍，我们没有超过40000，所以将使用选项1。BooksController现在必须更新，以设置ViewBag为book title。自动完成功能需要支持一个JavaScript数组的支持，所以书将管道（|）分开。然后在view中，书将被转换到一个数组，使用JavaScript的split（）函数。当用户完成键入他们的结果，他们应该有选择完全匹配标题，因此这个函数将被更新。如果只有1本书返回并且用户执行了搜索，它会自动重定向到本书详细介绍页面。

我们要在bookcontroller 中更新Index Action 并添加一个私有方法名为：FormatBooksForAutocomplete。

代码如下：

using System;using System.Collections.Generic;using System.Data;using System.Data.Entity;using System.Linq;using System.Linq.Dynamic;using System.Web;using System.Web.Mvc;using MvcApplication.Models;using MvcApplication.Utils;using PagedList;namespace MvcApplication.Controllers{ public class BooksController : Controller{private BookDBContext db = new BookDBContext();//// GET: /Books/[OutputCache(Duration = Int32.MaxValue, SqlDependency = "MvcApplication.Models.BookDBContext:books", VaryByParam = "sortOrder;filter;page")]public ActionResult Index(string sortOrder, string filter, string Keyword, int page = 1){#region ViewBag ResourcesViewBag.Title = Resources.Resource1.BookIndexTitle;ViewBag.CreateLink = Resources.Resource1.CreateLink;ViewBag.TitleDisplay = Resources.Resource1.TitleDisplay;ViewBag.IsbnDisplay = Resources.Resource1.IsbnDisplay;ViewBag.SummaryDisplay = Resources.Resource1.SummaryDisplay;ViewBag.AuthorDisplay = Resources.Resource1.AuthorDisplay;ViewBag.ThumbnailDisplay = Resources.Resource1.ThumbnailDisplay;ViewBag.PriceDisplay = Resources.Resource1.PriceDisplay;ViewBag.PublishedDisplay = Resources.Resource1.PublishedDisplay;ViewBag.EditLink = Resources.Resource1.EditLink;ViewBag.DetailsLink = Resources.Resource1.DetailsLink;ViewBag.DeleteLink = Resources.Resource1.DeleteLink;#endregion#region ViewBag Sort ParamsViewBag.TitleSortParam = (sortOrder == "Title") ? "Title desc" : "Title";ViewBag.IsbnSortParam = (sortOrder == "Isbn") ? "Isbn desc" : "Isbn";ViewBag.AuthorSortParam = (sortOrder == "Author") ? "Author desc" : "Author";ViewBag.PriceSortParam = (sortOrder == "Price") ? "Price desc" : "Price";ViewBag.PublishedSortParam = (String.IsNullOrEmpty(sortOrder)) ? "Published desc" : "";// Default the sort orderif (String.IsNullOrEmpty(sortOrder)){sortOrder = "Published desc";}ViewBag.CurrentSortOrder = sortOrder;#endregionvar books = from b in db.Books select b;#region Keyword Searchif (!String.IsNullOrEmpty(Keyword)){books = books.Where(b => b.Title.ToUpper().Contains(Keyword.ToUpper()) || b.Author.ToUpper().Contains(Keyword.ToUpper()));// Should we redirect because of only one result?if (books.Count() == 1){Book book = books.First();return RedirectToAction("Details", new { id = book.ID });}}ViewBag.CurrentKeyword = String.IsNullOrEmpty(Keyword) ? "" : Keyword;#endregion#region Filter switchswitch (filter){case "NewReleases":var startDate = DateTime.Today.AddDays(-14);books = books.Where(b => b.Published <= DateTime.Today.Date && b.Published >= startDate);break;case "ComingSoon":books = books.Where(b => b.Published > DateTime.Today.Date);break;default:// No filter neededbreak;}ViewBag.CurrentFilter = String.IsNullOrEmpty(filter) ? "" : filter;#endregionbooks = books.OrderBy(sortOrder);int maxRecords = 1;int currentPage = page - 1;// Get all book titlesViewBag.BookTitles = FormatBooksForAutocomplete();return View(books.ToPagedList(currentPage, maxRecords));}private string FormatBooksForAutocomplete(){string bookTitles = String.Empty;var books = from b in db.Books select b;foreach (Book book in books){if (bookTitles.Length > 0){bookTitles += "|";}bookTitles += book.Title;}return bookTitles;}//// GET: /Books/Details/5public ActionResult Details(int id = 0, string bookTitle = ""){Book book = db.Books.Find(id);return View(book);}//// GET: /Books/Createpublic ActionResult Create(){return View();} //// POST: /Books/Create[HttpPost]public ActionResult Create(Book book, HttpPostedFileBase file){if (ModelState.IsValid){// Upload our filebook.Thumbnail = FileUpload.UploadFile(file);db.Books.Add(book);db.SaveChanges();return RedirectToAction("Index"); }return View(book);}//// GET: /Books/Edit/5public ActionResult Edit(int id){Book book = db.Books.Find(id);return View(book);}//// POST: /Books/Edit/5[HttpPost]public ActionResult Edit(Book book, HttpPostedFileBase file){if (ModelState.IsValid){// Delete old fileFileUpload.DeleteFile(book.Thumbnail);// Upload our filebook.Thumbnail = FileUpload.UploadFile(file);db.Entry(book).State = EntityState.Modified;db.SaveChanges();return RedirectToAction("Index");}return View(book);}//// GET: /Books/Delete/5public ActionResult Delete(int id){Book book = db.Books.Find(id);return View(book);}//// POST: /Books/Delete/5[HttpPost, ActionName("Delete")]public ActionResult DeleteConfirmed(int id){ Book book = db.Books.Find(id);// Delete old fileFileUpload.DeleteFile(book.Thumbnail);db.Books.Remove(book);db.SaveChanges();return RedirectToAction("Index");}protected override void Dispose(bool disposing){db.Dispose();base.Dispose(disposing);}}}

最后book/index view需要更新去初始化jQuery的自动完成。要做的第一件事是使用@节标记，包括必要的JavaScript和CSS文件。接下来，以前创建的搜索文本框更新设置一个键的IDwordSearch。

最后，JavaScript代码添加在视图的底部去在搜索文本框上建立自动完成功能。此JavaScript是有意添加在view的底部，以确保完全呈现给用户，因为在用户的电脑上建立数据是一项工作，Javascript处理可能会“堵塞”页面加载。

（译者：先呈现数据再执行javascript，js不是像传统那样放在head标签里）

这取决于结果的数量。代码如下：

@model PagedList.IPagedList<MvcApplication.Models.Book>@if (IsAjax){Layout = null;}@section JavascriptAndCSS {<link rel="stylesheet" href="@Url.Content(" rel="external nofollow" rel="external nofollow" ~/Content/jquery.autocomplete.css")" type="text/css" /><script type="text/javascript" src="@Url.Content("~/Scripts/jquery.autocomplete.js")"></script><script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>}<h2>@MvcApplication4.Resources.Resource1.BookIndexTitle</h2><p>@Html.ActionLink("Create New", "Create")</p><p>Show:@if (ViewBag.CurrentFilter != ""){@Ajax.ActionLink("All", "Index", new { sortOrder = ViewBag.CurrentSortOrder, Keyword = ViewBag.CurrentKeyword }, new AjaxOptions { UpdateTargetId = "main" })}else{@:All}  |  @if (ViewBag.CurrentFilter != "NewReleases"){@Ajax.ActionLink("New Releases", "Index", new { filter = "NewReleases", sortOrder = ViewBag.CurrentSortOrder, Keyword = ViewBag.CurrentKeyword }, new AjaxOptions { UpdateTargetId = "main" })}else{@:New Releases}  |  @if (ViewBag.CurrentFilter != "ComingSoon"){@Ajax.ActionLink("Coming Soon", "Index", new { filter = "ComingSoon", sortOrder = ViewBag.CurrentSortOrder, Keyword = ViewBag.CurrentKeyword }, new AjaxOptions { UpdateTargetId = "main" })}else{@:Coming Soon}</p>@using (Html.BeginForm()){@:Search: @Html.TextBox("Keyword", (string)ViewBag.CurrentKeyword, new { id = "KeywordSearch" }) <input type="submit" value="Search" />}@Html.Partial("_Paging")<table><tr><th>@Ajax.ActionLink("Title", "Index", new { sortOrder = ViewBag.TitleSortParam, filter = ViewBag.CurrentFilter, Keyword = ViewBag.CurrentKeyword }, new AjaxOptions { UpdateTargetId = "main" })</th><th>@Ajax.ActionLink("Isbn", "Index", new { sortOrder = ViewBag.IsbnSortParam, filter = ViewBag.CurrentFilter, Keyword = ViewBag.CurrentKeyword }, new AjaxOptions { UpdateTargetId = "main" })</th><th>Summary</th><th>@Ajax.ActionLink("Author", "Index", new { sortOrder = ViewBag.AuthorSortParam, filter = ViewBag.CurrentFilter, Keyword = ViewBag.CurrentKeyword }, new AjaxOptions { UpdateTargetId = "main" })</th><th>Thumbnail</th><th>@Ajax.ActionLink("Price", "Index", new { sortOrder = ViewBag.PriceSortParam, filter = ViewBag.CurrentFilter, Keyword = ViewBag.CurrentKeyword }, new AjaxOptions { UpdateTargetId = "main" })</th><th>@Ajax.ActionLink("Published", "Index", new { sortOrder = ViewBag.PublishedSortParam, filter = ViewBag.CurrentFilter, Keyword = ViewBag.CurrentKeyword }, new AjaxOptions { UpdateTargetId = "main" })</th><th></th></tr>@foreach (var item in Model){<tr><td>@Html.DisplayFor(modelItem => item.Title)</td><td>@Html.DisplayFor(modelItem => item.Isbn)</td><td>@Html.DisplayFor(modelItem => item.Summary)</td><td>@Html.DisplayFor(modelItem => item.Author)</td><td>@Html.DisplayFor(modelItem => item.Thumbnail)</td><td>@Html.DisplayFor(modelItem => item.Price)</td><td>@Html.DisplayFor(modelItem => item.Published)</td><td>@Html.ActionLink("Edit", "Edit", new { id = item.ID }) |@Html.ActionLink("Details", "Details", new { id = item.ID }) |@Html.ActionLink("Delete", "Delete", new { id = item.ID })</td></tr>}</table>@Html.Partial("_Paging")<script type="text/javascript">$(document).ready(function () {var data = "@ViewBag.BookTitles".split("|");$("#KeywordSearch").autocomplete(data);});</script>

为了实施选项2，一个Ajax搜索，而不是传递数据数组到自动完成函数，您可以传递一个URL。URL将需要接受查询字符串变量：q。这包含用户输入的搜索值。这将用于执行书本上包含部分匹配的搜索，并返回以分隔符分隔的字符串。JQuery文档中含有较多的这样的成品例子，也有其他的例子，去更新的输出结果（可能包括书的封面的缩略图）。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。

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