【译】MVC3 20个秘方-（10）根据关键字搜索

问题

当排序和分页和过滤都不够帮用户去找到他们想要的结果时，想一个最好的备选方式是让用户输入（关键字）他们想要什么。

解决方案

用HtmlHelper创建一个新的From和 文本输入框，并且借助LINQ根据用户输入的关键字在之前过滤过的结果里查找。

讨论

和前边的秘方很像，添加一个根据keyword 搜索的功能需要更新Book/Index view 和BookController。在View里添加一个新的from和textbox 让用户输入keyword。同时也要确保当用户改变排序规则、过滤、分页时，关键字保持。

下边的代码是对View的更新：

@model PagedList.IPagedList<MvcApplication.Models.Book>

<h2>@MvcApplication4.Resources.Resource1.BookIndexTitle</h2>

<p>

    @Html.ActionLink("Create New", "Create")

</p>

<p>

    Show:

    @if (ViewBag.CurrentFilter != "")

    {

        @Html.ActionLink("All", "Index", new

   {

       sortOrder = ViewBag.CurrentSortOrder,

       Keyword = ViewBag.CurrentKeyword

   })

    }

    else

    {

        @:All

                }

    &nbsp; | &nbsp;

    @if (ViewBag.CurrentFilter != "NewReleases")

    {

        @Html.ActionLink("New Releases", "Index", new

   {

       filter = "NewReleases",

       sortOrder = ViewBag.CurrentSortOrder,

       Keyword = ViewBag.CurrentKeyword

   })

    }

    else

    {

        @:New Releases

                }

    &nbsp; | &nbsp;

    @if (ViewBag.CurrentFilter != "ComingSoon")

    {

        @Html.ActionLink("Coming Soon", "Index", new

   {

       filter = "ComingSoon",

       sortOrder = ViewBag.CurrentSortOrder,

       Keyword = ViewBag.CurrentKeyword

   })

    }

    else

    {

        @:Coming Soon

                }

</p>

@using (Html.BeginForm())

{

    @:Search: @Html.TextBox("Keyword")<input type="submit" value="Search" />

}

@Html.Partial("_Paging")

<table>

    <tr>

        <th>

            @Html.ActionLink("Title", "Index", new

       {

           sortOrder = ViewBag.TitleSortParam,

           filter = ViewBag.CurrentFilter,

           Keyword = ViewBag.CurrentKeyword

       })

        </th>

        <th>

            @Html.ActionLink("Isbn", "Index", new

       {

           sortOrder = ViewBag.IsbnSortParam,

           filter = ViewBag.CurrentFilter,

           Keyword = ViewBag.CurrentKeyword

       })

        </th>

        <th>

            Summary

        </th>

        <th>

            @Html.ActionLink("Author", "Index", new

       {

           sortOrder = ViewBag.AuthorSortParam,

           filter = ViewBag.CurrentFilter,

           Keyword = ViewBag.CurrentKeyword

       })

        </th>

        <th>

            Thumbnail

        </th>

        <th>

            @Html.ActionLink("Price", "Index", new

       {

           sortOrder = ViewBag.PriceSortParam,

           filter = ViewBag.CurrentFilter,

           Keyword = ViewBag.CurrentKeyword

       })

        </th>

        <th>

            @Html.ActionLink("Published", "Index", new

{

    sortOrder = ViewBag.PublishedSortParam,

    filter = ViewBag.CurrentFilter,

    Keyword = ViewBag.CurrentKeyword

})

        </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")

最终，BookController 需要被更新，在下边的例子，Index（）action 更新 www.2cto.com

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/

        public ViewResult Index(string sortOrder, string filter,string Keyword, int page = 1)

        {

            #region ViewBag Resources

            #endregion

            #region ViewBag Sort Params

            #endregion

            var books = from b in db.Books select b;

            #region Keyword Search

            if (!String.IsNullOrEmpty(Keyword))

            {

                books = books.Where(b =>

                b.Title.ToUpper().Contains(Keyword.ToUpper())

                || b.Author.ToUpper().Contains(

                Keyword.ToUpper()));

            }

            ViewBag.CurrentKeyword =

            String.IsNullOrEmpty(Keyword) ? "" : Keyword;

            #endregion

            #region Filter Switch

            #endregion

            int maxRecords = 1;

            int currentPage = page - 1;

            return View(books.ToPagedList(currentPage,

            maxRecords));

        }

    }

}

译者：上边代码是以书名和作者名为搜索条件的。你也可以自己扩展。比如根据ISBN：

books = books.Where(b =>

                b.Title.ToUpper().Contains(Keyword.ToUpper())

                || b.Author.ToUpper().Contains(

                Keyword.ToUpper()||b.ISBN.ToUpper().Contains(

                Keyword.ToUpper()));

当然这样做的话查询效率会有问题。我们可以在UI提供一个dropdownlist 让用户去选择根据什么条件去搜索关键字。