【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

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。