问题
当你点击链接时,整个的网页都被重新加载。尤其是你仅仅一小点内容需要被更新时,这将被感觉是一个很慢的过程。
解决方案
更新之前创建的HTML.ActionLink 去调用ajax 帮助类。Ajax.ActionLink 仅仅去重新加载那些发生变化的内容。
讨论
MVC提供了几个给力的帮助类。到目前为止,这本书中已经广泛的应用了HTML Helper。在过去创建的所有view中,HTML helper至少都使用过一次。在这个秘方中,我们将使用AjaxHelper类替换掉Book/Index中的HtmlHelper 类。
实现Ajax需要一点额外的设置才可以使用。通常情况下我发现这个额外的工作,可以打消开发人员使用它的念头。我要让大家知道,额外的安装设置是值得的,因为带来的好处是获得了更好的用户体验,这是非常值得努力去做的。
步骤从web.config开始。2个关键的地方要被设置成true. ClientValidationEnabled 和UnobtrusiveJavaScriptEnabled。
译者:原书中代码引入了整个web.config文件。我们只需要到appSettings节点下即可找到这两个keys。
1
2
3
4
5
|
< appSettings > < add key = "webpages:Version" value = "1.0.0.0" /> < add key = "ClientValidationEnabled" value = "true" /> < add key = "UnobtrusiveJavaScriptEnabled" value = "true" /> </ appSettings > |
接下来的步骤是我们要引入几个javascript 文件。我们要在里shared 的layout文件夹里完成这件事,因为几乎我们创建所有的view时都会引用它(布局模板)。在Views/Shared /_Layout.cshtml 文件的<head>标签中。我们引入2个javascript 文件,代码如下:
1
2
3
4
5
6
|
< head > < title >@ViewBag.Title</ title > < link href = "@Url.Content(" ~/Content/Site.css")" rel = "stylesheet" type = "text/css" /> < script src = "@Url.Content(" ~/Scripts/jquery-1.5.1.min.js")" type = "text/javascript" ></ script > < script src = "@Url.Content(" ~/Scripts/jquery.unobtrusive-ajax.min.js")" type = "text/javascript" ></ script > </ head > |
这些文件被自动的包含在基础MVC3应用程序中。(译者:你可以从scripts文件夹中找到他们)。以上的步骤完成AJAX的核心配置。接下来,我们要更新Book/index view。在下边的例子里,三个filter link和sortable header link将用Ajax.ActionLink 替换Html.ActionLink.代码如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
@model PagedList.IPagedList< MvcApplication.Models.Book > @if (IsAjax) { Layout = null; } < h2 > Title</ 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")< 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") |
译者:上边代码标绿的地方就是我们更新的地方。