MVC客户端验证的小示例

配置客户端验证的可用性：

MVC的客户端的验证也利用了实体上的特性标签，如下：

public class Auction
{
[Required]
[StringLength(50,ErrorMessage = "Title cannot be longer than 50 characters")]
public string Title { get; set; }

[Required]
public string Description { get; set; }

[Range(1, 10000,ErrorMessage = "The auction's starting price must be at least 1")]
public decimal StartPrice { get; set; }

public decimal CurrentPrice { get; set; }
public DateTime EndTime { get; set; }
}

被渲染出的View的代码如下：

<h2>Create Auction</h2>
@using (Html.BeginForm())
{
@Html.ValidationSummary()
<p>
  @Html.LabelFor(model => model.Title)
  @Html.EditorFor(model => model.Title)
  @Html.ValidationMessageFor(model => model.Title, "*")
</p>
<p>
  @Html.LabelFor(model => model.Description)
  @Html.EditorFor(model => model.Description)
  @Html.ValidationMessageFor(model => model.Description, "*")
</p>
<p>
  @Html.LabelFor(model => model.StartPrice)
  @Html.EditorFor(model => model.StartPrice)
  @Html.ValidationMessageFor(model => model.StartPrice)
</p>
<p>
  @Html.LabelFor(model => model.EndTime)
  @Html.EditorFor(model => model.EndTime)
  @Html.ValidationMessageFor(model => model.EndTime)
</p>
<p>
<input type="submit" value="Create" />
</p>
}

被渲染出的HTML的代码如下：

<form action="/Auctions/Create" method="post" novalidate="novalidate">
<div class="validation-summary-errors" data-valmsg-summary="true">
  <ul>
   <li>The Description field is required.</li>
   <li>The Title field is required.</li>
   <li>Auction may not start in the past</li>
  </ul>
</div>
<p>
  <label for="Title">Title</label>
  <input class="input-validation-error"
    data-val="true"
    data-val-length="Title cannot be longer than 50 characters"
    data-val-length-max="50"
    data-val-required="The Title field is required."
    >
  </p>
</form>

我们看见在最后生成的HTML代码中多出了很多属性，这时候我们引入两个js文件：
<script src="@Url.Content("~/Scripts/jquery.validate.min.js")"type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")"type="text/javascript"</script>

这两文件会中的代码会根据那些多出的这些属性知道：
哪些input是需要验证的
验证的规则是什么
错误信息是什么
出现错误时应该怎样处理
我们称这个验证方式为隐式验证。