Asp.net mvc 2 in action 笔记- 4 自动代码生成、校验Validation

自动代码生成

T4 (Text Template Transformation Toolkit) is a little-known feature of Visual Studio. It’s a code-generation toolkit, and its templates allow us to customize how files are generated using a familiar syntax.

T4MVC

Out of the box, ASP.NET MVC contains many opportunities to get tripped up with magic strings, especially with URL generation. Magic strings are string constants that are used to represent other constructs, but with an added disconnect that can lead to subtle errors that only show up at runtime. To provide some intelligence around referencing controllers, views, and actions, the T4MVC project helps by generating a hierarchical code model representation for use inside controllers and views.

http://mvccontrib.codeplex.com/wikipage?title=T4MVC

■ T4MVC.tt

■ T4MVC.settings.t4

Html.ActionLink("Log On", "LogOn", "Account")

Html.ActionLink("Log On", MVC.Account.LogOn()

Html.ActionLink("Profile", MVC.Admin.Profile.Show(Html.Encode(Page.User.Identity.Name))

自定义T4模板

www.visualt4.com/downloads.html Visual T4 Editor 可以编辑和建立T4模板

如

C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE\ItemTemplates\CSharp\Web\MVC 2\CodeTemplates\AddController

         添加控制器时

C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE\ItemTemplates\CSharp\Web\MVC 2\CodeTemplates\AddView

         添加视图时使用，可以在视图中自动基于Model生成必要的代码，减少手工输入，提高效率

下的tt文件都是基于t4进行生成的

校验Validation

服务端

System.ComponentModel.DataAnnotations 下预定义了很多的验证类

如下例

public class CompanyInput

{

    [Required]

    public string CompanyName { get; set; }

 

    [DataType(DataType.EmailAddress)]

    public string EmailAddress { get; set; }

}

控制器处理程序检查ModelState.IsValid确定有效性，如下例

  [HttpPost]

        public ActionResult Edit(CompanyInput input)

        {

            if (ModelState.IsValid)

            {

                return View("Success");

            }

            return View(new CompanyInput());

        }

客户端

Microsft AJAX的方式：

• 首先包含：

    <script src="http://www.cnblogs.com/Scripts/MicrosoftAjax.js" type="text/javascript"></script>

    <script src="http://www.cnblogs.com/Scripts/MicrosoftMvcAjax.js" type="text/javascript"></script>

    <script src="http://www.cnblogs.com/Scripts/MicrosoftMvcValidation.js" type="text/javascript"></script>

• 在需要验证的页面包括：

<% Html.EnableClientValidation(); %>

<h2>Client Validation</h2>

<% Html.EnableClientValidation(); %>                               

<% using (Html.BeginForm("Edit", "Home")) { %>                     

    <%= Html.EditorForModel() %>

    <button type="submit">Submit</button>

<% } %>

The EnableClientValidation method merely turns on a flag in ViewContext. It’s the BeginForm form helper method that emits the pertinent client-side scripts to enable validation. The EnableClientValidation needs to be placed before the BeginForm method in your view to correctly enable scripts.

 In our original screen with company name and email address, the model metadata is emitted as a set of JSON objects. This JSON, shown in figure 15.5, includes the model metadata information, validation information, and model information in the form of a well-structured JSON object. The generated validation information combines with the MVC validation library to act as a bridge between the client-side validation framework and the server-side model metadata emitted as JSON. For example, we can see in figure 15.5 that there seems to be some information about the CompanyName field, as well as a validation message for the required field validation.

大意是Viewer的Helper函数，根据Model的元数据信息生成客户端的验证信息

这个方式有效的把客户端、服务端的验证统一了起来

上例，察看客户端的页面代码可以看到生成的javascript代码

<script type="text/javascript">

//<![CDATA[

if (!window.mvcClientValidationMetadata) { window.mvcClientValidationMetadata = []; }

window.mvcClientValidationMetadata.push({"Fields":[{"FieldName":"CompanyName","ReplaceValidationMessageContents":true,"ValidationMessageId":"CompanyName_validationMessage","ValidationRules":[{"ErrorMessage":"Company Name 字段是必需的。","ValidationParameters":{},"ValidationType":"required"}]},{"FieldName":"EmailAddress","ReplaceValidationMessageContents":true,"ValidationMessageId":"EmailAddress_validationMessage","ValidationRules":[]}],"FormId":"form0","ReplaceValidationSummary":false});

//]]>

</script>