XAF-在代码中实现属性值验证（EF）

This lesson explains how to set rules for business classes and their properties. These rules are validated when an end-user executes a specified operation. This lesson will guide you through implementation of a rule that requires that the Position.Title property must not be empty. This rule will be checked when saving a Position object. You will also be able to see the user interface elements that report a broken rule.

本课介绍如何为业务类及其属性设置规则。当最终用户执行指定的操作时，将验证这些规则。本课将指导您完成一个规则的实施，该规则要求位置.Title 属性不能为空。保存"位置"对象时将检查此规则。您还可以看到报告损坏规则的用户界面元素。

Note

Before proceeding, take a moment to review the following lessons.

Inherit from the Business Class Library Class (EF)
Implement Custom Business Classes and Reference Properties (EF)

The validation functionality is provided by the Validation Module. Add this module to your MySolution.Module project. For this purpose, find the Module.cs (Module.vb) file in the MySolution.Module project displayed in the Solution Explorer. Double-click this file to invoke the Module Designer. In the Toolbox, navigate to the DX.19.2: XAF Modules section. Drag the ValidationModule item from this section to the Designer's Required Modules panel. Rebuild your solution.
注意
在继续之前，请花点时间复习以下课程。
从业务类库类（EF）继承
实现自定义业务类和参考属性（EF）
验证功能由验证模块提供。将此模块添加到 MySolution.模块项目中。为此，在解决方案资源管理器中显示的 MySolution.模块项目中查找Module.cs（Module.vb）文件。双击此文件以调用模块设计器。在工具箱中，导航到 DX.19.2：XAF 模块部分。将验证模块项从此部分拖动到"设计器的必需模块"面板。重建解决方案。

In a WinForms application, add the ValidationWindowsFormsModule. This module creates validation error messages that are more informative and user friendly than the default exception messages. Additionally, this module provides in-place validation support (see IModelValidationContext.AllowInplaceValidation). To add this module, find the WinApplication.cs (WinApplication.vb) file in the MySolution.Win project displayed in the Solution Explorer, double-click this file to invoke the Application Designer and drag the ValidationWindowsFormsModule from the Toolbox to the Required Modules panel.

在 WinForms 应用程序中，添加验证窗口窗体模块。此模块创建比默认异常消息更丰富、更友好的验证错误消息。此外，此模块还提供就地验证支持（请参阅 IModel 验证上下文.允许位置验证）。要添加此模块，请在解决方案资源管理器中显示的 MySolution.Win 项目中查找WinApplication.cs （WinApplication.vb）文件，双击此文件以调用应用程序设计器，并将验证Windows窗体模块从工具箱拖动到"必需模块"面板。
In an ASP.NET application, you can also add the ValidationAspNetModule. This module provides in-place validation support (see IModelValidationContext.AllowInplaceValidation). To add this module, find the WebApplication.cs (WebApplication.vb) file in the MySolution.Web project displayed in the Solution Explorer, double-click this file to invoke the Application Designer and drag the ValidationAspNetModule from the Toolbox to the Required Modules panel.
在ASP.NET应用程序中，还可以添加验证AspNet模块。此模块提供就地验证支持（请参阅 IModel 验证上下文.允许位置验证）。要添加此模块，请在解决方案资源管理器中显示的 MySolution.Web 项目中查找WebApplication.cs （WebApplication.vb）文件，双击此文件以调用应用程序设计器，并将验证AspNet模块从工具箱拖动到所需的模块面板。
Apply the RuleRequiredFieldAttribute attribute to the Position class' Title property. As a parameter, specify the context for checking the rule (e.g., DefaultContexts.Save). The RuleRequiredField attribute defines a validation rule that ensures that the Position.Title property has a value when the Position object is saved. The following code demonstrates this attribute.
将"规则所需字段属性"属性应用于职位类的"标题"属性。作为参数，指定用于检查规则的上下文（例如，DefaultContexts.Save）。RuleValuefield 属性定义一个验证规则，以确保在保存"位置"对象时，位置.Title 属性具有值。以下代码演示此属性。
```
using DevExpress.Persistent.Validation;

//...

public class Position {

     //...

    [RuleRequiredField(DefaultContexts.Save)]

    public String Title { get; set; }

}
```
Run the WinForms or ASP.NET application. Click the New () button to create a new Position. Leave the Title property empty and click the Save button. The following error message will be displayed, depending on the application type.
运行 WinForms 或ASP.NET应用程序。单击"新建（button_new）"按钮创建新职位。将"标题"属性留空并单击"保存"按钮。将显示以下错误消息，具体取决于应用程序类型。
WinForms Application
WinForms 应用程序

ASP.NET Application

ASP.NET应用程序

This warning message will also be invoked if you click the Save and Close button, or perform another action that saves the object to the database.
如果单击"保存和关闭"按钮，或执行将对象保存到数据库的另一个操作，也会调用此警告消息。

Note

You can use the Validate toolbar button to check to see if there are broken rules without saving the current object.

注意
您可以使用"验证工具栏"按钮来检查是否有损坏的规则，而无需保存当前对象。
In the WinForms application, close the window with the warning message, set a value for the Title property and click the Save button. In the ASP.NET application, set a value for the Title property and click the Save button. The object will be saved successfully.
在 WinForms 应用程序中，关闭带有警告消息的窗口，为 Title 属性设置值，然后单击"保存"按钮。在ASP.NET应用程序中，为 Title 属性设置值，然后单击"保存"按钮。对象将成功保存。

Note

The Validation System provides a number of Rules and Contexts. For details, refer to the Validation Rules topic. Information on Rules applied in code is loaded into the Application Model (see the Implement Property Value Validation in the Application Model topic). This allows a business application administrator to add and edit Rules and Contexts via the Model Editor.

注意
验证系统提供许多规则和上下文。有关详细信息，请参阅验证规则主题。有关在代码中应用的规则的信息将加载到应用程序模型中（请参阅应用程序模型主题中的实现属性值验证）。这允许业务应用程序管理员通过模型编辑器添加和编辑规则和上下文。

You can see the code demonstrated here in the MySolution.Module | Business Objects | Contact.cs (Contact.vb) file of the EF Demo (Code First) installed with XAF. By default, the EF Demo (Code First) application is installed in %PUBLIC%\Documents\DevExpress Demos 19.2\Components\eXpressApp Framework\EFDemoCodeFirst.

您可以在 MySolution.模块 |业务对象 |Contact.cs（Contact.vb）文件与XAF一起安装的EF演示（代码优先）文件。默认情况下，EF 演示（代码优先）应用程序安装在 %PUBLIC%_文档_DevExpress 演示 19.2_组件_eXpressApp 框架_EFDemoCodeFirst 中。