How to: Initialize an Object Created Using the New Action 如何:初始化使用新按钮创建的对象

This topic describes how to access an object that is created using the New Action. Assume you are using the Task business class from the Business Class Library. When creating a new Task using the New Action, the Task.StartDate property will be set to the current date.

本主题介绍如何访问使用"新建"按钮创建的对象。假设您正在使用业务类库中的 Task 业务类。使用"新建"按钮创建新任务时，"Task.StartDate"属性将设置为当前日期。

Note 注意

The approach described in this topic is not supported by the Mobile platform. If it is necessary to implement this scenario in your Mobile application, contact us using the Support Center

移动平台不支持本主题中描述的方法。如果需要在移动应用程序中实施此方案，请使用支持中心与我们联系

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Tip 提示

A complete sample project is available in the DevExpress Code Examples database at http://www.devexpress.com/example=E229

完整的示例项目可在 DevExpress 代码示例数据库中找到，http://www.devexpress.com/example=E229

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To access an object created using the New Action, handle the NewObjectViewController.ObjectCreated event of the NewObjectViewController that contains the New Action. To do this, implement a new View Controller. Override the Controller's OnActivated method and subscribe to the ObjectCreated event in the following manner:

要访问使用"新建操作"创建的对象，请使用"新建对象视图控制器.对象创建"事件处理包含"新建操作"的 NewObjectViewController。为此，实现一个新的视图控制器。重写控制器的 On 已激活方法，然后以下列方式订阅 ObjectCreated 事件：

using DevExpress.Persistent.BaseImpl;
using DevExpress.ExpressApp.SystemModule;
//...
public class MyController : ViewController {
    private NewObjectViewController controller;
    protected override void  OnActivated() {
        base.OnActivated();
        controller = Frame.GetController<NewObjectViewController>();
        if (controller != null) {
            controller.ObjectCreated += controller_ObjectCreated;
        }
    }
    void controller_ObjectCreated(object sender, ObjectCreatedEventArgs e) {
        if (e.CreatedObject is Task) {
            ((Task)e.CreatedObject).StartDate = DateTime.Now;
        }
    }
    protected override void OnDeactivated() {
        if (controller != null) {
            controller.ObjectCreated -= controller_ObjectCreated;
        }
        base.OnDeactivated();
    }
}

In certain scenarios, it can be required to initialize a new object created through the lookup editor's New button, using a value from the parent Detail View. To access the parent object from the ObjectCreated event handler, cast the Controller.Frame value to the NestedFrame type, access the NestedFrame.ViewItem property and then get the master object using the ViewItem.CurrentObject property.

在某些情况下，可能需要使用父详细信息视图中的值初始化通过查找编辑器的"新建"按钮创建的新对象。要从 Object创建事件处理程序访问父对象，将控制器.Frame 值转换为嵌套帧类型，访问 NestedFrame.ViewItem 属性，然后使用 ViewItem.CurrentObject 属性获取主对象。

void controller_ObjectCreated(object sender, ObjectCreatedEventArgs e) {
    NestedFrame nestedFrame = Frame as NestedFrame;
    if (nestedFrame != null) {
        Item createdItem = e.CreatedObject as Item;
        if (createdItem != null) {
            Parent parent = ((NestedFrame)Frame).ViewItem.CurrentObject as Parent;
            if (parent != null) {
                createdItem.Title = parent.DefaultItemTitle;
            }
        }
    }
}