满足子视图模型依赖关系

发布于 2024-09-11 20:21:29 字数 149 浏览 4 评论 0原文

我正在构建一个主从表单。主视图模型构造细节视图模型的实例。这些细节视图模型有几个依赖项，需要用新类实例来满足。（这是因为它们需要在与主虚拟机不同的数据上下文中运行的服务层。）

满足这些依赖关系的最佳方法是什么？

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烟─花易冷 2024-09-18 20:21:29

WPF 应用程序框架 (WAF)BookLibrary 示例应用程序strong> 展示了如何使用 MV-VM 实现主/细节场景。它使用 MEF 作为 IoC 容器来满足 ViewModel 依赖关系。

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伴梦长久 2024-09-18 20:21:29

您还可以使用容器构建详细视图：

var detailViewModel = container.CreateInstance<DetailViewModel>();

容器将解析 IAccountService 和 ITransactionService 的依赖关系。但您仍然依赖 IOC 框架（除非您使用 CommonServiceLocator）。

以下是我使用 CommonServiceLocator 执行此操作的方法：

this.accountService = ServiceLocator.Current.GetInstance<IAccountService>();
this.transactionService = ServiceLocator.Current.GetInstancey<ITransactionService>();

You can also use the container to construct the detail view:

var detailViewModel = container.CreateInstance<DetailViewModel>();

The container will resolve the dependencies for IAccountService and ITransactionService. But you will still have a dependency on the IOC framework (unless you use the CommonServiceLocator).

Here is how I do it using the CommonServiceLocator:

this.accountService = ServiceLocator.Current.GetInstance<IAccountService>();
this.transactionService = ServiceLocator.Current.GetInstancey<ITransactionService>();

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我不在是我 2024-09-18 20:21:29

一些可能性：

硬编码引用

以下方法可以解决该问题。然而，由于它引入了硬编码的依赖关系，因此使用它是不可能的。

// in the master view model
var detailViewModel = new DetailViewModel(new AccountService(), new TransactionService());

通过 IoC 框架解决

另一个选择是让父视图模型保存对 IoC 框架的引用。这种方法引入了对 IoC 框架的主视图模型依赖。

// in the master view model
var detailViewModel = new DetailViewModel(resolver.GetNew<IAccountService>(), resolver.GetNew<IAccountService>());

工厂函数

class MasterViewModel {
  public MasterViewModel(Func<Service.IAccountService> accountServiceFactory, Func<Service.ITransactionService> transactionServiceFactory) {
    this.accountServiceFactory = accountServiceFactory;
    this.transactionServiceFactory = transactionServiceFactory;

    // instances for MasterViewModel's internal use
    this.accountService = this.accountServiceFactory();
    this.transactionService = this.transactionServiceFactory():
  }
  public SelectedItem { 
    set {
       selectedItem = value;
       DetailToEdit = new DetailViewModel(selectedItem.Id, accountServiceFactory(), transactionServiceFactory());
    }
    // ....

Some Possibilities:

Hard-Coded References

The following approach would solve the problem. However, as it introduces hard-coded dependencies, using it is out of the question.

// in the master view model
var detailViewModel = new DetailViewModel(new AccountService(), new TransactionService());

Resolution via IoC Framework

Another option would be for the parent view model to hold a reference to an IoC framework. This approach introduces a master view model dependency on the IoC framewok.

// in the master view model
var detailViewModel = new DetailViewModel(resolver.GetNew<IAccountService>(), resolver.GetNew<IAccountService>());

Factory Func<>s

class MasterViewModel {
  public MasterViewModel(Func<Service.IAccountService> accountServiceFactory, Func<Service.ITransactionService> transactionServiceFactory) {
    this.accountServiceFactory = accountServiceFactory;
    this.transactionServiceFactory = transactionServiceFactory;

    // instances for MasterViewModel's internal use
    this.accountService = this.accountServiceFactory();
    this.transactionService = this.transactionServiceFactory():
  }
  public SelectedItem { 
    set {
       selectedItem = value;
       DetailToEdit = new DetailViewModel(selectedItem.Id, accountServiceFactory(), transactionServiceFactory());
    }
    // ....

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