Wpf MVVM和服务对象

我们目前正在设计一个使用WPF的系统，该系统将使用web服务与其他系统进行通信

我们正在尝试尽可能少的层和映射（通过坚持最简单的方法来降低成本）

我们将使用MVVM模式

所以我们必须有一个视图模型

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问题是，我们可以使用从服务返回的对象作为模型对象，还是应该将这些对象映射到客户端中定义的模型对象？

您不必创建自己的模型层，但是：如果服务发生更改，您必须在引用模型的所有层中反映这些更改。如果现在创建自己的模型层，则会更安全，但工作量会更大。正如经常发生的那样：更多的工作最终会为你节省更多的工作。如果您拥有该服务，并且确信永远不会更改它（哈哈），则不需要模型层

---

当然，这取决于服务检索到的对象是否完全符合您的需要。如果您使用大型对象的1、2个属性，这可能不是一个很好的选择…

是的，您可以使用WCF服务对象作为您的模型层（我们是），尽管如@fantasticfix所说，如果您的WCF服务器对象发生更改，您必须查找引用以修复它们

---

此外，如果要将整个模型公开给视图并绑定到模型的属性，则需要确保WCF服务器对象实现

INotifyPropertyChanged

，而您可以在模型中使用从服务返回的数据对象，有几个原因可以避免这种情况：

您最终可能会在服务数据对象中引入数据绑定需求（、等）

独立地发展服务和WPF应用程序变得更加困难，特别是在服务可能被多个应用程序使用的情况下

您应该考虑使用模型内的服务来封装您的服务通勤作为一个或多个Web服务库。Web服务存储库允许您集中服务的访问逻辑，并为单元测试提供替换点，同时也为您提供了缓存以前服务操作结果的机会

存储库充当不同域中的数据和操作之间的桥梁。存储库向数据源发出适当的查询，然后将结果集映射到业务实体，通常使用模式在表示之间进行转换

您的视图模型将使用服务存储库来检索或持久化信息，存储库将处理对服务的调用，并将数据的服务表示映射到您最终将绑定到的特定于模型的类

您可以更进一步，为服务存储库定义通用接口，使您能够围绕应用程序可能执行的基于CRUD的操作实现特定于服务的存储库

通用服务存储库接口示例：

/// <summary>
/// Describes a service repository that separates the logic that retrieves, persists and maps data to the 
/// domain model from the business logic that acts on the domain model.
/// </summary>
/// <typeparam name="TChannel">The type of channel produced by the channel factory used by the repository.</typeparam>
/// <typeparam name="TMessage">The type of data contract to map to the domain entity of type <typeparamref name="T"/>.</typeparam>
/// <typeparam name="T">The type of domain entity mediated by the repository.</typeparam>
/// <typeparam name="TKey">The type of the key that uniquely identifies domain entities within the repository.</typeparam>
public interface IServiceRepository<TChannel, TMessage, T, TKey> : IRepository<T, TKey> 
  where T : class
{
  /// <summary>
  /// Occurs when the repository transitions from one state to another.
  /// </summary>
  event EventHandler<StateChangedEventArgs> StateChanged;

  /// <summary>
  /// Gets the configuration name used for the service endpoint.
  /// </summary>
  /// <value>
  /// The name of the endpoint in the application configuration file that is used 
  /// to create a channel to the service endpoint.
  /// </value>
  string EndpointConfigurationName
  {
      get;
  }

  /// <summary>
  /// Gets the current state of the service repository.
  /// </summary>
  /// <value>
  /// The current <see cref="CommunicationState"/> of the service repository.
  /// </value>
  CommunicationState State
  {
      get;
  }
}

/// <summary>
/// Describes a repository that separates the logic that retrieves, persists and maps data to the domain model 
/// from the business logic that acts on the domain model.
/// </summary>
/// <typeparam name="T">The type of domain entity mediated by the repository.</typeparam>
/// <typeparam name="TKey">The type of the key that uniquely identifies domain entities within the repository.</typeparam>
public interface IRepository<T, TKey> 
  where T : class
{
  /// <summary>
  /// Occurs when a repository action has been completed.
  /// </summary>
  event EventHandler<RepositoryActionCompletedEventArgs<T>> Completed;

  /// <summary>
  /// Occurs when a repository action fails to execute.
  /// </summary>
  event EventHandler<RepositoryActionFailedEventArgs<T>> Failed;

  /// <summary>
  /// Gets a value indicating if the repository has been disposed of.
  /// </summary>
  /// <value>
  /// <see langword="true" /> if the repository has been disposed of; otherwise, <see langword="false" />.
  /// </value>
  bool IsDisposed
  {
      get;
  }

  /// <summary>
  /// Adds a new <paramref name="entity"/> to the data source layer.
  /// </summary>
  /// <param name="entity">The entity of type <typeparamref name="T"/> to insert into the data source layer.</param>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after the <paramref name="entity"/> is insert into the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  /// <exception cref="ArgumentNullException">The <paramref name="entity"/> is a <see langword="null"/> reference (Nothing in Visual Basic).</exception>
  IRepository<T, TKey> Add(T entity, Action<T, Exception> callback = null);

  /// <summary>
  /// Retrieves all entities of type <typeparamref name="T"/> from the data source layer.
  /// </summary>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after all entities of type <typeparamref name="T"/> are retrieved from the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  IRepository<T, TKey> Get(Action<IEnumerable<T>, Exception> callback = null);

  /// <summary>
  /// Retrieves an entity of type <typeparamref name="T"/> from the data source layer that 
  /// matches the specified <paramref name="key"/>.
  /// </summary>
  /// <param name="key">The unique identifier of the entity of type <typeparamref name="T"/> to retrieve from the data source layer.</param>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after an entity of type <typeparamref name="T"/> that matches the specified <paramref name="key"/> is retrieved from the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  IRepository<T, TKey> Get(TKey key, Action<T, Exception> callback = null);

  /// <summary>
  /// Removes an existing <paramref name="entity"/> from the data source layer.
  /// </summary>
  /// <param name="entity">An entity of type <typeparamref name="T"/> to delete from the data source layer.</param>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after the <paramref name="entity"/> is removed from the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  /// <exception cref="ArgumentNullException">The <paramref name="entity"/> is a <see langword="null"/> reference (Nothing in Visual Basic).</exception>
  IRepository<T, TKey> Remove(T entity, Action<T, Exception> callback = null);

  /// <summary>
  /// Updates an existing <paramref name="entity"/> within the data source layer.
  /// </summary>
  /// <param name="entity">The entity of type <typeparamref name="T"/> to update within the data source layer.</param>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after the <paramref name="entity"/> is updated within the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  /// <exception cref="ArgumentNullException">The <paramref name="entity"/> is a <see langword="null"/> reference (Nothing in Visual Basic).</exception>
  IRepository<T, TKey> Update(T entity, Action<T, Exception> callback = null);
}

//
///描述一个服务存储库，该存储库分离用于检索、持久化数据并将数据映射到
///来自作用于域模型的业务逻辑的域模型。
/// 
///存储库使用的通道工厂生成的通道类型。
///要映射到类型为的域实体的数据协定类型。
///存储库介导的域实体的类型。
///唯一标识存储库中的域实体的密钥类型。
公共接口IServiceRepository:IRepository
T:在哪里上课
{
/// 
///当存储库从一种状态转换到另一种状态时发生。
/// 
事件处理程序状态已更改；
/// 
///获取用于服务端点的配置名称。
/// 
/// 
///所使用的应用程序配置文件中端点的名称
///创建到服务端点的通道。
/// 
字符串EndpointConfigurationName
{
得到；
}
/// 
///获取服务存储库的当前状态。
/// 
/// 
///服务存储库的当前名称。
/// 
通讯状态
{
得到；
}
}

通用存储库接口示例：

/// <summary>
/// Describes a service repository that separates the logic that retrieves, persists and maps data to the 
/// domain model from the business logic that acts on the domain model.
/// </summary>
/// <typeparam name="TChannel">The type of channel produced by the channel factory used by the repository.</typeparam>
/// <typeparam name="TMessage">The type of data contract to map to the domain entity of type <typeparamref name="T"/>.</typeparam>
/// <typeparam name="T">The type of domain entity mediated by the repository.</typeparam>
/// <typeparam name="TKey">The type of the key that uniquely identifies domain entities within the repository.</typeparam>
public interface IServiceRepository<TChannel, TMessage, T, TKey> : IRepository<T, TKey> 
  where T : class
{
  /// <summary>
  /// Occurs when the repository transitions from one state to another.
  /// </summary>
  event EventHandler<StateChangedEventArgs> StateChanged;

  /// <summary>
  /// Gets the configuration name used for the service endpoint.
  /// </summary>
  /// <value>
  /// The name of the endpoint in the application configuration file that is used 
  /// to create a channel to the service endpoint.
  /// </value>
  string EndpointConfigurationName
  {
      get;
  }

  /// <summary>
  /// Gets the current state of the service repository.
  /// </summary>
  /// <value>
  /// The current <see cref="CommunicationState"/> of the service repository.
  /// </value>
  CommunicationState State
  {
      get;
  }
}

/// <summary>
/// Describes a repository that separates the logic that retrieves, persists and maps data to the domain model 
/// from the business logic that acts on the domain model.
/// </summary>
/// <typeparam name="T">The type of domain entity mediated by the repository.</typeparam>
/// <typeparam name="TKey">The type of the key that uniquely identifies domain entities within the repository.</typeparam>
public interface IRepository<T, TKey> 
  where T : class
{
  /// <summary>
  /// Occurs when a repository action has been completed.
  /// </summary>
  event EventHandler<RepositoryActionCompletedEventArgs<T>> Completed;

  /// <summary>
  /// Occurs when a repository action fails to execute.
  /// </summary>
  event EventHandler<RepositoryActionFailedEventArgs<T>> Failed;

  /// <summary>
  /// Gets a value indicating if the repository has been disposed of.
  /// </summary>
  /// <value>
  /// <see langword="true" /> if the repository has been disposed of; otherwise, <see langword="false" />.
  /// </value>
  bool IsDisposed
  {
      get;
  }

  /// <summary>
  /// Adds a new <paramref name="entity"/> to the data source layer.
  /// </summary>
  /// <param name="entity">The entity of type <typeparamref name="T"/> to insert into the data source layer.</param>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after the <paramref name="entity"/> is insert into the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  /// <exception cref="ArgumentNullException">The <paramref name="entity"/> is a <see langword="null"/> reference (Nothing in Visual Basic).</exception>
  IRepository<T, TKey> Add(T entity, Action<T, Exception> callback = null);

  /// <summary>
  /// Retrieves all entities of type <typeparamref name="T"/> from the data source layer.
  /// </summary>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after all entities of type <typeparamref name="T"/> are retrieved from the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  IRepository<T, TKey> Get(Action<IEnumerable<T>, Exception> callback = null);

  /// <summary>
  /// Retrieves an entity of type <typeparamref name="T"/> from the data source layer that 
  /// matches the specified <paramref name="key"/>.
  /// </summary>
  /// <param name="key">The unique identifier of the entity of type <typeparamref name="T"/> to retrieve from the data source layer.</param>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after an entity of type <typeparamref name="T"/> that matches the specified <paramref name="key"/> is retrieved from the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  IRepository<T, TKey> Get(TKey key, Action<T, Exception> callback = null);

  /// <summary>
  /// Removes an existing <paramref name="entity"/> from the data source layer.
  /// </summary>
  /// <param name="entity">An entity of type <typeparamref name="T"/> to delete from the data source layer.</param>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after the <paramref name="entity"/> is removed from the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  /// <exception cref="ArgumentNullException">The <paramref name="entity"/> is a <see langword="null"/> reference (Nothing in Visual Basic).</exception>
  IRepository<T, TKey> Remove(T entity, Action<T, Exception> callback = null);

  /// <summary>
  /// Updates an existing <paramref name="entity"/> within the data source layer.
  /// </summary>
  /// <param name="entity">The entity of type <typeparamref name="T"/> to update within the data source layer.</param>
  /// <param name="callback">
  /// The optional <see langword="delegate"/> method that will be executed after the <paramref name="entity"/> is updated within the data source layer.
  /// </param>
  /// <returns>
  /// The <see cref="IRepository{T, Tkey}"/> object that this method was called on.
  /// </returns>
  /// <exception cref="ArgumentNullException">The <paramref name="entity"/> is a <see langword="null"/> reference (Nothing in Visual Basic).</exception>
  IRepository<T, TKey> Update(T entity, Action<T, Exception> callback = null);
}

//
///描述一个存储库，该存储库分离用于检索、持久化数据并将数据映射到域模型的逻辑
///从作用于域模型的业务逻辑。
/// 
///存储库介导的域实体的类型。
///唯一标识存储库中的域实体的密钥类型。
公共接口假定
T:在哪里上课
{
/// 
///在存储库操作完成时发生。
/// 
事件处理程序已完成；
/// 
///当存储库操作无法执行时发生。
/// 
事件处理程序失败；
/// 
///获取一个值，该值指示存储库是否已被释放。
/// 
/// 
///如果存储库已被处置，则为。
/// 
布勒被揭穿了
{
得到；
}
/// 
///向数据源层添加新的。
/// 
///要插入到数据源层中的类型的实体。
/// 
///将插入数据源层后将执行的可选方法。
/// 
/// 
///调用此方法的对象。
/// 
///是一个引用（在Visual Basic中没有）。
i正向添加（T实体，动作回调=null）；
/// 
///从数据源层检索类型为的所有实体。
/// 
/// 
///从数据源层检索所有类型的实体后将执行的可选方法。
/// 
/// 
///调用此方法的对象。
/// 
IRepository Get（操作回调=null）；
/// 
///从要删除的数据源层检索类型为的实体
///匹配指定的。
/// 
///实体o的唯一标识符