装载WCF RIA服务的查询结果，到一个ObservableCollection [英] Loading WCF RIA Services Query results to an ObservableCollection

问题描述

在我的Silverlight应用程序，创建ADO.NET实体数据模型和WCF RIA服务域服务类后，在相应的ProductService I类有一个返回实体产品到客户端的集合，如下查询操作：

In my Silverlight app, after creating ADO.NET Entity Data Model and WCF RIA Services Domain Service Class, in a corresponding ProductService class I have a query operation that returns a collection of Product entities to the client, as follows:

public IQueryable<Product> GetProducts()
{
   return this.ObjectContext.Products;
}

现在我想在客户端Silverlight应用程序和负载结果来阅读到一个ObservableCollection：

Now I'm trying to read it in the client Silverlight app and load results to an ObservableCollection:

ProductContext pcontext = new ProductContext();
ObservableCollection<Prod> prAvs = pcontext.GetProductsQuery();

但得到一个错误：

But getting an error:

无法隐式转换类型 System.ServiceModel.DomainServices.Client.EntityQuery< MyTestApp.Web.Product>
到 System.Collections.ObjectModel.ObservableCollection< ; MyTestApp.Prod>

我怎么能解决这个问题。

How could I fix that issue?

推荐答案

您应该使用客户端产品类通过RIA服务，而不是自己定义的另一个类为您生成。

First problem:

You should be using the client-side Products class generated for you by RIA services, not another class you define yourself.

例如，你应该有MyTestApp.Web.Product的集合，而不是MyTestApp.Prod对象。

e.g you should have a collection of MyTestApp.Web.Product, not of MyTestApp.Prod objects.

你会发现在你的客户端项目在一个隐藏文件夹Generated_Code生成域上下文。 。在这将是包含客户端环境和任何数据对象（如MyTestApp.Web.Product）一个MyTestApp.Web.g.cs文件

You will find the generated domain context in a hidden Generated_Code folder in your client project. Within that will be a MyTestApp.Web.g.cs file containing the client side context and any data objects (like MyTestApp.Web.Product).

您不能只投一个查询到一个集合。

You can't just cast a query to a collection.

您需要使用查询来加载。实体变更集而不是

You need to use the query to load an entity change-set instead.

var loadOperation = pcontext.Load(pcontext.GetProductsQuery());

结果（加载完成时）在返回loadOperation对象实体的集合。您可以立即使用实体集合，但它最初是空的。

The result (when the load completes) is an entity collection in the returned loadOperation object. You can use the entity collection immediately, but it is initially empty.

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