使用WCF RIA服务进行动态查询 [英] Dynamic query with WCF RIA Services

问题描述

我将Silverlight 4与WCF RIA服务(带EF4的域服务)一起使用.现在，我想添加一个功能，该功能允许用户根据用户选择的条件查询数据(临时查询).我发现:

I use Silverlight 4 with WCF RIA Services (domain services with EF4). Now I'd like to add a functionality, which allow an user to query data based on the criteria user selected (ad-hoc query). I've found that:

-WCF RIA服务不允许匿名类型，因此无法进行linq投影.

-WCF RIA Services doesn't allow anonymous types, so linq projection isn't possible.

-公开OData没有多大帮助，因为您不能在客户端过滤数据.

-Exposing OData doesn't help (much), because you can't filter data at client-side.

搜索Internet时，似乎可以使用以下链接中描述的动态linq库:

Searching Internet, it seems I can use dynamic linq library described in the following link:

http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx

简而言之，以上链接显示了如何将搜索谓词传递给服务器，以及如何在服务器端执行查询. 但是如何返回任意数据呢?匿名类型无法传递，我不希望用户检索所有数据，而只能检索用户选择的那些字段.也许我应该在域服务中序列化我的实体数据，并将其作为原始xml传递?是否有可能?如果是这样，我该怎么办?

In short, the above link shows how to pass search predicate to server, and execute query at the server-side. But how about returning arbitrary data? Anonymous types can't be passed, and I don't want user to retrieve all data, but only those fields user chose. Maybe I should serialize my entity data in domain service and pass it as raw xml? Is it possible? If so, how can I do that?

推荐答案

对于我们的一种情况，我们有一个DomainService操作，该操作返回xml字符串，它看起来像这样:

For one of our scenarios we have a DomainService operation which returns xml strings, it looks something like this:

public IQueryable<WidgetInfo> GetWidgetList()
{
    IList<WidgetInfo> widgets = WidgetDatabase.GetWidgets(userId);
    return widgets.AsQueryable();
}

其中WidgetInfo看起来像这样:

public class WidgetInfo
{
    [Key]
    public int Id;
    public string Title;
    public string WidgetData;   // Contains XML description of data
}

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