资源未找到段“财产” [英] Resource not found for segment 'Property'

问题描述

在使用ADO.Net数据服务客户端通过调用LoadProperty刷新实体：

When using ADO.Net Data Services client to refresh an entity by calling the LoadProperty:

ctx.BeginLoadProperty(this, "Owner", (IAsyncResult ar) => ...

它抛出一个错误的服务器上如果属性为null。

It throws an error on the server if the property is null

Error: Exception Thrown: System.Data.Services.DataServiceException: Resource not found for the segment 'Owner'.
   at System.Data.Services.RequestDescription.GetSingleResultFromEnumerable(SegmentInfo segmentInfo)
   at System.Data.Services.DataService`1.CompareETagAndWriteResponse(RequestDescription description, ContentFormat responseFormat, IDataService dataService)
   at System.Data.Services.DataService`1.SerializeResponseBody(RequestDescription description, IDataService dataService)
   at System.Data.Services.DataService`1.HandleNonBatchRequest(RequestDescription description)
   at System.Data.Services.DataService`1.HandleRequest()

问题是，客户端不知道该属性是否为空或只是尚未填充。业主是从车辆到客户的链接。

Problem is that the client does not know whether the property is null or just hasn't been populated yet. The property Owner is a link from a Vehicle to a Customer.

任何想法有什么不对？

感谢

推荐答案

查询主键生成当键不存在异常。解决方法是在条件中添加一个虚拟的真实表达。（如：1 == 1安培;&安培; item.Id == XXX）

Querying on primary keys generate an exception when the key does not exist. The workaround is to add a dummy true expression in the condition (eg : 1==1 && item.Id == XXX).

如果没有虚拟表达ADO.NET的要求是：

Without the dummy expression the ADO.NET request is:

HTTP：//localhost//test.svc/Role(XXX）

http: //localhost//test.svc/Role(XXX)

通过虚拟条件下，要求是：

With the dummy condition, the request is:

HTTP： //localhost//test.svc/Role()?$filter=true和（同上EQ 1）

http: //localhost//test.svc/Role()?$filter=true and (Id eq 1)

预期的行为（空返回）是在第二种情况下是正确的。

The expected behaviour (null returned) is correct in the second case.

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