正确的方法来调用嵌套从.NET的OData 4客户端展开（） [英] Proper way to call nested Expand() from .NET OData 4 Client

问题描述

在基于Web API的OData的4个服务，什么是嵌套调用$从.NET客户端扩展的正确方法？我们使用的是的OData客户端生成。早在之前，WCF数据服务的OData 3服务，我们可以称之为 .Expand（客户/订单）。在OData的4网页API，我们不能再这样做，收到你应该尝试以下 .Expand（客户/订单）：

In an OData 4 service on Web API, what is the proper way to call nested $expand from a .NET client? We are using the OData Client Generator. Back in the prior WCF Data Services with OData 3 service we could call .Expand("Customers/Orders"). In Web API with OData 4 we can no longer do so and receive the following should you attempt .Expand("Customers/Orders"):

在URI中指定的查询无效。发现遍历多个导航>属性的路径。请重新表述查询，这样每个扩展路径只包含类型>段和导航属性。

The query specified in the URI is not valid. Found a path traversing multiple navigation >properties. Please rephrase the query such that each expand path contains only type >segments and navigation properties.

我们可以通过调用扩大，像这样以解决此问题： .Expand（客户（$扩大=命令））。在非嵌套$扩大情况下，我喜欢拉姆达支持像这样 .Expand（D =＆GT; d.Customers）。是否有.NET的OData 4客户以适当的方式来调用嵌套扩大无 .Expand不幸魔术字符串（客户（$扩大=命令））？如果没有，是否有像客户/订单，将工作更清洁的字符串模式？谢谢你。

Workaround

We are able to work around this by calling expand like so: .Expand("Customers($expand=Orders)"). In non-nested $expand scenarios, I like the lambda support like so .Expand(d => d.Customers). Is there a proper way in .NET OData 4 client to call nested expands without the unfortunate magic string of .Expand("Customers($expand=Orders)")? If not, is there a cleaner string pattern like "Customers/Orders" that would work? Thanks.

推荐答案

在的OData v4的，它是不是有效扩大多层次的，比如你在问题中提到的内容：.Expand（客户/订单）。我不认为客户会支持这样的API。以下是在ABNF的http://docs.oasis-open.org/odata/odata/v4.0/os/abnf/odata-abnf-construction-rules.txt:

In OData v4, it is not valid to expand multi levels, such as what you mentioned in the question: .Expand("Customers/Orders"). I dont think the client will support such API. Here is what in the ABNF http://docs.oasis-open.org/odata/odata/v4.0/os/abnf/odata-abnf-construction-rules.txt:

expand            = '$expand' EQ expandItem *( COMMA expandItem )
expandItem        = STAR [ ref / OPEN levels CLOSE ]
                  / expandPath
                    [ ref   [ OPEN expandRefOption   *( SEMI expandRefOption   ) CLOSE ]
                    / count [ OPEN expandCountOption *( SEMI expandCountOption ) CLOSE ]
                    /         OPEN expandOption      *( SEMI expandOption      ) CLOSE 
                    ]
expandPath        = [ qualifiedEntityTypeName "/" ] 
                    *( ( complexProperty / complexColProperty ) "/" [ qualifiedComplexTypeName "/" ] )
                    navigationProperty 
                    [ "/" qualifiedEntityTypeName ]

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