周转基金。 服务通用方法

Question

How can I use generic methods in wcf service?

I wrote this code:

[OperationContract]
void AddItem<T>(T item);

But I receive the following Error:

Type 'T' cannot be exported as a schema type because it is an open generic type. You can only export a generic type if all its generic parameter types are actual types.

Answer 1

You simply can't. It's not possible to do that, as soap does not support this. See this article , which mentions how to get around generics, by creating an intermediate local object that is called and casts the object before calling the WCF operation.

Answer 2

You shouldn't be trying to do this. In a SOAP enabled web service all types need to be known when the WSDL is published so that clients would be capable of generating a proxy. Generics simply don't exist in the SOAP specification. SOAP is intended to be interoperable and generics don't exist in all languages.

Answer 3

可以使用数据契约中的有界泛型类型，但必须是服务契约中指定的类型参数，并作为具有有效数据契约的指定类型参数

Answer 4

As all the others have already mentioned, WCF and SOAP do not support this. The issue is: anything you pass back and forth between client and server must be expressible in a XML schema document.

XML schema supports all the usual atomic types, like string, int, datetime - and it supports complex types made up of those atomic types, and it supports inheritance.

But XML schema has no support for generics - and thus, anything you exchange via WCF and SOAP cannot be generic - you need to use concrete, non-generic types only.

I don't know of any way around this, either. It's a limitation and you have to live with it for now.

Answer 5

The error says that open types are not allowed. What probably is allowed is something like:

[OperationContract]
void AddItem<T>(T item) where T : MyBaseType;

Ofcourse, all inherited types should be added with the KnownType attribute.