c# - 使用相同的方法进行 PUT 和 POST

Question

我正在开发一个 WCF Rest 服务，我的 ServiceContract 上有这个:

    [OperationContract]
    [WebInvoke(Method = "POST",
        UriTemplate = "/users",
        RequestFormat = WebMessageFormat.Json,
        ResponseFormat = WebMessageFormat.Json,
        BodyStyle = WebMessageBodyStyle.Bare)]
    User AddOrUpdateUser(User user);

    [OperationContract]
    [WebInvoke(Method = "PUT",
        UriTemplate = "/users",
        RequestFormat = WebMessageFormat.Json,
        ResponseFormat = WebMessageFormat.Json,
        BodyStyle = WebMessageBodyStyle.Bare)]
    User AddOrUpdateUser(User user);

我将使用 User AddOrUpdateUser(User user); 进行 POST 和 PUT:

    public User AddOrUpdateUser(User user)
    {
        if (user == null)
            throw new ArgumentNullException("user", "AddOrUpdateUser: user is null");

        using (var context = new AdnLineContext())
        {
            context.Entry(user).State = user.UserId == 0 ?
                                        EntityState.Added :
                                        EntityState.Modified;
            context.SaveChanges();
        }

        return user;
    }

我正在关注这个 pattern去做。

但是，我得到一个错误:

The type 'MyCompanyWCFService.IMyCompanyService' already contains a definition for 
'AddOrUpdateUser' with the same parameters

我该如何解决这个问题？

Answer 1

您不能有两个具有相同签名的方法 - 这是 C# 问题，而不是 WCF 问题。你基本上有两种选择去这里。第一种是有两个不同的方法，一个调用另一个，或者有第三个方法由两者调用):

public interface ITest
{
    [OperationContract]
    [WebInvoke(Method = "POST",
        UriTemplate = "/users",
        RequestFormat = WebMessageFormat.Json,
        ResponseFormat = WebMessageFormat.Json,
        BodyStyle = WebMessageBodyStyle.Bare)]
    User AddUser(User user);

    [OperationContract]
    [WebInvoke(Method = "PUT",
        UriTemplate = "/users",
        RequestFormat = WebMessageFormat.Json,
        ResponseFormat = WebMessageFormat.Json,
        BodyStyle = WebMessageBodyStyle.Bare)]
    User UpdateUser(User user);
}

和实现:

public class Service
{
    public User AddUser(User user) { return AddOrUpdateUser(user); }
    public User UpdateUser(User user) { return AddOrUpdateUser(user); }
    private User AddOrUpdateUser(User user)
    {
        if (user == null)
            throw new ArgumentNullException("user", "AddOrUpdateUser: user is null");

        using (var context = new AdnLineContext())
        {
            context.Entry(user).State = user.UserId == 0 ?
                                        EntityState.Added :
                                        EntityState.Modified;
            context.SaveChanges();
        }

        return user;
    }
}

另一种选择是使用一个方法接受多个 HTTP 方法；您可以通过在 WebInvoke 属性上指定 Method = "*" 来做到这一点。但是如果你走那条路线，你应该在操作中验证传入的 HTTP 动词是你期望的动词之一:

public interface ITest
{
    [OperationContract]
    [WebInvoke(Method = "*",
        UriTemplate = "/users",
        RequestFormat = WebMessageFormat.Json,
        ResponseFormat = WebMessageFormat.Json,
        BodyStyle = WebMessageBodyStyle.Bare)]
    User AddOrUpdateUser(User user);
}

和实现:

public class Service
{
    public User AddOrUpdateUser(User user)
    {
        var method = WebOperationContext.Current.IncomingRequest.Method.ToUpperInvariant();
        if (method != "POST" || method != "PUT")
        {
            throw new WebFaultException(HttpStatusCode.MethodNotAllowed);
        }

        if (user == null)
            throw new ArgumentNullException("user", "AddOrUpdateUser: user is null");

        using (var context = new AdnLineContext())
        {
            context.Entry(user).State = user.UserId == 0 ?
                                        EntityState.Added :
                                        EntityState.Modified;
            context.SaveChanges();
        }

        return user;
    }
}