6

假设我正在使用新的 WCF Web API 来构建一个 RESTful 服务，并且在我的服务中，我有一段 URI 将描述目标资源，但用于（几乎）合同的所有方法。例如，如果我有一个处理电子商务的用户服务，它可能看起来像：

[ServiceContract]
public class MyUserService
{
    private MyUserRepository _UserRepo;
    private MyOrganizationRepository _OrgRepo;

    [WebGet (UriTemplate = "{OrganizationName}/Users")]
    public IEnumerable<User> GetUsers (string OrganizationName)
    {
        IEnumerable<User> Users = null;
        var Organization = _OrgRepo.GetOrgByName (OrganizationName);

        if (Organization != null)
        {
            Users = Organization.GetUsers ();
        }
        else
        {
            throw new WebFaultException<string> ("Organization not found.", HttpStatusCode.NotFound);
        }

        return Users;
    }

    [WebInvoke (UriTemplate = "{OrganizationName}/Users", /*yada...yada...yada*/)]
    public User AddNewUser (string OrganizationName, User User)
    {
        // Find the organization, like above, and throw if null.
    }
}

如果我必须不断地加载组织并测试 null，这将使我的代码陷入困境并且不是很干燥。（所以很想拼出 DRY ...）我想做的是在 MyUserService 类中加载一个属性，当 {OrganizationName} 包含在 URI 中时填充该属性，否则抛出 WebFaultException。因为这是 URI 的一部分，所以最好的方法是什么？

编辑：

对于那些可能感兴趣的人，这里是我想出的 HttpOperationHandler 的示例。似乎没有很多信息可以涵盖这一点。我还发现了有关 WCF Web Api 套件将附带的处理器的更多信息，看起来他们会更好地处理这类事情，取代 HttpOperationHandlers 并且看起来它们可能更容易使用。（这只是为了涵盖一些我发现很难找到的东西。我在我的应用程序中写的有点不同。）

using Microsoft.ApplicationServer.Http.Dispatcher;   // For HttpOperationHandler
using Microsoft.ApplicationServer.Http.Description;  // For HttpOperationHandlerFactory

public class OrganizationHandler : HttpOperationHandler<string, Organization>
{
    private Repository<Organization> _OrganizationRepository;

    public OrganizationHandler (UnitOfWork Work)
        : base ("OrganizationName")
    {
        _OrganizationRepository = Work.Organizations;
    }

    public override Organization OnHandle (string OrganizationName)
    {
        var Result = _OrganizationRepository
                        .Get (O => O.UrlSafeName.Equals (OrganizationName,
                                                StringComparison.InvariantCultureIgnoreCase));

        if (Result == null)
        {
            throw new WebFaultException<string> ("Organization not found.");
        }

        return Result;
    }
}

public class OrganizationHandlerFactory : HttpOperationHandlerFactory
{
    private UnitOfWork _Work;

    public OrganizationHandlerFactory (UnitOfWork Work)
    {
        _Work = Work;
    }

    protected override Collection<HttpOperationHandler> OnCreateRequestHandlers
        (ServiceEndpoint endpoint, HttpOperationDescription operation)
    {
        var Collection = base.OnCreateRequestHandlers (endpoint, operation);

        if (operation.InputParameters.Any (IP => IP.Type.Equals (typeof (Organization))))
        {
            var Binding = endpoint.Binding as HttpBinding;

            if (Binding != null)
            {
                Collection.Add (new OrganizationHandler (_Work));
            }
        }

        return Collection;
    }
}

然后在 Global.asax 中连接它（我使用 Ninject 进行 IoC）：

// Add this reference to get the MapServiceRoute<T> extension
using Microsoft.ApplicationServer.Http.Activation;

public class Global : HttpApplication
{
    protected void Application_Start (object sender, EventArgs e)
    {
        var Kernel = BuildKernel ();

        var Config = HttpHostConfiguration.Create ()
            .SetOperationHandlerFactory
                (Kernel.Get (typeof (OrganizationHandlerFactory)) as OrganizationHandlerFactory)
            .SetResourceFactory (new NinjectResourceFactory (Kernel));


        RouteTable.Routes.MapServiceRoute<OrganizationService> ("Organizations", Config);
    }

    protected IKernel BuildKernel ()
    {
        IKernel Kernel = new Ninject.StandardKernel ();

        // Load up the Kernel

        return Kernel;
    }
}

public class NinjectResourceFactory : IResourceFactory
{
    private readonly IKernel _Kernel;

    public NinjectResourceFactory (IKernel Kernel)
    {
        _Kernel = Kernel;
    }

    public object GetInstance (Type serviceType, InstanceContext instanceContext, HttpRequestMessage request)
    {
        return Resolve (serviceType);
    }

    public void ReleaseInstance (InstanceContext instanceContext, object service)
    {
        throw new NotImplementedException ();
    }

    private object Resolve (Type type)
    {
        return _Kernel.Get (type);
    }
}

它在我的服务中：

[ServiceContract]
[ServiceBehavior (InstanceContextMode = InstanceContextMode.PerCall)]
public class OrganizationService
{
    [WebGet (UriTemplate = "{OrganizationName}/Products")]
    public IEnumerable<Product> GetProducts (Organization Organization)
    {
        return Organization.Products;
    }
}
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1 回答 1

2

这正是 OperationHandlers 的用途。您创建了一个 OperationHandler，它将 URI 参数转换为一个强类型对象，您可以将其作为操作的参数接受。

于 2011-05-20T01:36:48.490 回答