.net - 使用自定义 header 从 Azure 移动服务键入结果

Question

当调用 Azure 移动服务时，我想向自定义 REST 服务发出请求，并将自定义 header 值一起传递并获取键入的结果。为什么我没有这个选项？我错过了什么？

查看https://msdn.microsoft.com/en-us/library/azure/microsoft.windowsazure.mobileservices.mobileserviceclient.invokeapiasync.aspx我只能在发出非类型化请求时提供自定义 header 。

Answer 1

由于对称性，没有添加需要额外 header 的重载:在类型化场景中，您可以为请求指定 header ，但无法读取响应中的 header (因为返回类型是 T 类型，不包含 header 集合)。

但是，您可以使用可传递给 MobileServiceClient 构造函数的消息处理程序来执行此操作的扩展方法。下面的代码是此类实现的示例。它只实现了两个类型化方法，但是如果您想添加其余的方法，那么实现就很简单了。

class Program
{
    public static MobileServiceClient MobileService = new MobileServiceClient(
        "https://YOUR-SERVICE.azure-mobile.net/",
        "YOUR-APPLICATION-KEY"
    );

    static void Main(string[] args)
    {
        DoWork().Wait();
    }

    static async Task DoWork()
    {
        var httpHeaders = new Dictionary<string, string>
        {
            { "x-header-1", "value 1" },
            { "x-header-2", "value 2" },
        };
        var test = await MobileService.InvokeApiWithHeaders<Test>("headers", httpHeaders);
        Console.WriteLine("Returned by the service:");
        foreach (var k in test.AllHeaderValues.Keys)
        {
            Console.WriteLine("  {0}: {1}", k, test.AllHeaderValues[k]);
        }
    }
}

public class Test
{
    public Dictionary<string, string> AllHeaderValues { get; set; }
}

public static class TypedInvokeApiWithHeadersExtensions
{
    public static Task<T> InvokeApiWithHeaders<T>(this MobileServiceClient client, string apiName, IDictionary<string, string> httpHeaders)
    {
        var client2 = new MobileServiceClient(client.ApplicationUri, client.ApplicationKey, new AddHeadersHandler(httpHeaders));
        return client2.InvokeApiAsync<T>(apiName);
    }

    public static Task<T> InvokeApiWithHeaders<T>(this MobileServiceClient client, string apiName, HttpMethod method, IDictionary<string, string> httpHeaders, IDictionary<string, string> queryParameters)
    {
        var client2 = new MobileServiceClient(client.ApplicationUri, client.ApplicationKey, new AddHeadersHandler(httpHeaders));
        return client2.InvokeApiAsync<T>(apiName, method, queryParameters);
    }

    class AddHeadersHandler : DelegatingHandler
    {
        IDictionary<string, string> headers;
        public AddHeadersHandler(IDictionary<string, string> headers)
        {
            this.headers = headers;
        }
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
        {
            foreach (var header in headers)
            {
                request.Headers.TryAddWithoutValidation(header.Key, header.Value);
            }

            return base.SendAsync(request, cancellationToken);
        }
    }
}