Web Api 2处理选项请求 [英] Web Api 2 Handle OPTIONS Requests

问题描述

我在Azure和 AngularJs forntend上托管了 Web Api 2 后端.我了解到某些 HTTP请求与 OPTIONS请求一起使用了预检查.我的问题是如何以这种方式实现后端，如果控制器中有一些动作可以处理以下 GET/POST/PUT/DELETE/... <，那么所有 OPTIONS请求都将返回200./code>.

I have Web Api 2 backend hosted on Azure and AngularJs forntend. I understand that some of HTTP request use pre-check with OPTIONS request. My question is how to implement backend that way, that all OPTIONS requests will return 200 if there is some action in controller that will handle following GET/POST/PUT/DELETE/....

推荐答案

解决此问题的一种非优雅方法是手动在每个控制器中添加

Non elegant way to solve this task is adding in each controller manually

[AcceptVerbs("OPTIONS")]
public HttpResponseMessage Options()
{
    var resp = new HttpResponseMessage(HttpStatusCode.OK);
    resp.Headers.Add("Access-Control-Allow-Origin", "*");
    resp.Headers.Add("Access-Control-Allow-Methods", "GET,DELETE");

    return resp;
}

或覆盖MessageHandlers

 public class OptionsHttpMessageHandler : DelegatingHandler
{
  protected override Task<HttpResponseMessage> SendAsync(
  HttpRequestMessage request, CancellationToken cancellationToken)
  {
    if (request.Method == HttpMethod.Options)
      {
         var apiExplorer = GlobalConfiguration.Configuration.Services.GetApiExplorer();

          var controllerRequested = request.GetRouteData().Values["controller"] as string;              
          var supportedMethods = apiExplorer.ApiDescriptions.Where(d => 
             {  
                var controller = d.ActionDescriptor.ControllerDescriptor.ControllerName;
                return string.Equals(
                    controller, controllerRequested, StringComparison.OrdinalIgnoreCase);
            })
          .Select(d => d.HttpMethod.Method)
          .Distinct();

      if (!supportedMethods.Any())
         return Task.Factory.StartNew(
             () => request.CreateResponse(HttpStatusCode.NotFound));

      return Task.Factory.StartNew(() =>
        {
            var resp = new HttpResponseMessage(HttpStatusCode.OK);
            resp.Headers.Add("Access-Control-Allow-Origin", "*");
            resp.Headers.Add(
                "Access-Control-Allow-Methods", string.Join(",", supportedMethods));

            return resp;
        });
}

return base.SendAsync(request, cancellationToken);

  }
}

，然后在配置中

GlobalConfiguration.Configuration.MessageHandlers.Add(new OptionsHttpMessageHandler());

第二个选项虽然不完美，但没有本机版本支持

even second option is not perfect though... no native build in support

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