'ObjectContent`1'类型无法为内容类型'application / json'

Question

我正在使用带WebApi的asp.net MVC。在localhost上一切正常，但在appharbor部署的网站上，每次调用webapi控制器时都会遇到异常The 'ObjectContent 1 type failed to serialize the response body for content type 'application/json; charset=utf-8'。

我的webapi功能是：

public async Task<IHttpActionResult> GetMobileTrends()
        {
            var ret = (from ad in db.MobileAds
                      orderby ad.Ad.views
                      where ad.Ad.AdImages.Count > 0
                      select new
                      {
                          title = ad.Ad.title,
                          id = ad.Ad.Id,
                          //other attributes
                      });
            return Ok(ret);
        }

要解决此异常问题，我在Application_Start Global.asax.cs中向protected void Application_Start() { AreaRegistration.RegisterAllAreas(); GlobalConfiguration.Configure(WebApiConfig.Register); FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters); RouteConfig.RegisterRoutes(RouteTable.Routes); BundleConfig.RegisterBundles(BundleTable.Bundles); GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore; GlobalConfiguration.Configuration.Formatters.Remove(GlobalConfiguration.Configuration.Formatters.XmlFormatter); } 函数添加了两行：

Register

但它没有用。然后，我在WebApiConfig.cs中的var json = configuration.Formatters.JsonFormatter; json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects; configuration.Formatters.Remove(configuration.Formatters.XmlFormatter); 函数末尾添加了以下行：

self.loadad = function () {
                url_address = '/api/Electronic/GetMobileTrends';
                $.ajax({
                    url: url_address,
                    dataType: "json",
                    contentType: "application/json",
                    cache: false,
                    type: 'GET',
                    success: function (data) {
                        var mappedads = $.map(data, function (item) { return new ad(item); });
                        self.showAds(mappedads);

                    },
                    error: function () {
                        toastr.error("Unable to load data. Please try again", "Error");
                    }
                });
            }

它仍然无效。我不想创建模型，因为我正在使用淘汰赛。此外，如果我为每个webapi调用创建模型。将有30到40个模型（每次调用中检索的数据不同）。

  

有没有办法在不创建模型的情况下解决此异常？

更新 我的问题不重复。 我的ajax功能是：

   #include <stdio.h>
   #include <stdlib.h>
   #include<iostream>
    using namespace std;
    int len;
   void swap (int *x, int *y)
  {
     int temp;
     temp = *x;
     *x = *y;
     *y = temp;
  }
   void print(const int *v)
  {
     int i;
     int size = len;
     if (v != 0) {
     for ( i = 0; i < size; i++) {
     cout<< v[i] ;
}
cout<<'\n';
}
}
void heappermute(int v[], int n) {
int i;
if (n == 1) {
    print(v);
}
else {
    for (i = 0; i < n; i++) {
        heappermute(v, n-1);
        if (n % 2 == 1) {
            swap(&v[0], &v[n-1]);
    }
        else {
            swap(&v[i], &v[n-1]);
        }
   }
  }
 }

 int main()
 {
  int num[11];
  int  i;
  cout<<"How many numbers you want to enter: ";
  cin>>len;
  cout<<"\nEnter the numbers: ";
  for ( i = 0 ; i < len; i++)
   cin>>num[i];
  heappermute(num, len);
  return 0;
 }