Question

我尝试使用以下控制器返回JSON对象：

    public async Task<IHttpActionResult> Get(string query)
    {
        var client = new HttpClient(new HttpClientHandler()
        {
            Credentials = new NetworkCredential("myuser", "NotSoSecret#1", "mydomain"),
        });
        var ipAddress = Dns.GetHostAddresses("myorgetc.com").ToList()[0];
        client.BaseAddress = new Uri(string.Format("http://{0}/myorg/api/data/v8.1/", ipAddress.ToString()));

        HttpResponseMessage response = await client.GetAsync(client.BaseAddress +"accounts"+ query);
        object result;

        if (response.IsSuccessStatusCode)
        {
            result = await response.Content.ReadAsAsync<object>();
            return Ok(result);
        }

        return NotFound();
    }

它返回了以下异常：

此XML文件似乎没有任何关联的样式信息用它。文档树如下所示。一个错误已经发生了。类型＆＃39; Newtonsoft.Json.Linq.JToken＆＃39;是一个递归收集数据合同这是不受支持的。考虑修改。的定义收集＆＃39; Newtonsoft.Json.Linq.JToken＆＃39;删除引用本身。 System.Runtime.Serialization.InvalidDataContractException 在 System.Runtime.Serialization.DataContract.ValidatePreviousCollectionTypes（类型 collectionType，Type itemType，Dictionary 2 previousCollectionTypes) at System.Runtime.Serialization.DataContract.GetNonDCTypeStableName(Type type, Dictionary 2 previousCollectionTypes）at System.Runtime.Serialization.DataContract.GetStableName（Type type，字典2 previousCollectionTypes, Boolean& hasDataContract) at System.Runtime.Serialization.DataContract.GetDefaultStableLocalName(Type type) at System.Runtime.Serialization.DataContract.GetDCTypeStableName(Type type, DataContractAttribute dataContractAttribute) at System.Runtime.Serialization.DataContract.GetStableName(Type type, Dictionary 2 previousCollectionTypes，Boolean＆amp; hasDataContract）at System.Runtime.Serialization.DataContract.GetCollectionStableName（类型 type，Type itemType，Dictionary`2 previousCollectionTypes， CollectionDataContractAttribute＆安培; collectionContractAttribute）at System.Runtime.Serialization.CollectionDataContract.CollectionDataContractCriticalHelper..ctor（类型 type，CollectionKind kind，Type itemType，MethodInfo getEnumeratorMethod，String serializationExceptionMessage，String deserializationExceptionMessage）at System.Runtime.Serialization.CollectionDataContract.CollectionDataContractCriticalHelper..ctor（类型 type，CollectionKind kind，Type itemType，MethodInfo getEnumeratorMethod，MethodInfo addMethod，ConstructorInfo 建设者） System.Runtime.Serialization.CollectionDataContract..ctor（类型类型， CollectionKind kind，Type itemType，MethodInfo getEnumeratorMethod， MethodInfo addMethod，ConstructorInfo构造函数，布尔值 isConstructorCheckRequired）at System.Runtime.Serialization.CollectionDataContract.IsCollectionOrTryCreate（类型 type，Boolean tryCreate，DataContract＆amp; dataContract，Type＆amp;物品种类， Boolean constructorRequired，Boolean skipIfReadOnlyContract）at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract（的Int32 id，RuntimeTypeHandle typeHandle，Type type）at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation（的Int32 id，RuntimeTypeHandle typeHandle，Type type）at System.Runtime.Serialization.DataContractSerializer.GetDataContract（DataContract declaredTypeContract，Type declaredType，Type objectType）at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent（XmlWriterDelegator writer，Object graph，DataContractResolver dataContractResolver）at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject（XmlWriterDelegator writer，Object graph，DataContractResolver dataContractResolver）at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions（XmlWriterDelegator writer，Object graph，DataContractResolver dataContractResolver）at System.Runtime.Serialization.DataContractSerializer.WriteObject（XmlWriter的作家，对象图） System.Net.Http.Formatting.XmlMediaTypeFormatter.WriteToStream（类型 type，Object value，Stream writeStream，HttpContent content）at System.Net.Http.Formatting.XmlMediaTypeFormatter.WriteToStreamAsync（类型 type，Object value，Stream writeStream，HttpContent内容， TransportContext transportContext，CancellationToken cancellationToken）---从前一个位置到底的堆栈跟踪结束抛出异常---在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务） System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务） System.Web.Http.Owin.HttpMessageHandlerAdapter.d__13.MoveNext（）

我做错了什么？如何在不知道开发时的确切结构的情况下返回JSON对象？

这是我的创业公司：

public static class Startup
    {
        // This code configures Web API. The Startup class is specified as a type
        // parameter in the WebApp.Start method.

        public static void ConfigureApp(IAppBuilder appBuilder)
        {
            // Configure Web API for self-host. 
            HttpConfiguration config = new HttpConfiguration();
            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

            var container = new UnityContainer();
            container.RegisterType<IAccountsRepository, AccountsRepository>(new HierarchicalLifetimeManager());
            container.RegisterType<IAccountService, AccountService>(new HierarchicalLifetimeManager());
            config.DependencyResolver = new UnityResolver(container);

            appBuilder.UseWebApi(config);
        }


    }

Answer 1

将此添加到您的WebApiConfig。

config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));

如果您仍然遇到相同的例外，请查看this answer并查看是否有帮助。

事实证明，错误是由于我有一个错误   从NuGet安装的Microsoft Web API包，其中包括   Json.NET。卸载后，它可以正常工作。

这可能是你的答案 - 如果没有，看看哪些其他包   你安装了（你不需要）并删除它们。

如何返回一个对象并将其格式化为json？

1 个答案: