无法反序列化当前的JSON对象，为什么呢？ [英] Cannot deserialize the current JSON object, WHY?
问题描述
我试图使用的WebAPI从我的数据的基础上获得的员工列表，使用这种code：
这是我的客户MVC应用程序的code：
I'm trying to use a WebApi to get a list of Employees from my data base, using this code: This is the code of my client MVC Application:
string u = "http://localhost:1411/api/EmployeeAPI";
Uri uri = new Uri(u);
HttpClient httpClient = new HttpClient();
Task<HttpResponseMessage> response = httpClient.GetAsync(uri);
Task.WaitAll(response);
HttpResponseMessage resposta = response.Result;
var msg = resposta.Content.ReadAsStringAsync().Result;
Employee[] employees = JsonConvert.DeserializeObject<Employee[]>(msg);
return View(employees);
这是我的WebAPI的code：
And this is the code of my WebAPI:
public IEnumerable<Employee> GetEmployees()
{
return db.Employees.AsEnumerable();
}
但这种错误不断出现，我不明白为什么：
But this error keeps popping up and I can't understand why:
无法反序列化当前的JSON对象（例如{名：值}）
入式'DataAccess.Employee []'，因为类型需要一个JSON
阵列（例如[1,2,3]），以正确的反序列化。要解决这个错误
要么改变的JSON到一个JSON数组（例如[1,2,3]），或改变
反序列化类型，以便它是一个正常的.NET类型（例如不是
基本类型喜欢整数，而不是一个集合类型像数组或
列表），可以从JSON对象反序列化。
JsonObjectAttribute也可加入到用它强制类型
从JSON对象反序列化。路径消息，1号线，11位。
Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'DataAccess.Employee[]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly. To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object. Path 'Message', line 1, position 11.
我的Employee类：
My Employee Class:
namespace DataAccess
{
using System;
using System.Collections.Generic;
public partial class Employee
{
public Employee()
{
this.Products = new HashSet<Product>();
}
public int EmployeeId { get; set; }
public string Title { get; set; }
public string FirstName { get; set; }
public string MiddleName { get; set; }
public string LastName { get; set; }
public byte[] rowguid { get; set; }
public System.DateTimeOffset ModifiedDate { get; set; }
public virtual ICollection<Product> Products { get; set; }
}
}
JSON的输出我真的不知道如何得到它。
The Json output I'm not really sure how to get it
msg变量的内容：
我的味精变量返回
{\\消息\\：\\出现错误\\，\\ExceptionMessage \\：\\。在'ObjectContent`1类型没有序列化内容类型应用程序/ JSON响应主体; charset=utf-8'.\\\",\\\"ExceptionType\\\":\\\"System.InvalidOperationException\\\",\\\"StackTrace\\\":null,\\\"InnerException\\\":{\\\"Message\\\":\\\"An发生错误\\，\\ExceptionMessage \\：\\型检测自引用循环'System.Data.Entity.DynamicProxies.ProductSubCategory_9EC9A3706390DE6A3B51F713F0DDAC2162AFB5B3FAB8F8587C9A865333A7729A'.路径'[0].Products[0].ProductSubCategory.ProductCategory.ProductSubCategories'.\\\",\\\"ExceptionType\\\":\\\"Newtonsoft.Json.JsonSerializationException\\\",\\\"StackTrace\\\":\\\"在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CheckForCircularReference（JsonWriter作家，对象的值，JsonProperty财产，JsonContract合同，JsonContainerContract containerContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList（JsonWriter作家，IWrappedCollection值， JsonArrayContract合同，JsonProperty成员，JsonContainerContract collectionContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue（JsonWriter作家，对象的值，JsonContract valueContract，JsonProperty成员，JsonContainerContract containerContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject（JsonWriter作家，对象的值，JsonObjectContract合同，JsonProperty成员，JsonContainerContract collectionContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue（JsonWriter作家，对象的值，JsonContract valueContract，JsonProperty成员，JsonContainerContract containerContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject（JsonWriter作家，对象的值，JsonObjectContract合同，JsonProperty成员，JsonContainerContract collectionContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft .Json.Serialization.JsonSerializerInternalWriter.SerializeValue（JsonWriter作家，对象的值，JsonContract valueContract，JsonProperty成员，JsonContainerContract containerContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject（JsonWriter作家，对象的值，JsonObjectContract合同，JsonProperty成员，JsonContainerContract collectionContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue（JsonWriter作家，对象的值，JsonContract valueContract，JsonProperty成员，JsonContainerContract containerContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft。 Json.Serialization.JsonSerializerInternalWriter.SerializeList（JsonWriter作家，IWrappedCollection值，JsonArrayContract合同，JsonProperty成员，JsonContainerContract collectionContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue（JsonWriter作家，对象的值，JsonContract valueContract， JsonProperty成员，JsonContainerContract containerContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject（JsonWriter作家，对象的值，JsonObjectContract合同，JsonProperty成员，JsonContainerContract collectionContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json .Serialization.JsonSerializerInternalWriter.SerializeValue（JsonWriter作家，对象的值，JsonContract valueContract，JsonProperty成员，JsonContainerContract containerContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList（JsonWriter作家，IWrappedCollection值，JsonArrayContract合同，JsonProperty成员，JsonContainerContract collectionContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue（JsonWriter作家，对象的值，JsonContract valueContract，JsonProperty成员，JsonContainerContract containerContract，JsonProperty containerProperty）\\ r \\ n在Newtonsoft.Json。 Serialization.JsonSerializerInternalWriter.Serialize（JsonWriter jsonWriter，对象的值）\\ r \\ n在Newtonsoft.Json.JsonSerializer.SerializeInternal（JsonWriter jsonWriter，对象的值）\\ r \\ n在System.Net.Http.Formatting.JsonMediaTypeFormatter＆LT;> c__DisplayClassd .b__c（个）\\ r \\ n在System.Threading.Tasks.TaskHelpers.RunSynchronously（动作的动作，令牌的CancellationToken）\\}}
"{\"Message\":\"An error has occurred.\",\"ExceptionMessage\":\"The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.\",\"ExceptionType\":\"System.InvalidOperationException\",\"StackTrace\":null,\"InnerException\":{\"Message\":\"An error has occurred.\",\"ExceptionMessage\":\"Self referencing loop detected with type 'System.Data.Entity.DynamicProxies.ProductSubCategory_9EC9A3706390DE6A3B51F713F0DDAC2162AFB5B3FAB8F8587C9A865333A7729A'. Path '[0].Products[0].ProductSubCategory.ProductCategory.ProductSubCategories'.\",\"ExceptionType\":\"Newtonsoft.Json.JsonSerializationException\",\"StackTrace\":\" at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CheckForCircularReference(JsonWriter writer, Object value, JsonProperty property, JsonContract contract, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value)\r\n at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value)\r\n at System.Net.Http.Formatting.JsonMediaTypeFormatter.<>c__DisplayClassd.b__c()\r\n at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token)\"}}"
推荐答案
要阻止发生的历史的错误的最好方法是：
The best way to stop that error from occuring is:
在您的WebAPI项目进入App_Start文件夹，并添加到WebApiConfig code这四行：
In your WebApi project go to the App_Start folder and add to the WebApiConfig this four lines of code:
config.EnableSystemDiagnosticsTracing();
config.Formatters.JsonFormatter.SerializerSettings.PreserveReferencesHandling = PreserveReferencesHandling.None;
config.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
config.Formatters.JsonFormatter.SerializerSettings.Formatting = Formatting.Indented;
config.Formatters.Remove(config.Formatters.XmlFormatter);
和确保你已经instaled JSON的包的NuGet
and make sure you have instaled the Json nuget package
这篇关于无法反序列化当前的JSON对象，为什么呢？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
