我有一对一的关系到同一个类叫用户, 我在web apis get方法中返回一个用户实例
它工作正常,只要我没有任何
User
ID | Name
0 | A
1 | B
Friends Table ( This table is used to build the one to many relationship )
User_ID | Friend_ID
1 | 0
0 | 1
这是我的GetMethod
[HttpGet]
public Models.User Authenticate()
{
try
{
return db.Users.SingleOrDefault(x => x.ID == 0 ) ;
}
catch
{
return null;
}
}
如果我得到并返回一个用户实体,那么我会得到打击错误
任何人都可以帮我修复以下错误？
{“Message”:”An error has occurred.”,”ExceptionMessage”:”The ‘ObjectContent`1’ type failed to serialize the response body for content type ‘text/html; 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.Friend_E5C79F4736EB2750392FFC7061B18E9C12F15F9583409603C75C5D1B1F7358D4’. Path ‘Friends1[0].User.Friends’.”,”ExceptionType”:”Newtonsoft.Json.JsonSerializationException”,”StackTrace”:” at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CheckForCircularReference(JsonWriter writer,Object value,JsonProperty property,JsonContract contract,JsonContainerContract containerContract,JsonProperty containerProperty)rn at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer,IWrappedCollection values,JsonArrayContract contract,JsonProperty member,JsonContainerContract collectionContract,JsonProperty containerProperty)rn at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer,JsonContract valueContract,JsonProperty containerProperty)rn at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer,JsonObjectContract contract,JsonProperty containerProperty)rn at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter,Object value)rn at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter,Object value)rn at Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter,Object value)rn at System.Net.Http.Formatting.JsonMediaTypeFormatter.<>c__DisplayClassd.b__c()rn at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action,CancellationToken token)”}}
解决方法
尝试更改webApi格式化程序.在WebApiConfig.cs中添加这些行：
var json = config.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
config.Formatters.Remove(config.Formatters.XmlFormatter);
并添加以下行：
json.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
（编辑：李大同）
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