EF实体生成关系导致相互循环取数据出现异常"Self referencing loop detected for property "

异常信息：

Self referencing loop detected for property 'md_agent' with type 'System.Data.Entity.DynamicProxies.md_agent_5F7CB7C257B9164D0D18D2B3E8DA3838A3ED1C7F5D326A56B71D51234B89C401'. Path '[1].md_design[0]'.
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CheckForCircularReference(JsonWriter writer, Object value, JsonProperty property, JsonContract contract, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues(JsonWriter writer, Object value, JsonContainerContract contract, JsonProperty member, JsonProperty property, JsonContract& memberContract, Object& memberValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IEnumerable values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IEnumerable values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)
   at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)
   at Newtonsoft.Json.JsonSerializer.Serialize(TextWriter textWriter, Object value)
   at Ninesky.Core.Serialization.JsonNetResult.ExecuteResult(ControllerContext context)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass1e.<>c__DisplayClass28.<BeginInvokeAction>b__19()
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass1e.<BeginInvokeAction>b__1b(IAsyncResult asyncResult)

解决方法：直接從 Entity Framework 模型 (EDMX) 移除不必要的關聯屬性，以避免發生參考循環的狀況。