c# - 使用自定义 Json 序列化器创建集合

Question

此代码是 ASP.Net Web API Controller 的一部分，我有一个特殊要求，需要在将最终 Json 发送到 UI 之前修改其中的某些值

我当前的代码如下:

// Web API controller

public partial class ViewRController
        {
       [HttpGet]
            public DataMapList FetchEmployeeDataList()
            {
                DataMapList returnDataMapList = new DataMapList();

                return (returnDataMapList);
            }
        }

// Type definition and details

    [JsonObject]
        [JsonConverter(typeof(DataMapListSerializer))]
        public class DataMapList
        {
            public List<Dictionary<object, object>> employeeSalaryMappingList = null;

            public DataMapList()
            {
                employeeSalaryMappingList = new List<Dictionary<object, object>>();
                employeeSalaryMappingList.Add(new Dictionary<object, object>());

                employeeSalaryMappingList[0].Add(1, 10000);
                employeeSalaryMappingList[0].Add(2, 13000);
                employeeSalaryMappingList[0].Add(3, 15000);

                employeeSalaryMappingList.Add(new Dictionary<object, object>());

                employeeSalaryMappingList[1].Add(4, 9000);
                employeeSalaryMappingList[1].Add(5, 12000);
                employeeSalaryMappingList[1].Add(6, 11000);
            }
        }

// Custom Json serializer

public class DataMapListSerializer : JsonConverter
    {
        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            var employeeSalaryDataMapList = value as DataMapList;
            var employeeSalaryMappingList = employeeSalaryDataMapList.employeeSalaryMappingList;


            writer.WriteStartObject();
            foreach (var employeeSalaryMappingDictionary in employeeSalaryMappingList)
            {
                writer.WritePropertyName("ED");
                writer.WriteStartObject();

                foreach (var keyValuePair in employeeSalaryMappingDictionary)
                {
                    writer.WritePropertyName("ID-" + keyValuePair.Key);
                    serializer.Serialize(writer, keyValuePair.Value);
                }

                writer.WriteEndObject();
            }

            writer.WriteEndObject();
        }       

        public override bool CanConvert(Type objectType)
        {
            return typeof(DataMapList).IsAssignableFrom(objectType);
        }
    }

我面临的问题如下是我的结果:

{ 
   "ED": { "ID-1": 10000, "ID-2": 13000, "ID-3": 15000 }, 
  "ED": { "ID-4": 9000, "ID-5": 12000, "ID-6": 11000 } 
}

但是我期望以下结果，因为我正在序列化集合(.Net 列表类型，.Net 集合)

[ 
   "ED": { "ID-1": 10000, "ID-2": 13000, "ID-3": 15000 }, 
  "ED": { "ID-4": 9000, "ID-5": 12000, "ID-6": 11000 } 
]

事实上，当我尝试在 Json Lint 中验证时，当前结果，它显示有效的 Json 但终止了其中的一部分，因此它显示以下内容为有效的 Json，但这只是一个转移

{
    "ED": {
        "ID-4": 9000,
        "ID-5": 12000,
        "ID-6": 11000
    }
}

我尝试替换 writer.WriteStartObject();和writer.WriteEndObject();通过 writer.WriteStartArray();和writer.WriteEndArray(); ，在遍历类型中的 List 的第一个 foreach 循环之前，但这会导致异常，所以没有帮助

"exceptionMessage": "Token StartArray in state ObjectStart would result in an invalid JSON object. Path '

任何解决问题的建议，如果您需要任何说明，请告诉我

Answer 1

在 JSON ，名称-值对必须位于对象 {} 内；它们不能直接位于数组 [] 内。因此，您尝试创建的 JSON 无效，这就是您收到异常的原因:

[ 
   "ED": { "ID-1": 10000, "ID-2": 13000, "ID-3": 15000 }, 
   "ED": { "ID-4": 9000, "ID-5": 12000, "ID-6": 11000 } 
]

为了使其成为有效的集合，每个 ED 名称-值对必须包装在如下对象中:

[ 
   { 
      "ED": { "ID-1": 10000, "ID-2": 13000, "ID-3": 15000 } 
   }, 
   { 
      "ED": { "ID-4": 9000, "ID-5": 12000, "ID-6": 11000 } 
   }
]

一旦您看到这一点，解决方案就变得清晰了:在您的 DataMapListSerializer 中，您需要使用 writer.WriteStartArray() 和 writer.WriteEndArray() code> 在循环之外，并且您需要在循环内添加 writer.WriteStartObject() 和 writer.WriteEndObject() 。

    writer.WriteStartArray();

    foreach (var employeeSalaryMappingDictionary in employeeSalaryMappingList)
    {
        writer.WriteStartObject();

            writer.WritePropertyName("ED");
            writer.WriteStartObject();

            foreach (var keyValuePair in employeeSalaryMappingDictionary)
            {
                writer.WritePropertyName("ID-" + keyValuePair.Key);
                serializer.Serialize(writer, keyValuePair.Value);
            }

            writer.WriteEndObject();

        writer.WriteEndObject();
    }

    writer.WriteEndArray();

fiddle :https://dotnetfiddle.net/OT4HKM