wcf发送json并接收不同对象的json响应

Question

我想创建一个服务，它接收一种类型的json对象并发送回不同的对象。当我使用相同的对象类型进行请求和响应时，一切正常。但是，当我更改我发回的对象时，我得到错误请求400 可以帮助一些吗？

 public interface IOrderService
    {    
        [OperationContract]
        [WebInvoke(UriTemplate = "/GetTablesDataResponse",
            RequestFormat = WebMessageFormat.Json,
            ResponseFormat = WebMessageFormat.Json, Method = "POST")]
        MetaDataResponseContract GetTablesDataResponse(TablesMetaDataContract TablesRequest);
    }
}

TablesMetaDataContract

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.Text;

namespace GetMetaDataWcfSvc
{
    [DataContract]
    public class TablesMetaDataContract
    {
        [DataMember]
        public Header Header { get; set; }
        [DataMember]
        public Body Body { get; set; }
    }

    [DataContract]
    public class Header
    {}

    [DataContract]
    public class Body
    {
        [DataMember]
        public get_MetaData_request get_MetaData_request { get; set; }
    }


    [DataContract]
    public class get_MetaData_request
    {
        [DataMember]
        public service_control service_control { get; set; }

        [DataMember]
        public service_data service_data { get; set; }
    }

    [DataContract]
    public class service_control
    {
        [DataMember]
        public string application_src { get; set; }
        [DataMember]
        public string transaction_id { get; set; }
        [DataMember]
        public string process_name { get; set; }
        [DataMember]
        public string request_datetime { get; set; }
    }

    [DataContract]
    public class service_data
    {
        [DataMember]
        public tables_name tables_name { get; set; }
    }

    [DataContract]
    public class tables_name
    {
        [DataMember]
        public List<string> table_name { get; set; }
    }
}

MetaDataResponseContract

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Runtime.Serialization;
using System.Web;

namespace GetMetaDataWcfSvc
{
        [DataContract]
        public class MetaDataResponseContract
        {
            [DataMember]
            public service_status service_status { get; set;}
            [DataMember]
            public OutputParameters OutputParameters {get; set; }

        }
        [DataContract]
        public class service_status
        {
            [DataMember]
            public string return_code { get; set; }
            [DataMember]
            public string return_desc { get; set; }
        }
        [DataContract]
        public class Column
        {
            [DataMember]
            public string name { get; set; }
            [DataMember]
            public string sqltype { get; set; }
            [DataMember]
            public string text { get; set; }
        }
        [DataContract]
        public class Row
        {
            [DataMember]
            public List<Column> Column { get; set; }
        }
        [DataContract]
        public class Table
        {
            [DataMember]
            public string name { get; set; }


            [DataMember]
            public List<Row> Row { get; set; }
        }
        [DataContract]
        public class OutputParameters
        {
            [DataMember]
            public Table Table { get; set; }
        }
}

服务功能

 public MetaDataResponseContract GetTablesDataResponse(TablesMetaDataContract TablesRequest)
        {
            TablesRequest.Body.get_MetaData_request.service_control.process_name = "server";
            string ProcessName = TablesRequest.Body.get_MetaData_request.service_control.process_name;
            string RequestDateTime = TablesRequest.Body.get_MetaData_request.service_control.request_datetime;
            List<string> TablesList = new List<string> { };

            GetDataTable(ProcessName);

            MetaDataResponseContract TablesListResponse = new MetaDataResponseContract();

            TablesListResponse.service_status.return_desc = "susccess";

//if i return TablesRequest and change return type in function it is working

            return TablesListResponse;
        }

客户端

 DataContractJsonSerializer ser =
                    new DataContractJsonSerializer(typeof(TablesMetaDataContract));
            MemoryStream mem = new MemoryStream();
            ser.WriteObject(mem, TablesRequest);
            string data =
                Encoding.UTF8.GetString(mem.ToArray(), 0, (int)mem.Length);
            WebClient webClient = new WebClient();
            webClient.Headers["Content-type"] = "application/json";
            webClient.Encoding = Encoding.UTF8;
            try
            {

                string t = webClient.UploadString("http://localhost:63702/OrderService.svc/GetTablesDataResponse", "POST", data);
            }
            catch (Exception ex)
            {
                string x = ex.ToString();
            }