使用JsonWriter的C＃/ Datable错误：无效的JSON原语：draw

Question

我的数据表有问题。我收到错误：＆＃34;无效的JSON原语：draw。＆＃34;当我尝试从我的Web服务返回JSON时。很确定返回的JSON格式不正确，但我不确定如何纠正它。

使用Javascript：

 $(document).ready(function () {
        var dt = $('#example').DataTable({
            processing: true,
            serverSide: true,
            pagingType: 'full_numbers',
            ajax: {
                url: 'http://localhost:49317/WebService2.asmx/GetTableData',
                type: 'POST',
                dataType: 'json',
                contentType: 'application/json; charset=utf-8',
                dataSrc:  'data'
            },
            columns: [                    
                { data: 0 },
                { data: 1 },
                { data: 2 },
                { data: 3 },
                { data: 4 }
            ],
            order: [[1, 'asc']]
        });

HTML：

 <div>
    <table id="example" class="table table-striped table-bordered" cellspacing="0" cellpadding="2" width="100%">  
       <thead>
          <tr>

             <th>Job</th>
             <th>Customer</th>
             <th>Planner</th>
             <th>Description</th>  
              <th>SO</th>                 
          </tr>
       </thead>
       <tbody>

       </tbody>
    </table>  
</div>

代码隐藏：

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.Script.Services;
using System.Web.Services;
using System.Data;
using System.Data.OleDb;
using Newtonsoft.Json;
using System.IO;


[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService]
public class WebService2 : System.Web.Services.WebService
{
    public class JQDTParams
    {
        public string draw { get; set; }
    }

    [WebMethod(EnableSession = true)]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet =false)]
    public string GetTableData(JQDTParams param)
    {

        var sortOrder = "asc";

        string connString = "Provider=Microsoft.ACE.OLEDB.12.0;data source=|DataDirectory|ProductionDataCopy.mdb";

        DataTable results = new DataTable();
        using (OleDbConnection conn = new OleDbConnection(connString))
        {
            OleDbCommand cmd = new OleDbCommand("SELECT * FROM ProductionData", conn);
            conn.Open();
            OleDbDataAdapter adapter = new OleDbDataAdapter(cmd);
            adapter.Fill(results);
        }

        IEnumerable<DataRow> sequence = results.AsEnumerable();
        var records = sequence.ToList();

        var orderedResults = sortOrder == "asc"
                             ? records.OrderBy(o => o["Job"])
                             : records.OrderBy(o => o["Job"]);


        StringBuilder sb1 = new StringBuilder();
        StringWriter sw = new StringWriter(sb1);

        using (JsonWriter writer = new JsonTextWriter(sw))
        {
           writer.WriteStartObject();
            writer.WritePropertyName("draw");
            writer.WriteValue(param.draw.ToString());
            writer.WritePropertyName("recordsTotal");
            writer.WriteValue(records.Count);
            writer.WritePropertyName("recordsFiltered");
            writer.WriteValue(records.Count);
            writer.WritePropertyName("data");
            writer.WriteStartArray();

            foreach (var result in orderedResults)
            {
                writer.WriteStartArray();
                //writer.WriteValue("< img class='image-details' src='content/DataTables-1.10.4/images/details_open.png' runat='server' height='16' width='16' alt='View Details'/>");
                writer.WriteValue(result["Job"]);
                writer.WriteValue(result["Customer"]);
                writer.WriteValue(result["Planner"]);
                writer.WriteValue(result["Description"]);
               //writer.WriteValue(result["so"]);
                writer.WriteValue("so");
                writer.WriteEndArray();
            }

            writer.WriteEndArray();
            writer.WriteEndObject();
            writer.Flush();
            writer.Close();
        }

        sw.Close();
        string Json = sb1.ToString();
        //JavaScriptSerializer serializer = new JavaScriptSerializer();
        //var Json = serializer.Serialize(sb1);
        return Json;
    }

}