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Why the web service can not directly return a JSON string?

  1. #1
    May 03, 2012, 11:26 AM

    Why the web service can not directly return a JSON string?

    my code:
        <ext:ComboBox ID="OrderNo" 
                runat="server" 
                DisplayField="sOrder_No" 
                ValueField="sOrder_No"
                TypeAhead="false"
                LoadingText="Searching..." 
                Width="150" ListWidth="400"
                PageSize="10"
                HideTrigger="true"
                ItemSelector="tr.list-item"   
                MinChars="2"  FieldLabel="采购单号">
                <Store>
                    <ext:Store ID="Store1" runat="server" AutoLoad="false">
                        <Proxy>
                              <ext:HttpProxy Json="true"  Method="POST" Url="../../Common/Query.asmx/PagingQuery" />
                        </Proxy>
                        <BaseParams>
                            <ext:Parameter Name="querytype" Value="OrderNo" Mode="Value" />
                        </BaseParams>
                        <Reader>
                            <ext:JsonReader Root="d.Data" TotalProperty="d.TotalRecords">
                                <Fields>
                                    <ext:RecordField Name="sOrder_No" />
                                    <ext:RecordField Name="nBuy_Date"  />
                                    <ext:RecordField Name="sFac_Id" />
                                    <ext:RecordField Name="sFac_Name" />
                                </Fields>
                            </ext:JsonReader>
                        </Reader>
                    </ext:Store>
                </Store>
                <Template ID="Template1" runat="server">
                   <Html>
					   <tpl for=".">
						<tpl if="[xindex] == 1">
							<table class="cbStates-list">
								<tr>
									<th>采购单号</th>
									<th>采购日期</th>
                                    <th>厂商编码</th>
                                    <th>厂商名称</th>
								</tr>
						</tpl>
						<tr class="list-item">
							<td style="padding:3px 3px;">{sOrder_No}</td>
							<td>{nBuy_Date}</td>
                            <td>{sFac_Id}</td>
                            <td>{sFac_Name}</td>
						</tr>
						<tpl if="[xcount-xindex]==0">
							</table>
						</tpl>
					</tpl>
				   </Html>
                </Template>
                </ext:ComboBox>
    WebService:
    using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using DBUtility;
using System.Data;
using Newtonsoft.Json.Converters;
using Newtonsoft.Json;
using Ext.Net;

namespace Web
{
   
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    [System.Web.Script.Services.ScriptService]
    public class Query : System.Web.Services.WebService
    {

              
        [WebMethod]
        public string PagingQuery(int start, int limit, string query, string querytype)
        {
           
            int count=0;
            DataTable dt = GetOrderList(query, start, limit, out count);

            string result = JsonConvert.SerializeObject(dt, new DataTableConverter());

            return string.Format("{{Data:{0},TotalRecords:{1}}}", result, count);
          
        }


        private DataTable GetOrderList(string query, int start, int limit, out int count)
        {

            DataTable dt = new DataTable();
            dt.Columns.Add(new DataColumn("sOrder_No", typeof(string)));
            dt.Columns.Add(new DataColumn("nBuy_Date", typeof(string)));
            dt.Columns.Add(new DataColumn("sFac_Id", typeof(string)));
            dt.Columns.Add(new DataColumn("sFac_Name", typeof(string)));

            dt.Rows.Add("9TC09000133", "20090505", "1F019", "Dong Guan");
            dt.Rows.Add("9TC09000134", "20090504", "1F018", "Tong Tuan");

            count = 100;

            return dt;
        }

       
    }
}
    error meeage:
    Click image for larger version.  Name: 捕获.JPG  Views: 202  Size: 31.3 KB  ID: 4191

    json string format seems to have been damaged.
    {"d":"{Data:[{\"sOrder_No\":\"9TC09000133\",\"nBuy_Date\":\"20090505\",\"sFac_Id\":\"1F019\",\"sFac_Name\":\"Dong Guan\"},{\"sOrder_No\":\"9TC09000134\",\"nBuy_Date\":\"20090504\",\"sFac_Id\":\"1F018\",\"sFac_Name\":\"Tong Tuan\"}],TotalRecords:100}"}
  2. #2
    May 04, 2012, 9:51 AM
    Take a look at this article
    http://encosia.com/asp-net-web-servi...serialization/

    I have found the webservices is very difficult to use when calling the code from a different domain, you can use a httphandler instead
    Also please note that WCF services will handle both cross domain and json out of the box

    hth /Peter
  3. #3
    May 05, 2012, 1:21 AM
    Quote Originally Posted by plykkegaard View Post
    Take a look at this article
    http://encosia.com/asp-net-web-servi...serialization/

    I have found the webservices is very difficult to use when calling the code from a different domain, you can use a httphandler instead
    Also please note that WCF services will handle both cross domain and json out of the box

    hth /Peter
    Thanks for Peter.
    I have to switch httphandler to solve this problem.
    Perhaps maybe use a custom of the webservice, but I have not tested.
    Refer to the article:http://www.cnblogs.com/xiaoyin_net/a...8/1406071.html
    public class EnhancedWebService : System.Web.Services.WebService
    {
        public EnhancedWebService()
            : base()
        {
            string ServiceMethodName = GetMethodName();
            bool IsJSON = Context.Request.QueryString["form"] == "json";
            if (IsJSON) InterceptJSONMethodRequest(ServiceMethodName);
        }
        private string GetMethodName()
        {
            return Context.Request.Url.Segments[Context.Request.Url.Segments.Length - 1];
        } 
        private void InterceptJSONMethodRequest(string ServiceMethodName)
        { 
            JSONMethodAttribute JMA = GetMethodJSONMethodAttribute(ServiceMethodName);
            if (JMA == null)
            {
                Context.Response.Write("throw new Exception('The Web Service method " + 
                                       ServiceMethodName + " is not available " + 
                                       "as a JSON function. For more " + 
                                       "information contact " + 
                                       "the Web Service Administrators.');");
            }
            else
            { 
                //ToDo: deserialize parameters, call target method, 
                //      deserialize and write return value
            }
            Context.Response.Flush();
            Context.Response.End();
        } 
        private JSONMethodAttribute GetMethodJSONMethodAttribute(string WebServiceMethodName)
        {
            MethodInfo ActiveMethod = this.GetType().GetMethod(WebServiceMethodName);
            JSONMethodAttribute JMA = null;
            if (ActiveMethod != null)
            {
                object[] Attributes = ActiveMethod.GetCustomAttributes(true);
                foreach (object Attribute in Attributes)
                {
                    if (Attribute.GetType() == typeof(JSONMethodAttribute))
                    {
                        JMA = (JSONMethodAttribute)Attribute;
                    }
                }
            }
            return JMA;
        }
    }
}

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