WCF WebService Not Returning DataTable

Question

I am beginning to use WCF to write a web service instead of the old asp.net asmx way. I want to be able to return JSON so I can't do it the old way. If I am returning a string or int the Web Service works fine but if I try to return a DataTable it becomes unresponsive and I get nothing. I have tried debugging to see where it blows up and it won't even stop on a breakpoint.

My Class file looks like this:

 public string XMLData(string id)
    {
        return "You requested " + id;
    }


    public string JSONData(string id)
    {
        return "You requested " + id;
    }

    public DataTable TestDT()
    {
        DataTable Testing = new DataTable("TestDT");

        return Testing;
    }

My interface file looks like this:

    [OperationContract]
    [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Xml, BodyStyle = WebMessageBodyStyle.Wrapped,
        UriTemplate = "xml/{id}")]
    string XMLData(string id);

    [OperationContract]
    [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped,
        UriTemplate = "json/{id}")]
    string JSONData(string id);

    [OperationContract]
    [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped,
        UriTemplate = "testdt/")]
    DataTable TestDT();

The json method as well as the xml method works perfectly fine. When I call TestDT I get a standard IE Page showing no connectivity. I have tried it with data or no data in the datable with the same results.

One other note here: when I run the WCF service locally (Hitting PLAY) my test application shows now services I see this:

How can I get this to work with a datable?

Edit#1: I actually resolved the issue with the data not returning. I finally gave up on trying to return a dataset and instead I created a jagged array and ended up return it as JSON. I'll post it later as an answer so people know how I did it. What I am more interested in knowing now is part 2. Why is my WCF Test Client not showing any methods (see image attached) My hunch is its related to the web.config so I am posting that below:

<?xml version="1.0"?>
<configuration>
  <connectionStrings>
    <add name="DBDjuggleWS" connectionString="Data Source=localhost;Initial Catalog=PrayUpDev;Persist Security Info=True;User=DjuggleMaster;Password=DJPassword!" providerName="System.Data.SqlClient"/>
  </connectionStrings>
  <system.web>
    <compilation debug="true" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <services>
      <service name ="PrayUpService.PrayUp" behaviorConfiguration="ServiceBehaviour">
        <endpoint address="" binding="webHttpBinding" contract="PrayUpService.IPrayUp" behaviorConfiguration ="web"></endpoint>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="ServiceBehaviour">
          <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
          <serviceMetadata httpGetEnabled="true"/>
          <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="true"/>
        </behavior>
      </serviceBehaviors>
      <endpointBehaviors>
        <behavior name="web">
          <webHttp/>
        </behavior>
      </endpointBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
 <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>

</configuration>

Consider to return using Data Contract. If there is only one column with multiple rows you can consider to return as List(string). — Baskar Rao, Apr 07 '17 at 05:48
Possible duplicate of [Returning DataTables in WCF/.NET](http://stackoverflow.com/questions/12702/returning-datatables-in-wcf-net) — hvojdani, Apr 08 '17 at 05:43

score 0 · Answer 1 · edited May 23 '17 at 11:46

you shoud return DataSet instead of DataTable but Returning data sets from web services is not typically considered a “good practice”. here you can read about it: Why returning dataset or data table from WCF service is not a good practice? What are the Alternatives?

i highly recommend use the DataSet’s methods to get the data in XML format and pass the XML string instead of the DataSet itself to the service.

PassDataSet(dsDataSet.GetXmlSchema(), dsDataSet.GetXml())

WCF WebService Not Returning DataTable

1 Answers1