Question

I’m creating 2 wcf services – ADService & DBService. I’m using DTO’s called EmployeeDTO and CustomerDTO to exchange data between endpoints.
I can’t add any of the services as Service References to other project in my solution and when I run the WCF host and try to access ADService.svc or DBService.svc I get the following:

    Type 'DTOs.CustomerDTO' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute.  If the type is a collection, consider marking it with the CollectionDataContractAttribute.

and

    Type 'DTOs.EmployeeDTO' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute.  If the type is a collection, consider marking it with the CollectionDataContractAttribute.

my files look as following:

class CustomerDTO

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

    namespace DTOs
    {
        public class CustomerDTO
        {
            public int customerID;
            public string name;
            public string surname;
            public string street;
            public string post_code;
            public string city;
            public string country;
            public string personal_code;
            public string phone_number;
            public string group_type;
            public string employee;

            public CustomerDTO(int _customerID, string _name, string _surname, string _street, string _post_code, string _city, string _country, string _personal_code, string _phone_number, string _group_type, string _employee)
            {
                this.customerID = _customerID;
                this.name = _name;
                this.surname = _surname;
                this.street = _street;
                this.post_code = _post_code;
                this.city = _city;
                this.country = _country;
                this.personal_code = _personal_code;
                this.phone_number = _phone_number;
                this.group_type = _group_type;
                this.employee = _employee;
            }
        }
    }

class EmployeeDTO:

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

    namespace DTOs
    {
        public class EmployeeDTO
        {
            public string givenName;
            public string sn;
            public string telephoneNumber;
            public string sAMAccountName;
            public string title;
            public string Department;
            public string distinguishedName;
            public string OU;
            public bool enable;

            public EmployeeDTO(string _givenName, string _sn, string _telephoneNumber, string _sAMAccountName, string _title, string _Department, string _distinguishedName, string _OU, bool _enable)
            {
                this.Department = _Department;
                this.distinguishedName = _distinguishedName;
                this.givenName = _givenName;
                this.sAMAccountName = _sAMAccountName;
                this.sn = _sn;
                this.telephoneNumber = _telephoneNumber;
                this.title = _title;
                this.OU = _OU;
                this.enable = _enable;
            }
        }
    }

Web.config

<?xml version="1.0"?>
<configuration>
  <connectionStrings>
    <add name="ki_dbEntities" connectionString="metadata=res://*/Model1.csdl|res://*/Model1.ssdl|res://*/Model1.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=WIN-D3T41W1E5EB\SQLEXPRESS;Initial Catalog=ki_db;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient"/>
  </connectionStrings>
  <appSettings>
    <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" />
  </appSettings>
  <system.web>
    <compilation debug="true" targetFramework="4.5" />
    <httpRuntime targetFramework="4.5"/>
  </system.web>
  <system.serviceModel>
    <services>
      <service name="WcfHost.ADService">
        <endpoint address="" binding="basicHttpBinding" contract="WcfHost.IADService">
          <identity>
            <dns value="localhost" />
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8733/WcfServiceLibrary/ADService/" />
          </baseAddresses>
        </host>
      </service>
      <service name="WcfHost.DBService">
        <endpoint address="" binding="basicHttpBinding" contract="WcfHost.IDBService">
          <identity>
            <dns value="localhost" />
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8733/WcfServiceLibrary/DBService/" />
          </baseAddresses>
        </host>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, set the values below to false before deployment -->
          <serviceMetadata httpGetEnabled="true" httpsGetEnabled="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="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <protocolMapping>
      <add binding="basicHttpsBinding" scheme="https" />
    </protocolMapping>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
    <!--
        To browse web app root directory during debugging, set the value below to true.
        Set to false before deployment to avoid disclosing web app folder information.
      -->
    <directoryBrowse enabled="true"/>
  </system.webServer>

</configuration>

IADService.cs

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Runtime.Serialization;
    using System.ServiceModel;
    using System.Text;
    using System.Threading.Tasks;
    using DTOs;
    using System.Security.Principal;

    namespace WcfHost
    {
        // NOTE: You can use the "Rename" command on the "Refactor" menu to change the interface name "IADService" in both code and config file together.
        [ServiceContract]
        public interface IADService
        {
            [OperationContract]
            bool setConnection();
            .
            .
            .
            [OperationContract]
            Task changeAccountStatus(EmployeeDTO _employee);

        }
    }

IDBService.cs is defined analogically.

I can’t seem to find the cause of this error especially that a friend of mine has a similar implementation and it works while mine does not.
Any help would be deeply appreciated.

Answer 1

To serialize a class over the wire you need to mark it (as it says) with the DataContract and DataMember attribute. I believe you also need to convert those fields to properties. So you need:

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

namespace DTOs
{
    [DataContract]
    public class CustomerDTO
    {
        [DataMember]
        public int customerID { get; set; }

        [DataMember]
        public string name { get; set; }

        [DataMember]
        public string surname { get; set; }

        [DataMember]
        public string street { get; set; }

        [DataMember]
        public string post_code { get; set; }

        [DataMember]
        public string city { get; set; }

        [DataMember]
        public string country { get; set; }

        [DataMember]
        public string personal_code { get; set; }

        [DataMember]
        public string phone_number { get; set; }

        [DataMember]
        public string group_type { get; set; }

        [DataMember]
        public string employee { get; set; }

        public CustomerDTO(int _customerID, string _name, string _surname, string _street, string _post_code, string _city, string _country, string _personal_code, string _phone_number, string _group_type, string _employee)
        {
            this.customerID = _customerID;
            this.name = _name;
            this.surname = _surname;
            this.street = _street;
            this.post_code = _post_code;
            this.city = _city;
            this.country = _country;
            this.personal_code = _personal_code;
            this.phone_number = _phone_number;
            this.group_type = _group_type;
            this.employee = _employee;
        }
    }
}

Because your operation contract uses the EmployeeDTO type as an input parameter, that means the client needs to be able to create that type and send it over the wire to the server. So it must be attributed with [DataContract].