类型'MyDTO'无法序列化 - Wcf服务

我正在创建2个wcf服务 - ADService和DBService . 我正在使用名为EmployeeDTO和CustomerDTO的DTO在 endpoints 之间交换数据 . 我无法将任何服务作为服务引用添加到我的解决方案中的其他项目，当我运行WCF主机并尝试访问ADService.svc或DBService.svc时，我得到以下内容：

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.

和

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.

我的文件如下：

类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文件

<?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是以类似方式定义的 .

我似乎无法找到这个错误的原因，特别是我的一个朋友有类似的实现，它的工作，而我的朋友没有 . 任何帮助将深表感谢 .