WCF 方法不从 EF 返回结果

Question

我的解决方案中有一个 WCF 项目和一个 EF 项目，我正在调用我的 EF 以获取一个对象，但我得到了 null 返回。我不知道为什么，因为我的 SQL Server 数据库中确实有数据，如果这对线索有任何影响，我将使用数据库优先建模。

我在 SQL Server 管理工具中的每个表都有数据，但是当我向 GetUser 方法添加断点并单步执行时，每个表对象的计数为 0，最后我返回一个User 对象，它是null

WCF 方法

    public User GetUser(string username, string password)
    {
        User user = new User();
        try
        {
            if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
            {
                throw new Exception("Invalid username and password");
            }
            var context = new InventoryManagerEntities();
            var userContext =
                (from usr in context.Users
                    where usr.usr_Username == username && user.usr_Password == password
                    select usr).FirstOrDefault();

        }
        catch (Exception)
        {
            throw;
        }
        return user;
    } 

WCF 应用程序配置

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <connectionStrings><add name="InventoryManagerEntities" connectionString="metadata=res://*/InventoryManagerDBModels.csdl|res://*/InventoryManagerDBModels.ssdl|res://*/InventoryManagerDBModels.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=JUNIORLABOLD4A3\SQLEXPRESS;initial catalog=InventoryManager;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" /><add name="InventoryManagerEntities1" connectionString="metadata=res://*/Model.csdl|res://*/Model.ssdl|res://*/Model.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=JUNIORLABOLD4A3\SQLEXPRESS;initial catalog=InventoryManager;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" /></connectionStrings>
  <system.web>
    <compilation debug="true" />
  </system.web>
  <!-- When deploying the service library project, the content of the config file must be added to the host's 
  app.config file. System.Configuration does not support config files for libraries. -->
  <system.serviceModel>
    <services>
      <service name="InventoryManager.Services.UserService">
        <endpoint address="" binding="basicHttpBinding" contract="InventoryManager.Services.IUserServices">
          <identity>
            <dns value="localhost" />
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8733/Design_Time_Addresses/InventoryManager.Services/UserService/" />
          </baseAddresses>
        </host>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, 
          set the value below to false 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="False" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
</configuration>

EF 类库 App.Config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
  <connectionStrings>
    <add name="InventoryManagerEntities" 
         connectionString="metadata=res://*/InventoryManagerDBModels.csdl|res://*/InventoryManagerDBModels.ssdl|res://*/InventoryManagerDBModels.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=JUNIORLABOLD4A3\SQLEXPRESS;initial catalog=InventoryManager;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework&quot;" 
         providerName="System.Data.EntityClient" />
  </connectionStrings>
</configuration>

Answer 1

您的代码中有两个错误。变量user 从未赋值，谓词user.usr_Password == password 错误。

public User GetUser(string username, string password)
{
    User user = new User(); // <= user is only initialized
    try
    {
        if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
        {
            throw new Exception("Invalid username and password");
        }
        var context = new InventoryManagerEntities();
        var userContext = // <= should be "user", not "var userContext"
            (from usr in context.Users
                where usr.usr_Username == username 
                   && user.usr_Password == password // <= should be usr.usr_Password
                select usr).FirstOrDefault();

    }
    catch (Exception)
    {
        throw;
    }
    return user;
} 

所以，在消除所有噪音之后：

if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
{
    throw new Exception("Invalid username and password");
}
var context = new InventoryManagerEntities();
return (from usr in context.Users
        where usr.usr_Username == username 
           && usr.usr_Password == password
        select usr).FirstOrDefault();