错误：无法在 LINQ to Entities 查询中构造实体或复杂类型

Question

我收到此错误“System.NotSupportedException：无法在 LINQ to Entities 查询中构造实体或复杂类型“MyModel.Team”。”当我导航到 Team/Index/{id} 页面时。有人可以指出我犯的错误吗？

控制器：

public ActionResult Index(int id)
    {
        IQueryable<Team> teams = teamRepository.GetTeamByPersonID(id);   
        return View("Index", teams);
    }

存储库：

public IQueryable<Team> GetTeamByPersonID(int id)
    {
        return from t in entities.Teams
               join d in entities.Departments
                on t.TeamID equals d.TeamID
               where (from p in entities.Person_Departments
                      join dep in entities.Departments
                      on p.DepartmentID equals dep.DepartmentID
                      where p.PersonID == id
                      select dep.TeamID).Contains(d.TeamID)
               select new Team
               {
                   TeamID = t.TeamID,
                   FullName = t.FullName,
                   ShortName = t.ShortName,
                   Iso5 = t.Iso5,
                   DateEstablished = t.DateEstablished,
                   City = t.City,
                   CountryID = t.CountryID
               };
    }

视图模型：

public IQueryable<Team> teamList { get; set; }
public TeamViewModel(IQueryable<Team> teams)
    {
         teamList = teams;
    }

视图：

<% foreach (var team in Model){ %>
    <tr>
        <td><%: Html.ActionLink(team.ShortName, "Details", new { id=team.TeamID}) %></td>
        <td><%: team.City %></td>
        <td><%: team.Country %></td>
    </tr>
<% } %>

Answer 1

问题在于您正在 select 语句中创建一个 Team 类，而 LINQ to SQL 不支持该类。将您的 select 更改为：

select t

或使用匿名类型：

select new
{
    TeamID = t.TeamID,
    FullName = t.FullName,
    ShortName = t.ShortName,
    Iso5 = t.Iso5,
    DateEstablished = t.DateEstablished,
    City = t.City,
    CountryID = t.CountryID
};

或使用 DTO（任何非实体）：

select new TeamDTO
{
    TeamID = t.TeamID,
    FullName = t.FullName,
    ShortName = t.ShortName,
    Iso5 = t.Iso5,
    DateEstablished = t.DateEstablished,
    City = t.City,
    CountryID = t.CountryID
};

Answer 2

如果类 Team 是一个实体，则无法在 linq 语句内创建它。您应该考虑创建自己的类并返回它。或者也许只是选择t。