Question

我在尝试获取要显示的列表的值时收到异常错误。我试图为每个用户获取数据库中的所有项目数据。我认为我的LINQ表达式是错误的，但我不确定。

型号：

        public class ListModel
    {
        public List<StaffModel> StaffModelList { get; set; } 
    }
        public class StaffModel
    {
        public FlexModel Flex { get; set; }
        public List<Project> Projects { get; set; }
    }

        public partial class Project
    {
        public Project()
        {
            TimesheetEntries = new HashSet<TimesheetEntry>();
            UserProjects = new HashSet<UserProject>();
        }

        [StringLength(50)]
        public string ProjectId { get; set; }

        [Required]
        [StringLength(50)]
        public string ProjectName { get; set; }

        public int ProjectManager { get; set; }

        public bool IsDebitable { get; set; }

        [StringLength(50)]
        public string Customer { get; set; }

        public decimal EstimatedTotalHours { get; set; }

        [Column(TypeName = "date")]
        public DateTime ProjectStart { get; set; }

        [Column(TypeName = "date")]
        public DateTime? ProjectEnd { get; set; }

        public virtual User User { get; set; }

        public virtual ICollection<TimesheetEntry> TimesheetEntries { get; set; }

        public virtual ICollection<UserProject> UserProjects { get; set; }
    }

查看：

@model Aviato.ViewModel.ListModel
<table class="table">
    @foreach (var item in Model.StaffModelList)
    {
        <tr>
            <td>@item.Flex.User.UserId</td>
            <td>@item.Flex.FlexTime</td>
            <td>@item.Flex.User.SocialSecurityNumber</td>
            <td>@item.Flex.User.FirstName</td>
            <td>@item.Flex.User.LastName</td>
            <td>@item.Flex.User.Address1</td>
            <td>@item.Flex.User.ZipCode</td>
            <td>@item.Flex.User.City</td>
            <td>@item.Flex.User.PhoneNumber1</td>
            <td>@item.Flex.User.EmploymentStartDate</td>
            <td>@item.Flex.User.Password</td>

            @foreach (var items in item.Projects)
            {
                <td>@items.ProjectId</td>
                <td>@items.ProjectName</td>
                <td>@items.ProjectManager</td>
                <td>@items.IsDebitable</td>
                <td>@items.Customer</td>
                <td>@items.EstimatedTotalHours</td>
                <td>@items.ProjectStart</td>
                <td>@items.ProjectEnd</td>
            }
        </tr>
        @Html.ActionLink("Edit", "Edit", new { id = item.Flex.User.UserId })
        @Html.ActionLink("Delete", "Delete", new { id = item.Flex.User.UserId })
    }
</table>

控制器：

private readonly AviatoModel _db = new AviatoModel(); //Database

public ActionResult Index()
{
    var projects = _db.Projects.ToList();
    var users = _db.Users.Where(u => u.Projects == projects).ToList(); //Where the Error occurs if I use: "ToList();"
    var model = new ListModel();
    var flexModel = new FlexModel();

    model.StaffModelList = new List<StaffModel>();

    foreach (var u in users) //Where the Error occurs if I dont use: "ToList();"
    {
        var staffModel = new StaffModel();

        staffModel.Projects = projects;
        staffModel.Flex = flexModel;
        staffModel.Flex.User = u;
        staffModel.Flex.FlexTime = GetFlex.Flex(u.UserId);
        model.StaffModelList.Add(staffModel);
    }

    return View(model);
}

请帮帮我......

Answer 1

这是你的问题：

var projects = _db.Projects.ToList();
    var users = _db.Users.Where(u => u.Projects == projects).ToList(); //Where the Error occurs if I use: "ToList();"

而是尝试：

var users = _db.Projects.Select(p => p.User).Distinct();

Answer 2

将您的操作更改为此。这样，无论用户是否有任何项目，您都可以获得所有用户。

public ActionResult Index()
{    
   var users = _db.Users.Include("Projects").ToList();

   var model = new ListModel();
   var flexModel = new FlexModel();

   model.StaffModelList = new List<StaffModel>();

   foreach (var u in users)
   {
       var staffModel = new StaffModel();

       staffModel.Projects.AddRange(u.Projects); //These are user specific projects. If there are no projects assigned to user, this list will be empty.
       staffModel.Flex = flexModel;
       staffModel.Flex.User = u;
       staffModel.Flex.FlexTime = GetFlex.Flex(u.UserId);
       model.StaffModelList.Add(staffModel);
   }

    return View(model);
}

无法创建类型＆＃39;的常量值。在此上下文中仅支持基元类型或枚举类型。 ASP.NET MVC LINQ EF

2 个答案: