LINQ to Entities不支持指定的类型成员'Title'

Question

我Title在Linq to Entity中使用属性时遇到错误:

LINQ to Entities不支持指定的类型成员'Title'.仅支持初始值设定项,实体成员和实体导航属性.

我的查询是:

        var db = FaraWorkspaceEntity.GetEntity();

        var query = from item in db.ProjectManagers
                    where item.ProjectID == projectID
                    select new UserListItem
                    {
                        ID = item.UserID,
                        Title = item.User.Title // Here is error
                    };

        return query.ToList();



    public class User : IdentityUser<string, UserLogin, UserRole, UserClaim>
    {
        [Required]
        [Display(Name = "???")]
        [StringLength(50)]
        public string Firstname { get; set; }

        [Required]
        [Display(Name = "??? ????????")]
        [StringLength(50)]
        public string Lastname { get; set; }

        public string Title
        {
            get { return this.Firstname + " " + this.Lastname; }
        }
    }

Answer 1

Title是您实体的财产.在你的表中没有这样的列.Entity Framework无法将您的代码转换为Sql.因此,您必须将代码更改为:

  var query = from item in db.ProjectManagers
              where item.ProjectID == projectID
              select new UserListItem
              {
                   ID = item.UserID,
                   Title = item.User.Firstname + " " + item.User.Lastname;
              };

但是,我建议你选择FirstName和LastName,当你想获得Title你的getter访问器的价值时会起作用:

  var query = from item in db.ProjectManagers
              where item.ProjectID == projectID
              select new UserListItem
              {
                   ID = item.UserID,
                   Firstname = item.User.Firstname
                   Lastname =  item.User.Lastname;
              };