LINQ to Entities 不支持指定的类型成员 'Title'

Question

我在 Linq to Entity 中使用 Title 属性时出错：

The specified type member 'Title' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

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 = "نام")]
        [StringLength(50)]
        public string Firstname { get; set; }

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

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

Answer 1

Title 是您实体中的属性。在您的 table 中没有这样的栏目。 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 select FirstName 和 LastName，当你想获得 Title 的值时，你的 getter 访问器将工作：

  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;
              };

LINQ to Entities 不支持指定的类型成员 'Title'

The specified type member 'Title' is not supported in LINQ to Entities

c#

linq

entity-framework

ef-code-first