c#-在联接LINQ中使用多个条件.我和

如何在LINQ联接中使用多个条件,即在我的场景中,我需要从表User中获取所有用户,其中表ID为4,从表UserInGroup中获取,其中UserInGroup是User和Group表之间的中间表,如SQL-T如

select * 
from user 
where user.userID = userIngroup.userID AND userIngroup.groupID == 4
....

在另一种方法中,我将lambda表达式与LINQ一起使用,如何在下一个中的groupID = 4的情况下应用？

public IEnumerable<User> GetUsersByGroupID(int _groupID)
    {

        List<User> _listedUsersByGroupID = new List<User>();

        using(var _uow = new UserManagement_UnitOfWork())
        {

            _listedUsersByGroupID = (from _users in _uow.User_Repository.GetAll()
                                    .Include(s=>s.UserInGroup.Select(r=>r.Group))
                                    select _users).ToList();

            return _listedUsersByGroupID;

        }
    }

用户模型

[Table("User")]
public class User
{
    public User() { }

    [Key]
    public int UserID { get; set; }

    [StringLength(250)]
    [Required]
    public string FirstName { get; set; }

    [StringLength(250)]
    [Required]
    public string LastName { get; set; }

    [Required]
    public int Age { get; set; }

    [StringLength(250)]
    [Required]
    public string EmailAddress { get; set; }

    public ICollection<UserInGroup> UserInGroup { get; set; }
}

UserInGroup模型

 [Table("UserInGroup")]
public class UserInGroup
{
    public UserInGroup() { }

    [Key]
    public int UserGroupID { get; set; }

    [Required]
    public int UserID { get; set; }

    [Required]
    public int GroupID { get; set; }

    public User User { get; set; }
    public Group Group { get; set; }
}

组模型

public class Group
{
    public Group() { }

    [Key]
    public int GroupID { get; set; }

    [StringLength(250)]
    [Required]
    public string GroupName { get; set; }

    public ICollection<UserInGroup> UserInGroup { get; set; }
}

解决方法:

您只需要添加一个条件即可过滤属于该组4的用户.尝试执行以下操作：

  _listedUsersByGroupID = (from _user in _uow.User_Repository.GetAll()
                                    .Include(s=>s.UserInGroup.Select(r=>r.Group))
                           where user.UserInGroup.Any(ug=>ug.groupID==4)
                           select _user).ToList();

标签：repository-pattern,entity-framework-6,linq,c,asp-net-mvc
来源： https://codeday.me/bug/20191028/1951309.html