我正在这样做,所以我可以从我的api返回更多基本类。
我可以使用“静态隐式运算符”语法使我可以将自定义类从一种类型转换为另一种类型,但是我一次只能这样做。使用列表时如何转换自定义类型?这是该类的Entity Framework Core版本:
public class DivDbUser : DivDbBase, IDivDbTrackable
{
[Required]
[MaxLength(256)]
public string Name { get; set; }
[Required]
[MaxLength(256)]
public string Email { get; set; }
[Key]
public int Id { get; set; }
[Required]
public DateTimeOffset DateCreated { get; set; }
public int CreatedByUserId { get; set; }
[Required]
public DateTimeOffset LastDateModified { get; set; }
public int LastModifiedByUserId { get; set; }
[ForeignKey("CreatedByUserId")]
public DivDbUser CreatedByUser { get; set; }
[ForeignKey("LastModifiedByUserId")]
public DivDbUser LastModifiedByUser { get; set; }
public ICollection<DivDbResourceAssignment> ResourceAssignments { get; set; }
public ICollection<DivDbUserRole> UserRoles { get; set;
}
这是我想为自己的api响应列表的类的基本版本:
public class DivUser : DivBase
{
public int Id { get; set; }
public string Name { get; set; }
public string Email { get; set; }
public DateTimeOffset DateCreated { get; set; }
public int CreatedByUserId { get; set; }
public DateTimeOffset LastDateModified { get; set; }
public int LastModifiedByUserId { get; set; }
public static implicit operator DivUser(DivDbUser dbUser)
{
DivUser user = new DivUser() {
Id = dbUser.Id,
Name = dbUser.Name,
Email = dbUser.Email,
DateCreated = dbUser.DateCreated,
CreatedByUserId = dbUser.CreatedByUserId,
LastDateModified = dbUser.LastDateModified,
LastModifiedByUserId = dbUser.LastModifiedByUserId
};
return user;
}
}
我一次可以投射一个,然后循环:
dbUsers = mContext.Users.ToList();
List<DivUser> users = new List<DivUser>();
foreach(DivDbUser dbUser2 in dbUsers)
{
DivUser user = dbUser2;
users.Add(user);
}
但是我想这样做:
dbUsers = mContext.Users.ToList();
List<DivUser> users = dbUsers.Cast<DivUser>().ToList();
但是当我尝试运行它时,出现以下转换错误:
System.InvalidCastException:'无法将类型为'Db.Models.DivDbUser'的对象转换为类型为'ApiModels.DivUser'。'
尽管语法相同,但转换不是强制转换,因此无法正常工作。
通过进行转换,您正在创建一个完整的新对象,而强制转换只是更改现有对象的数据类型。
尝试在Select
中进行转换:
dbUsers = mContext.Users.ToList();
List<DivUser> users = dbUsers.Select(u => (DivUser)u).ToList();