无法将类型为'System.Linq.GroupedEnumerable'的对象强制转换为'System.Collections.Generic.List

Question

我有一个这样的课.

 public static SkillViewModel GetAllList(string ID)
{
    ListViewModel viewModel = new ListViewModel();
    DataTable dt = DAL.GetAllList(ID);

    List<Skill> skills = new List<Skill>();
    foreach (DataRow row in dt.Rows)
    {
        Skill skill = new Skill() { GroupName = row["GroupName"] != null ? row["GroupName"].ToString() : string.Empty, SubName = row["SubName"] != null ? row["SubName"].ToString() : string.Empty};
        skills.Add(skill);
    }
    viewModel.skills = skills;
    viewModel.skills = skills.GroupBy(x => x.GroupName);  //Showing error in this line
   return viewModel;

}

另一个像这样:

 public class SkillViewModel
  {
    public List<Skill> skills { get; set; }
  }

  public class Skill
{
    [DisplayName("Sub Name")]
    [Required]
    public string SubName { get; set; }

    [DisplayName("Group Name")]
    [Required]
    public string GroupName { get; set; }
}

但是说它失败了

错误:无法将类型'System.Collections.Generic.IEnumerable>'隐式转换为'System.Collections.Generic.List'.存在显式转换(您是否错过了演员？)

请帮忙.提前致谢.

Answer 1

只需添加ToList与SelectMany在类似语句的结尾:

viewModel.skills = skills.GroupBy(x => x.GroupName).SelectMany(r => r).ToList();

使用SelectMany会弄平群组,不确定为什么要对数据进行分组,而你的属性却是List<Skill>