Question

我从我的实体框架中有这个类，我想在列表中存储我的linq查询的结果，以便在我的网页表单中显示它，我收到此错误消息：

错误4无法隐式转换类型 'System.Collections.Generic.List'到 'System.Collections.Generic.List'\ App_Code \ Models \ PackageModel.cs

这是我的代码：

感谢您的帮助。

public partial class Package
{
    public int ID { get; set; }
    public int SchoolID { get; set; }
    public int SessionID { get; set; }
    public int LessonsID { get; set; }
    public virtual Lesson Lesson { get; set; }
    public virtual School School { get; set; }
    public virtual Session Session { get; set; }
}

public List<Package> GetAllItemPackage()
{
    try
    {
        using (MusicSchoolEntities db = new MusicSchoolEntities())
        {
            List<Package> packages = (from x in db.Packages                                           
                                      join y in db.Schools on x.SchoolID equals y.ID
                                      join z in db.Sessions on x.SessionID equals z.ID
                                      join w in db.Lessons on x.LessonsID equals w.ID
                                      join q in db.Courses on w.CourseID equals q.ID
                                      select new { SchoolTitle = y.TitleEn , 
                                                   SessionName = z.NameEn, 
                                                   CourseTitle = q.TitleEn, 
                                                   LessonPeriod = w.PeriodEn, 
                                                   LessonPrice = w.PriceEn, 
                                                   LessonDesc = w.DescriptionEn, 
                                                   LessonPaymtd = w.PayMtdEn}).ToList();
                return packages;
            }
        }

        catch (Exception)
        {
            return null;
        }
    }

Answer 1

那里有2个问题。

首先，您的代码返回匿名类型，但您正在尝试填充List<Package> - 这就是你得到例外的原因。
其次，您尝试填充的数据与您拥有的Package类不同，如果您想从函数返回此类列表，则应创建新类型class 拥有所有这些属性。

所以：

List<YourClass> packages = (from x in db.Packages                                           
                          join y in db.Schools on x.SchoolID equals y.ID
                          join z in db.Sessions on x.SessionID equals z.ID
                          join w in db.Lessons on x.LessonsID equals w.ID
                          join q in db.Courses on w.CourseID equals q.ID
                          select new YourClass
                          {
                              SchoolTitle = y.TitleEn , 
                              SessionName = z.NameEn, 
                              CourseTitle = q.TitleEn, 
                              LessonPeriod = w.PeriodEn, 
                              LessonPrice = w.PriceEn, 
                              LessonDesc = w.DescriptionEn, 
                              LessonPaymtd = w.PayMtdEn
                          }).ToList();
return packages;

当然GetAllItemPackage应该返回：List<YourClass>而不是List<Package>

将Linq查询存储在列表c＃中

1 个答案: