Question

我有一个查询在使用匿名类型时工作正常但是一旦我尝试取消匿名化它就无法在类中选择所有值。

这是我正在使用的linq（与Subsonic 3结合使用）：

var producten = (from p in Premy.All()
     join pr in Producten.All() on p.dekking equals pr.ID
     where p.kilometragemax >= 10000 &&
           p.CCmin < 3000 &&
           p.CCmax >= 3000 &&
           p.leeftijdmax >= DateTime.Today.Subtract(car.datumEersteToelating).TotalDays / 365
     group p by new { pr.ID, pr.Naam, pr.ShortDesc, pr.LongDesc } into d
     select new
     {
         ID = d.Key.ID,
         Dekking = d.Key.Naam,
         ShortDesc = d.Key.ShortDesc,
         LongDesc = d.Key.LongDesc,
         PrijsAlgemeen = d.Min(x => x.premie),
         PrijsAlgemeenMaand = d.Min(x => x.premie),
         PrijsMerkdealerMaand = d.Min(x => x.premie),
         PrijsMerkdealer = d.Min(x => x.premie)
     }).ToList();

当我将其更改为：

List<QuotePremies> producten = (from p in Premy.All()
     join pr in Producten.All() on p.dekking equals pr.ID
     where p.kilometragemax >= 10000 &&
           p.CCmin < 3000 &&
           p.CCmax >= 3000 &&
           p.leeftijdmax >= DateTime.Today.Subtract(car.datumEersteToelating).TotalDays / 365
     group p by new { pr.ID, pr.Naam, pr.ShortDesc, pr.LongDesc } into d
     select new QuotePremies
     {
         ID = d.Key.ID,
         Dekking = d.Key.Naam,
         ShortDesc = d.Key.ShortDesc,
         LongDesc = d.Key.LongDesc,
         PrijsAlgemeen = d.Min(x => x.premie),
         PrijsAlgemeenMaand = d.Min(x => x.premie),
         PrijsMerkdealerMaand = d.Min(x => x.premie),
         PrijsMerkdealer = d.Min(x => x.premie)
     }).ToList();

与此课程结合使用：

public class QuotePremies
{
    public byte ID { get; set; }
    public string Dekking { get; set; }
    public string ShortDesc { get; set; }

    public string LongDesc { get; set; }
    public decimal PrijsAlgemeen { get; set; }
    public decimal PrijsAlgemeenMaand { get; set; }
    public decimal PrijsMerkdealer { get; set; }
    public decimal PrijsMerkdealerMaand { get; set; }
}

它没有给我一个错误，但除了QuotePremies.ID，QuotePremies.ShortDesc和QuotePremies.LongDesc之外，该类中的所有值都是0。不知道为什么会这样。

Answer 1

查看是否使用转换帮助

PrijsAlgemeen = Convert.ToDecimal(d.Min(x => x.premie))

Answer 2

我遇到了完全相同的问题。这是Subsonic中的一个错误：SubSonic 3 Linq projecting anonymous types but not class types

Answer 3

我认为问题与铸造有关。为什么不使用IEnumberable的写入和扩展方法来获取此查询结果并返回List的集合。它可能看起来像这样：

public static class Extensions
{
    // extends IEnumerable to allow conversion to a custom type
    public static TCollection ToMyCustomCollection<TCollection, T>(this IEnumerable<T> ienum)
           where TCollection : IList<T>, new()
    {
        // create our new custom type to populate and return
        TCollection collection = new TCollection();

        // iterate over the enumeration
        foreach (var item in ienum)
        {
            // add to our collection
            collection.Add((T)item);
        }

        return collection;
    }
}

感谢kek444帮助我解决类似的问题

无法使用linq选择课程

3 个答案: