IComparer、OrderBy和Linq

Question

我有一个定制的比较器，我想用在OrderBy上。此比较器允许以我想要的方式对嵌套列表进行排序。我在其他地方工作得很好，但我不能让它按照我想要的方式和Linq一起工作。你能告诉我哪里错了吗？

编辑:我想让它工作的方式是首先按类对我的实体进行分组(BaseDirectory > BaseSite > VideoEntity，总是这样)，然后按字母顺序对它们进行排序(升序= A->Z或降序Z->A)。无论如何，当我使用SortDirectoriesDescending()时，将返回按升序排序的集合。默认情况下，集合是在升序模式下排序的(因此转换器可以工作，我已经测试过它是否降序，好的)

public class VideoEntityComparer : IComparer<VideoEntity>
{

    int order = 1;

    public VideoEntityComparer(Boolean ascending)
    {
        if (!ascending)
        {
            this.order = -1; // so descending
        }
    }

    public VideoEntityComparer()
    {

    }

    public int Compare(VideoEntity x, VideoEntity y)
    {
        if ((x is BaseDirectory && y is BaseDirectory) || (x is BaseSite && y is BaseSite) || (x is VideoEncoder && y is VideoEncoder))
        {
            return string.Compare(x.Nom, y.Nom, false) * order; // only objects of the same type are sorted alphabetically
        }
        else if ((x is BaseDirectory && y is BaseSite) || (x is BaseSite && y is VideoEncoder))
        {
            return -1;
        }else
        {
            return 1;
        }
    }
}

private void SortDirectoriesDescending(object sender, RoutedEventArgs e)
    {
        ObservableCollection<BaseDirectory> tempDir  = new ObservableCollection<BaseDirectory>(
            Directories.OrderBy(directory => directory, new VideoEntityComparer(false)));
        Directories = tempDir;
    }

Answer 1

尝试对您的比较方法进行以下更改：

public int Compare(VideoEntity x, VideoEntity y)
{
    if ((x is BaseDirectory && y is BaseDirectory) || (x is BaseSite && y is BaseSite) || (x is VideoEncoder && y is VideoEncoder))
    {
        return string.Compare(x.Nom, y.Nom, false) * order; // only objects of the same type are sorted alphabetically
    }
    else if ((x is BaseDirectory && y is BaseSite) || (x is BaseSite && y is VideoEncoder) || (x is BaseDirectory && y is VideoEncoder)) // Added (x is BaseDirectory && y is VideoEncoder)
    {
        return -1;
    }
    else
    {
        return 1;
    }
}

您的代码以前定义了order BaseDirectory < BaseSite和BaseSite < VideoEncoder，但是BaseDirectory > VideoEncoder，这可能会混淆OrderBy，因为排序不是传递的。