Question

我正在努力在我的LiteDB数据库中插入/更新带有对象列表的类的类。我尝试了几种方法和可能的解决方案，但无法使其正常工作。

这是我的课程：

父母：

 [BsonRef("pictogram")]
public class Pictogram : BasePictogram, IPictogram
{
      /// <summary>
    /// each pictogram has an unique Id
    /// the Id tpye is Guid
    /// </summary>
    [BsonId]
    public Guid Id { get; }

    /// <summary>
    /// The 2D Array (list of list) which contain the whole matrix of Pixels in it
    /// </summary>°
    public List<List<IPixel>> Pixels { get; set; }
}

孩子：

enter code [BsonRef("pixel")]
public class Pixel : IPixel
{
    [BsonId]
    public Guid Id { get; set; }

    /// <summary>
    /// the X coordinate of the pixel
    /// </summary>
    public int X { get; set; }

    /// <summary>
    /// the Y coordinate of the pixel
    /// </summary>
    public int Y { get; set; }

    /// <summary>
    /// the color of the pixel
    /// </summary>
    public Color Color { get; set; }

    /// <summary>
    /// defines if the pixel was set from a text or a graphic object
    /// </summary>
    public PixelSource PixelSource { get; set; }
}

我尝试通过BsonMapper映射这些集合：

   public void InsertPictogram(Pictogram pic)
    {
        var mapper = BsonMapper.Global;

        mapper.Entity<Pictogram>()
            .DbRef(p => p.Pixels, "pixel");

        if (pic == null) throw new ArgumentNullException(nameof(pic));
        using (var db = new LiteDatabase(_connectionString))
        {
            var pictograms = db.GetCollection<Pictogram>("pictogram");
            var pixels = db.GetCollection<IPixel>("pixel");


            foreach (var pixel in pic.Pixels.ToList())
            {
                pixels.Insert(pixel);
            }

            pictograms.Insert(pic);

        }
    }

但是当我尝试插入图片时，我得到了nullReferenceException。

有人可以解释我如何正确使用LiteDB中的列表列表吗？

非常感谢！ BR史蒂夫

Answer 1

象形图在插入图片时不为空-> pictograms.Insert（pic）;

它是LiteCollection的实例：

pictograms={LiteDB.LiteCollection<PiktogrammManager.Model.Pictogram>}
Name="pictogram"
Visitor={LiteDB.QueryVisitor<PiktogrammManager.Model.Pictogram>}
_autoId=Guid
_engine={LiteDB.LiteEngine}
_id={LiteDB.MemberMapper}
_includes=Count = 0
_log={LiteDB.Logger}
_mapper={LiteDB.BsonMapper}
_name="pictogram"
_visitor={LiteDB.QueryVisitor<PiktogrammManager.Model.Pictogram>}

LiteDB如何插入对象列表列表

1 个答案: