我将用户配置文件保存在DynamoDB中，并使用属性将.net类型转换为dynamo条目
这是我使用的转换器

public class DictRoomClassHouseInfoConverter : IPropertyConverter
{
    ...

    public DynamoDBEntry ToEntry(object value)
    {
        var dictionary = value as Dictionary<RoomClass, HouseInfo>;

        if (dictionary == null)
        {
            throw new ArgumentException("Invalid type");
        }

        var entry = new PrimitiveList();

        foreach (var kvp in dictionary)
        {
            entry.Add(new Primitive { Value = string.Format("{0}|{1}|{2}", (int)kvp.Key, kvp.Value.House, kvp.Value.TimesSold) });
        }

        return entry;
    }
}

现在的问题是，当字典为空并且ToEntry返回空的PrimitiveList时，将不保存对该字典的更改
所以如果我这样做：

var profile = GetProfile(id);
//profile.DictProp has 3 items; 

profile.DictProp.Clear();
//profile.DictProp has 0 items;

SaveProfile(profile);

var p = GetProfile(id);
//profile.DictProp has 3 items;