BsonClassMapSerializer 已经注册了 AbstractClassSerializer

Question

我正在使用 Mongo c# 驱动程序 2.0，并且在为我的 Id 值对象注册 AbstractClassSerializer 时运行遇到 BsonSerializer 注册问题。

MongoDB.Bson.BsonSerializationException: There is already a serializer registered for type HistoricalEventId.

当我查看 BsonSerializer 时，我看到 BsonClassMapSerializer 已经为我的类型注册了。

我假设正在为我的实体类型创建一个 BsonClassMapSerializer，它还为 Id 字段创建一个 BsonClassMapSerializer。有人运行以前参与过这个吗？如果有帮助，Bson 序列化程序代码如下所示。

抱歉，如果格式有误，C# 似乎显示不佳。

HistoricalEventIdBsonSerializer

public class HistoricalEventIdBsonSerializer : ToObjectIdBsonSerializer<HistoricalEventId>
{
    public override HistoricalEventId CreateObjectFromObjectId(ObjectId serializedObj)
    {
        HistoricalEventId parsedObj;
        HistoricalEventId.TryParse(serializedObj, out parsedObj);
        return parsedObj;
    }
}

ToObjectIdBsonSerializer

public abstract class ToObjectIdBsonSerializer<T> : AbstractClassSerializer<T> where T : class
{
    private static readonly Type _convertibleType = typeof(IConvertible<ObjectId>);
    public abstract T CreateObjectFromObjectId(ObjectId serializedObj);

    public override T Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
    {
        var bsonType = context.Reader.GetCurrentBsonType();
        ObjectId value;
        switch (bsonType)
        {
            case BsonType.Undefined:
                value = ObjectId.Empty;
                context.Reader.ReadUndefined();
                break;
            case BsonType.Null:
                value = ObjectId.Empty;
                context.Reader.ReadNull();
                break;
            case BsonType.ObjectId:
                value = context.Reader.ReadObjectId();
                break;
            case BsonType.String:
                value = new ObjectId(context.Reader.ReadString());
                break;
            default:
                throw new NotSupportedException("Unable to create the type " + 
                    args.NominalType.Name + " from the bson type " + bsonType + ".");
        }
        return this.CreateObjectFromObjectId(value);
    }

    public override void Serialize(BsonSerializationContext context, BsonSerializationArgs args, T value)
    {
        if (value == null)
        {
            context.Writer.WriteObjectId(ObjectId.Empty);
        }
        else
        {
            if (!_convertibleType.IsAssignableFrom(args.NominalType))
            {
                throw new NotSupportedException("The type " + args.NominalType.Name + 
                    " must implement the " + _convertibleType.Name + " interface.");
            }
            var typedObj = (IConvertible<ObjectId>)value;
            context.Writer.WriteObjectId(typedObj.ToValueType());
        }
    }

}

IConvertible

public interface IConvertible<out T>
{
    T ToValueType();
}

Answer 1

我的假设一定是正确的，因为我只是在创建 MongoClient 和获取数据库之前通过注册 BsonSerializer 来解决这个问题。希望这会对其他人有所帮助。

BsonClassMapSerializer 已经注册了 AbstractClassSerializer

BsonClassMapSerializer already registered for AbstractClassSerializer

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