我有四个简单的类

public class Zoo{
    public ObjectId Id { get; set; } 
    public List<Animal> Animals { get; set; }
}
public class Animal{
    public ObjectId Id { get; set; } 
    public string Name { get; set; } 
}
public class Tiger : Animal{
    public double Height { get; set; }
}
public class Zebra : Animal{
    public long StripesAmount { get; set; }
}

我创建了自定义序列化程序，它允许我将 Animal 对象存储在不同的集合(“动物”)中。

class MyAnimalSerializer : SerializerBase<Animal>
{
    public override void Serialize(MongoDB.Bson.Serialization.BsonSerializationContext context, MongoDB.Bson.Serialization.BsonSerializationArgs args, Animal value)
    {
        context.Writer.WriteStartDocument();
        context.Writer.WriteName("_id");
        context.Writer.WriteObjectId(ObjectId.GenerateNewId());
        context.Writer.WriteName("_t");
        context.Writer.WriteString(value.GetType().Name);
        context.Writer.WriteName("Name");
        context.Writer.WriteString(value.Name);
        switch (value.AnimalType)
        {
            case AnimalType.Tiger:
                context.Writer.WriteName("Height");
                context.Writer.WriteDouble((value as Tiger).Height);
                break;
            case AnimalType.Zebra:
                context.Writer.WriteName("StripesAmount");
                context.Writer.WriteInt32((value as Zebra).StripesAmount);
                break;
            default:
                break;
        }
        context.Writer.WriteEndDocument();
    }

    public override Animal Deserialize(MongoDB.Bson.Serialization.BsonDeserializationContext context, MongoDB.Bson.Serialization.BsonDeserializationArgs args)
    {
        context.Reader.ReadStartDocument();

        ObjectId id = context.Reader.ReadObjectId();
        string object_type = context.Reader.ReadString();
        string animal_name = context.Reader.ReadString();
        switch (object_type) 
        {
            case "Tiger":
                double tiger_height = context.Reader.ReadDouble();
                context.Reader.ReadEndDocument();
                return new Tiger()
                {
                    Id = id,
                    Name = animal_name,
                    Height = tiger_height
                };
            default:
                long zebra_stripes = context.Reader.ReadInt64();
                context.Reader.ReadEndDocument();
                return new Zebra()
                {
                    Id = id,
                    Name = animal_name,
                    StripesAmount = zebra_stripes
                };
        }
        return null;
    }
}

哪个效果很好，也允许我做这样的事情:

MongoDB.Bson.Serialization.BsonSerializer.RegisterSerializer(typeof(Animal), new MyAnimalSerializer());
IMongoCollection<Animal> collection = db.GetCollection<Animal>("animals");
var lst = await collection.Find<Animal>(new BsonDocument()).ToListAsync();

但是当动物被存放在动物园时，我不能做同样的事情 并且不能从 Zoo 集合中反序列化 Zoo:

IMongoCollection<Zoo> collection = db.GetCollection<Zoo>("zoocollection");
var lst = await collection.Find<Zoo>(new BsonDocument()).ToListAsync(); //not working here

是否可以为该字段创建自定义集合序列化程序？

public List<Animal> Animals { get; set; }

谁能举个例子？ 提前致谢。

最佳答案

非常感谢Anton Putau寻求最简单的解决方案。

但是还有一个。手动序列化对象:

public class MyListAnimalSerializer : SerializerBase<List<Animals>>
{
    public override void Serialize(MongoDB.Bson.Serialization.BsonSerializationContext context, MongoDB.Bson.Serialization.BsonSerializationArgs args, List<Animal> value)
    {
        context.Writer.WriteStartArray();
        foreach (Animal mvnt in value)
        {
            context.Writer.WriteStartDocument();
            switch (mvnt.GetType().Name)
            {
                case "Tiger":
                    //your serialization here
                    break;
                case "Zebra":
                    //your serialization here
                    break;
                default:
                    break;
            }
            context.Writer.WriteEndDocument();
        }
        context.Writer.WriteEndArray();
    }

    public override List<Animals> Deserialize(MongoDB.Bson.Serialization.BsonDeserializationContext context, MongoDB.Bson.Serialization.BsonDeserializationArgs args)
    {
        context.Reader.ReadStartArray();

        List<Animals> result = new List<Animals>();

        while (true)
        {
            try
            {
                //this catch block only need to identify the end of the Array
                context.Reader.ReadStartDocument();
            }
            catch (Exception exp)
            {
                context.Reader.ReadEndArray();
                break;
            }

            var type = context.Reader.ReadString();
            var _id = context.Reader.ReadObjectId();
            var name = context.Reader.ReadString();
            if (type == "Tiger")
            {
                double tiger_height = context.Reader.ReadDouble();
                result.Add(new Tiger()
                {
                    Id = id,
                    Name = animal_name,
                    Height = tiger_height
                });
            }
            else
            {
                long zebra_stripes = context.Reader.ReadInt64();
                result.Add(return new Zebra()
                {
                    Id = id,
                    Name = animal_name,
                    StripesAmount = zebra_stripes
                });
            }
            context.Reader.ReadEndDocument();
        }
        return result;
    }
}

而且您只需注释 IEnumerable 字段即可使用您的序列化程序:

[BsonSerializer(typeof(MyListAnimalSerializer))]
public List<Animal> Animals { get; set; }

关于c# - MongoDb 自定义集合序列化器，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30421379/