将 Dictionary<long, VALUE> 序列化为 BSON 文档

Serialize Dictionary<long, VALUE> to BSON documents

我想将 Dictionary<long, VALUE> 序列化到 MongoDB 中的 JSON 之后。

{
   "213" : {},
   "63624" : {},
   ...
}

除了DictionaryRepresentation.Document.Document

我不想要其他DictionaryRepresentation

我使用的是MongoDB C# Driver (v2.0.1.27),将long类型的key转成string不智能,导致异常。

您可以使用现有的序列化程序执行此操作,但它需要少量配置。

假设以下 class:

public class C
{
    public int Id { get; set; }
    public Dictionary<long, long> D { get; set; }
}

您可以为 D 属性(字典)配置自定义序列化程序,该序列化程序使用将 long 序列化为字符串的密钥序列化程序。代码如下所示:

BsonClassMap.RegisterClassMap<C>(cm =>
{
    cm.AutoMap();
    var customDictionarySerializer = new DictionaryInterfaceImplementerSerializer<Dictionary<long, long>>(
        dictionaryRepresentation: DictionaryRepresentation.Document,
        keySerializer: new Int64Serializer(BsonType.String),
        valueSerializer: BsonSerializer.SerializerRegistry.GetSerializer<long>());
    cm.GetMemberMap(c => c.D).SetSerializer(customDictionarySerializer);
});

这里的关键思想是即使键和值都是 long,我们对键和值使用不同的序列化器。

如果我们然后 运行 快速测试:

var document = new C { Id = 1, D = new Dictionary<long, long> { { 2, 3 } } };
var json = document.ToJson();
Console.WriteLine(json);

我们看到字典键现在被序列化为字符串:

{ "_id" : 1, "D" : { "2" : NumberLong(3) } }

我也想出了一个办法,希望对其他人有帮助

public class LongDictionarySerializer<K> : DictionarySerializerBase<Dictionary<long, K>>
{
    public LongDictionarySerializer() : base(DictionaryRepresentation.Document)
    {
    }

    protected override Dictionary<long, K> CreateInstance()
    {
        return new Dictionary<long, K>();
    }

    public override void Serialize(BsonSerializationContext context, BsonSerializationArgs args, Dictionary<long, K> value)
    {
        if (value != null)
        {
            Dictionary<string, K> dic = value.ToDictionary(d => d.Key.ToString(), d => d.Value);
            BsonSerializer.Serialize<Dictionary<string, K>>(context.Writer, dic);
        }
        else
            BsonSerializer.Serialize<object>(context.Writer, null);
    }
    public override Dictionary<long, K> Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
    {
        Dictionary<string, K> dic = BsonSerializer.Deserialize<Dictionary<string, K>>(context.Reader);
        if (dic == null)
            return null;

        Dictionary<long, K> ret = new Dictionary<long, K>();
        foreach( var pair in dic )
        {
            long key;
            if (!long.TryParse(pair.Key, out key))
                continue;
            ret[key] = pair.Value;
        }
        return ret;
    }
}

然后在场上

[BsonElement(Fields.Markets)]
[BsonSerializer(typeof(LongDictionarySerializer<XXX>))]
public Dictionary<long, XXX> Markets { get; set; }