Mongodb C# -如何按多个字段分组(聚合)

using MongoDB.Bson;
using MongoDB.Driver;

var client = new MongoClient("mongodb://localhost:27017");
var database = client.GetDatabase("your_database_name");
var collection = database.GetCollection<BsonDocument>("your_collection_name");

var pipeline = new BsonDocument[]
{
    new BsonDocument("$group", new BsonDocument
    {
        { "_id", new BsonDocument
            {
                { "field1", "$field1" },
                { "field2", "$field2" }
            }
        },
        { "count", new BsonDocument("$sum", 1) }
    })
};

var result = collection.Aggregate<BsonDocument>(pipeline).ToList();