MongoDB Quickies

JToken.cs

private void Flatten(JToken token, IDictionary<string, JValue> output, string prefix = "")
{
	if (token is JObject jObj)
	{
		foreach(var item in token)
		{
			Flatten(item, output, prefix);
		}
	} else if (token is JArray jArr)
	{
		for (var i = 0; i < jArr.Count; i++)
		{
			var item = jArr[i];
			Flatten(item, output, prefix + "." + "$" + i.ToString());
		}
	} else if (token is JProperty jProp)
	{
		if (prefix.Length > 0) { prefix = prefix + "."; }
		if (jProp.Value is JValue jValue) {
			output[prefix + jProp.Name] = jValue;			
		} else {			
			Flatten(jProp.Value, output, prefix + jProp.Name);
		}			
	}
}

Mongo.js

db.purchase_orders.aggregate(
    [{
            $match: {
                customer: {
                    $in: ["Mike", "Karen"]
                }
            }
        }, {
            $group: {
                _id: "$customer",
                total: {
                    $sum: "$total"
                }
            }
        }, {
            $sort: {
                total: -1
            }
        }
    ], {
    "explain": false,
    "allowDiskUse": true,
    "cursor": {
        'batchSize': 5
    }
});

db.purchase_orders.aggregate(
    [{
            $match: {}
        }, {
            $group: {
                _id: "$customer",
                total: {
                    $sum: "$total"
                }
            }
        }, {
            $sort: {
                total: -1
            }
        }
    ]);

db.purchase_orders.aggregate(
    [{
            "$group": {
                "_id": "$customer",
                "count": {
                    "$sum": 1
                }
            }
        }, {
            "$match": {
                "count": {
                    "$gte": 5
                }
            }
        }, {
            "$sort": {
                "count": -1
            }
        }
    ]);

Parser.cs

    public static class Parser
    {
        public static BsonValue ToBsonValue(this JToken token) => ParseRecursively(token);

        private static BsonValue ParseRecursively(JToken token)
        {
            switch (token)
            {
                case JObject jObj:
                    var doc = new BsonDocument();
                    foreach (var (key, value) in jObj)
                    {
                        doc[key] = ParseRecursively(value);
                    }
                    return doc;
                case JArray jArr:
                    var arr = new BsonArray();
                    foreach (var item in jArr)
                    {
                        arr.Add(ParseRecursively(item));
                    }
                    return arr;
                case JValue jVal:
                    return BsonValue.Create(jVal.Value);
                default:
                    throw new NotImplementedException();
            }
        }
    }