mongo aggregation of sample data

db.input.aggregate([
	{
		$unwind: "$attributes"
	},
	{
		$lookup: {
			from: "input",
			localField: "attributes.id",
			foreignField: "attributeId",
			as: "attribute"
		}
	},
	{
		$addFields: {
			"attribute.value": "$attributes.value"
		}
	},
	{
		$project: {
			"attributes": 0
		}
	},
	{
		$unwind: "$attribute"
	},
	{
		$group: {
			_id: "$_id",
			type: {
				"$first": "$type"
			},
			productId: {
				"$first": "$productId"
			},
			attributes: {
				"$addToSet": "$attribute"
			}
		}
	}
])