No aggregation lookup at v 6.0.1

[JoachimM7]

There seems to be a change in the API in v. 6.0.0 (I have to use the beta, because in my project I use SwiftNIO 2.8.0). Why is there a change back to AggregateBuilderStage?

I can live with it, but now there is no lookup in the aggregation possible anymore. Or do I overlook sth.?

[Joannis Orlandos]

Hello @Lupurus we do intend to reintroduce it, but we're very unsure what we want the API to look like.

[JoachimM7]

Hey, thanks for that fast answer. Any idea how I can get it back for the moment?

I liked the API from > 5.0.0, but if I look to the MongoDB documentation, the new API with AggregateBuilderStage seems to be more consequent!

[Joannis Orlandos]

You can make custom stages

[JoachimM7]

Yes, I found it out so far. Because there is no documentation, it's not quite easy to continue ;) How do I do this?

let pipeline = self.db.aggregate([
	AggregateBuilderStage(document: ["$match": "{ username: \"\(auth.username)\" }"])
])

pipeline.execute().whenComplete { result in
	print(result)
}

This gives me: failure(Couldn't find type Cursor at path "["cursor"]")

[JoachimM7]

Ok, I found it out. Should be:

AggregateBuilderStage(document: ["$match": ["username": auth.username]])

[JoachimM7]

And by the way for everyone who needs this right now, I made an extension. @Joannis: mabye you could use this as well in the final code?

extension AggregateBuilderStage {
	static func lookup(from: String, localField: String, foreignField: String, as newName: String) -> AggregateBuilderStage {
		return AggregateBuilderStage(document: [
			"$lookup": [
				"from": from,
				"localField": localField,
				"foreignField": foreignField,
				"as": newName
			]
		])
	}
	
	static func unwind(fieldPath: String, includeArrayIndex: String? = nil, preserveNullAndEmptyArrays: Bool? = nil) -> AggregateBuilderStage {
		var d = Document()
		d["path"] = fieldPath
		
		if let incl = includeArrayIndex {
			d["includeArrayIndex"] = incl
		}
		
		if let pres = preserveNullAndEmptyArrays {
			d["preserveNullAndEmptyArrays"] = pres
		}
		
		return AggregateBuilderStage(document: ["$unwind": d])
	}
}

[Joannis Orlandos]

Oh yeah, we can totally use this! That API looks nice