Latitude & Longitude misplacement of decoding ParsePolygon.

[nomoneynohoney]

New Issue Checklist

• I am not disclosing a vulnerability.
• I have searched through existing issues.
• I can reproduce the issue with the latest versions of Parse Server and the Parse Swift SDK.

Issue Description

Latitude & Longitude misplacement of decoding ParsePolygon: The order of the element in polygon is [lat, lon], the current decoding order is misplacement. The error is found at ParsePolygon: 108.

Steps to reproduce

Use [[25.1234, 121.4567], [24.321, 121.1234], [22.11, 101.321]] as test polygon data in database. Caused a decoding error.

Actual Outcome

error.

Expected Outcome

a sequence of GeoPoint.

Environment

5.7.0

Client

• Parse Swift SDK version: 5.7.0
• Xcode version: 14.3.1
• Operating system (iOS, macOS, watchOS, etc.): macOS
• Operating system version: 13.4

Server

• Parse Server version: 6.2.0
• Operating system: Ubuntu 20.04 LTS
• Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): Linode

Database

• System (MongoDB or Postgres): MongoDB
• Database version: 6.0.6
• Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): Linode

Logs

[cbaker6]

Can you post the actual error returned from the server.

What happens when you run the Playground code?

Parse-Swift/ParseSwift.playground/Pages/1 - Your first Object.xcplaygroundpage/Contents.swift

Lines 398 to 415 in 57ccb4b

	//: How to add `ParseBytes` and `ParsePolygon` to objects.
	let points = [
	try ParseGeoPoint(latitude: 0, longitude: 0),
	try ParseGeoPoint(latitude: 0, longitude: 1),
	try ParseGeoPoint(latitude: 1, longitude: 1),
	try ParseGeoPoint(latitude: 1, longitude: 0),
	try ParseGeoPoint(latitude: 0, longitude: 0)
	]
	do {
	let polygon = try ParsePolygon(points)
	let bytes = ParseBytes(data: "hello world".data(using: .utf8)!)
	var gameData = GameData(bytes: bytes, polygon: polygon)
	gameData = try await gameData.save()
	print("Successfully saved: \(gameData)")
	} catch {
	print("Error saving: \(error.localizedDescription)")
	}

[nomoneynohoney]

ParsePolygon.swift, line: 108. the order of a point in the polygon should be [lat, lon].

[nomoneynohoney]

There won't be error, because the value is decodable. but the order is misplaced, so if u really generate a sequence of coordinates, save into db, then use ParseSwift to decode it and place them back on map. you will find the error.

[cbaker6]

There won't be error, because the value is decodable. but the order is misplaced, so if u really generate a sequence of coordinates, save into db, then use ParseSwift to decode it and place them back on map. you will find the error.

You stated it caused a decoding error, this is the error I was referring to:

Use [[25.1234, 121.4567], [24.321, 121.1234], [22.11, 101.321]] as test polygon data in database. Caused a decoding error.

My tests show that the current implementation is correct (for Postgres and Mongo). The server needs ParsePolygon coordinates to be encoded as (longitude, latitude), not (latitude, longitude) in order to use ParsePolygon for queries and saved objects. On the other hand, when using ParseGeoPoint's directly, the server needs encoding (latitude, longitude). When you decode ParsePolygon it should always decode properly to latitude and longitude for each ParseGeoPoint. All of this can be seen in parse-community/parse-server#4607 and the server-side tests:

• https://github.com/parse-community/parse-server/blob/4ad08005086b86ea46ef7567513a212454074804/spec/ParsePolygon.spec.js#L499-L531
• https://github.com/parse-community/parse-server/blob/4ad08005086b86ea46ef7567513a212454074804/spec/MongoTransform.spec.js#L77-L123

I've updated the Playground examples so you can run them directly to test what I mentioned above:

Parse-Swift/ParseSwift.playground/Pages/7 - GeoPoint.xcplaygroundpage/Contents.swift

Lines 68 to 113 in 80347b7

	//: Define initial GameScore.
	var score = GameScore(points: 10)
	do {
	try score.location = ParseGeoPoint(latitude: 40.0, longitude: -30.0)
	let points: [ParseGeoPoint] = [
	try .init(latitude: 35.0, longitude: -30.0),
	try .init(latitude: 42.0, longitude: -35.0),
	try .init(latitude: 42.0, longitude: -20.0)
	]
	score.polygon = try ParsePolygon(points)
	}
	/*:
	Save asynchronously with completion block - performs work on background
	queue and returns to specified callbackQueue.
	If no callbackQueue is specified it returns to main queue.
	*/
	score.save { result in
	switch result {
	case .success(let savedScore):
	assert(savedScore.objectId != nil)
	assert(savedScore.createdAt != nil)
	assert(savedScore.updatedAt != nil)
	assert(savedScore.points == 10)
	assert(savedScore.location != nil)
	assert(savedScore.polygon != nil)
	guard let location = savedScore.location else {
	print("Something went wrong")
	return
	}
	print("Saved location: \(location)")
	guard let polygon = savedScore.polygon else {
	print("Something went wrong")
	return
	}
	print("Saved polygon: \(polygon)")
	print("Saved polygon geopoints: \(polygon.coordinates)")
	case .failure(let error):
	assertionFailure("Error saving: \(error)")
	}
	}

Which results in the following output:

# Postgres
Saved location: {"__type":"GeoPoint","latitude":40,"longitude":-30}
Saved polygon: {"__type":"Polygon","coordinates":[[-30,35],[-35,42],[-20,42]]}
Saved polygon geopoints: [{"__type":"GeoPoint","latitude":35,"longitude":-30}, {"__type":"GeoPoint","latitude":42,"longitude":-35}, {"__type":"GeoPoint","latitude":42,"longitude":-20}]

# Mongo
Saved location: {"__type":"GeoPoint","latitude":40,"longitude":-30}
Saved polygon: {"__type":"Polygon","coordinates":[[-30,35],[-35,42],[-20,42]]}
Saved polygon geopoints: [{"__type":"GeoPoint","latitude":35,"longitude":-30}, {"__type":"GeoPoint","latitude":42,"longitude":-35}, {"__type":"GeoPoint","latitude":42,"longitude":-20}]

The following test was improved to ensure all of the aforementioned is maintained:

Parse-Swift/Tests/ParseSwiftTests/ParsePolygonTests.swift

Lines 77 to 88 in 2688192

	func testEncode() throws {
	let polygon = try ParsePolygon(points)
	let expected = "{\"__type\":\"Polygon\",\"coordinates\":[[0,0],[1,0],[1,1],[0,1],[0,0]]}"
	XCTAssertEqual(polygon.debugDescription, expected)
	guard polygon.coordinates.count == points.count else {
	XCTAssertEqual(polygon.coordinates.count, points.count)
	return
	}
	for (index, coordinates) in polygon.coordinates.enumerated() {
	XCTAssertEqual(coordinates, points[index])
	}
	}

[cbaker6]

It looks like there may be a small bug here as the server handles saved polygons and queried polygons differently. Still investigating...

See #118