Given the example from the vapor docs:
// Example of a pivot model.
final class PlanetTag: Model {
static let schema = "planet tag"
@ID(key: .id)
var id: UUID?
@Parent(key: "planet_id")
var planet: Planet
@Parent(key: "tag_id")
var tag: Tag
init() { }
init(id: UUID? = nil, planet: Planet, tag: Tag) throws {
self.id = id
self.$planet.id = try planet.requireID()
self.$tag.id = try tag.requireID()
}
}
final class Planet: Model {
// Example of a siblings relation.
@Siblings(through: PlanetTag.self, from: \.$planet, to: \.$tag)
public var tags: [Tag]
}
final class Tag: Model {
// Example of a siblings relation.
@Siblings(through: PlanetTag.self, from: \.$tag, to: \.$planet)
public var planets: [Planet]
}
How can I query with fluent all planets which do not have a tag?
Planet.query(on: req.db).filter(?).all()
EDIT: Solution but with async/await
let pivots = try await PlanetTag.query(on: req.db).unique().all()
let planetsWithTags = pivots.map { $0.$planet.id }
let planetsWithoutTags = Planet.query(on: req.db).filter(\.$id !~ planetsWithTags)
return try await planetsWithoutTags.paginate(for: req).map(\.detail)
CodePudding user response:
I haven't checked this out but, intuitively, this should work if you want to make use of the Sibling
relationship:
Planet.query(on:req.db).with(\.$tags).all().map { allPlanets in
let planetWithoutTags = allPlanets.filter { $0.tags.isEmpty }
// continue processing
}
This is a bit wasteful, since you are fetching (potentially) lots of records that you don't want. A better approach is to get the planets that do have tags and then exclude those:
PlanetTag.query(on:req.db).unique().all(\.$planet).flatMap { planetTags in
return Planet.query(on:req.db).filter(\.$id !~ planetTags.map { $0.$planet.$id }).all().flatMap { planetsWithoutTags in
// continue processing
}
}