data fetching in fluent about fluent HOT 3 CLOSED

class Post: Entity {
    var id: String?
    var title: String
    var body: String
    lazy var user: ManyToOne<Post, User> = ManyToOne(self, key: "user_id")

    required init(unboxer: Unboxer) {
        id    = unboxer.unbox("id")
        title = unboxer.unbox("title")
        body  = unboxer.unbox("body")
    }
}

class User: Entity {
    var id: String?
    var name: String
    lazy var posts: OneToMany<User, Post> = OneToMany(self, reverseKey: "user_id")

    required init(unboxer: Unboxer) {
        id    = unboxer.unbox("id")
        name  = unboxer.unbox("name")
    }
}

// Entity.swift
extension Entity {
    func belongsTo<T: Entity>(_ entityType: T.Type) -> T {
        let key = String(entityType) // let's just use convention for determining the key
        return Query(entityType).someQueryToRetrieveRelatedEntity()
    }
}

// Post.swift
class Post: Entity {
    var id: String?
    var title: String
    var body: String
    lazy var user: User = self.belongsTo(User)

    required init(unboxer: Unboxer) {
        id    = unboxer.unbox("id")
        title = unboxer.unbox("title")
        body  = unboxer.unbox("body")
    }
}

class Post: Entity {
    var id: String?
    var title: String
    var body: String
    lazy var user: User = self.belongsTo(User)

    required init(unboxer: Unboxer) {
        id    = unboxer.unbox("id")
        title = unboxer.unbox("title")
        body  = unboxer.unbox("body")

        if let user: User = unboxer.unbox("user") {
            self.user = user
            // Because we initialized user here, the belongsTo() method is not executed.
            // Which means we can support eager loading and avoid the n+1 problem! :-D
        }
    }
}