I'm getting a response from an API and decoding the response like this:
struct MyStuff: Codable {
let name: String
let quantity: Int
let location: String
}
And I have instance an Entity to map MyStuff
:
@objc(Stuff)
public class Stuff: NSManagedObject {
}
extension Stuff {
@nonobjc public class func fetchRequest() -> NSFetchRequest<Stuff> {
return NSFetchRequest<Stuff>(entityName: "Stuff")
}
@NSManaged public var name: String?
@NSManaged public var quantity: Int64
@NSManaged public var location: String?
}
My question is, when I have the response of type MyStuff there is a way to loop thru the keys and map the values to core data?
for example:
let myStuff = MyStuff(name: "table", quantity: 1, location: "kitchen")
let myStuff = MyStuff(name: "table", quantity: 1, location: "kitchen")
for chidren in Mirror(reflecting: myStuff).children {
print(chidren.label)
print(chidren.value)
/*
insert values to core data
*/
}
I'll really appreciate your help
A smart solution is to adopt Decodable
in Stuff
Write an extension of CodingUserInfoKey
and JSONDecoder
extension CodingUserInfoKey {
static let context = CodingUserInfoKey(rawValue: "context")!
}
extension JSONDecoder {
convenience init(context: NSManagedObjectContext) {
self.init()
self.userInfo[.context] = context
}
}
In Stuff
adopt Decodable
and implement init(from:)
, it must be implemented in the class, not in the extension
@objc(Stuff)
public class Stuff: NSManagedObject, Decodable {
private enum CodingKeys: String, CodingKey { case name, quantity, location }
public required convenience init(from decoder: Decoder) throws {
guard let context = decoder.userInfo[.context] as? NSManagedObjectContext else { fatalError("Error: context doesn't exist!") }
let entity = NSEntityDescription.entity(forEntityName: "Stuff", in: context)!
self.init(entity: entity, insertInto: context)
let values = try decoder.container(keyedBy: CodingKeys.self)
name = try values.decodeIfPresent(String.self, forKey: .name)
quantity = try values.decodeIfPresent(Int64.self, forKey: .quantity) ?? 0
location = try values.decodeIfPresent(String.self, forKey: .location)
}
}
To decode the JSON you have to initialize the decoder with the convenience initializer
let decoder = JSONDecoder(context: context)
where context
is the current NSManagedObjectContext
instance.
Now you can create Stuff
instances directly from the JSON.