Swift3 - Insert Relation In Core Data - core-data

Question

I have two Entities, namely
Clinic
Department
The relationship between them is many-to-many. i.e a clinic has many departments and a department has many clinics associated.
I have setup the entities in coredata.xcdatamodeld and generated the NSManagedObject classes. PFA the graph
I have the following code which takes care of inserting departments and clinics
import Foundation
import CoreData
import SwiftyJSON
import Kingfisher
class InstallManager {
let moc = NetworkManager.managedObjectContext
let data: JSON!
init(withData data: JSON) {
self.data = data
}
// Install Department
private func installDepartment() {
for(_,jsonData):(String, JSON) in self.data["deparment"]["list"] {
let department = NSEntityDescription.insertNewObject(forEntityName: "Department", into: moc)
department.setValue(jsonData["id"].int32, forKey: "id")
department.setValue(jsonData["name"].string, forKey: "name")
department.setValue(jsonData["icon"].string, forKey: "icon")
department.setValue(jsonData["slug"].string, forKey: "slug")
department.setValue(jsonData["revision"].int32, forKey: "revision")
do {
try moc.save()
} catch {
fatalError("\(error)")
}
}
}
// Install Clinic
private func installClinic() {
let departmentList = fetchDepartmentList()
for (_,jsonData):(String, JSON) in self.data["clinic"]["list"] {
let coverPictureAbsolute = "\(jsonData["cover_picture"].string!)"
let coverPictureRelative = (coverPictureAbsolute as NSString).lastPathComponent
let clinic = NSEntityDescription.insertNewObject(forEntityName: "Clinic", into: moc)
clinic.setValue(jsonData["id"].int32, forKey: "id")
clinic.setValue(jsonData["name"].string, forKey: "name")
clinic.setValue(jsonData["slogan"].string, forKey: "slogan")
clinic.setValue(jsonData["profile"].string, forKey: "profile")
clinic.setValue(jsonData["address"].string, forKey: "address")
clinic.setValue(jsonData["telephone"].string, forKey: "telephone")
clinic.setValue(jsonData["email"].string, forKey: "email")
clinic.setValue(jsonData["website"].string, forKey: "website")
clinic.setValue(coverPictureRelative, forKey: "cover_picture")
clinic.setValue(jsonData["latitude"].string, forKey: "latitude")
clinic.setValue(jsonData["longitude"].string, forKey: "longitude")
clinic.setValue(jsonData["slug"].string, forKey: "slug")
clinic.setValue(jsonData["revision"].int32, forKey: "revision")
let clinicEntity = clinic.value(forKeyPath: "departments") as! Clinic
for department in departmentList {
clinicEntity.addToDepartments(department)
print(department.name!)
}
do {
try moc.save()
} catch {
fatalError("\(error)")
}
}
}
private func fetchDepartmentList() -> [Department] {
var departmentList:[Department]!
let request: NSFetchRequest<Department> = Department.fetchRequest()
do {
departmentList = try moc.fetch(request)
} catch {
fatalError("Cannot fetch clinics list \(error)")
}
return departmentList
}
public func install() {
self.installDepartment()
self.installClinic()
}
}
My problem is while inserting relations between clinic and departments, I have the list of department ids which I want to set relation with the clinic. As you can see in the above code, I tried the following code
let departmentList = fetchDepartmentList()
let clinicEntity = clinic.value(forKeyPath: "departments") as! Clinic
for department in departmentList {
clinicEntity.addToDepartments(department)
print(department.name!)
}
But the line clinicEntity throws me the following error
Could not cast value of type '_NSFaultingMutableSet' to 'APP.Clinic'
What is the issue here? How can I set the relation?
UPDATE:
Here is the auto-generated classes from core-data (NSManagedObject SubClass)
// filename: Clinic.swift
import Foundation
import CoreData
#objc(Clinic)
public class Clinic: NSManagedObject {
}
// filename: Clinic+CoreDataProperties
import Foundation
import CoreData
extension Clinic {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Clinic> {
return NSFetchRequest<Clinic>(entityName: "Clinic");
}
#NSManaged public var address: String?
#NSManaged public var cover_picture: String?
#NSManaged public var email: String?
#NSManaged public var id: Int32
#NSManaged public var latitude: NSDecimalNumber?
#NSManaged public var longitude: NSDecimalNumber?
#NSManaged public var name: String?
#NSManaged public var profile: String?
#NSManaged public var revision: Int32
#NSManaged public var slogan: String?
#NSManaged public var slug: String?
#NSManaged public var telephone: String?
#NSManaged public var website: String?
#NSManaged public var departments: NSSet?
}
// MARK: Generated accessors for departments
extension Clinic {
#objc(addDepartmentsObject:)
#NSManaged public func addToDepartments(_ value: Department)
#objc(removeDepartmentsObject:)
#NSManaged public func removeFromDepartments(_ value: Department)
#objc(addDepartments:)
#NSManaged public func addToDepartments(_ values: NSSet)
#objc(removeDepartments:)
#NSManaged public func removeFromDepartments(_ values: NSSet)
}

Answer 1

For a to-many relationship you need to get the mutableSetValueForKey because the type is NSSet rather than Clinic.
let clinicEntity = clinic.mutableSetValue(forKey: "departments")
for department in departmentList {
clinicEntity.add(department)
print(department.name!)
}
or simpler
let clinicEntity = clinic.mutableSetValue(forKey: "departments")
clinicEntity.addObjects(from: departmentList)
To use the autogenerated method you can replace
let clinicEntity = clinic.value(forKeyPath: "departments") as! Clinic
for department in departmentList {
clinicEntity.addToDepartments(department)
print(department.name!)
}
with
clinic.addToDepartments(NSSet(array: departmentList))
PS: I'd recommend to use the more convenient dot notation, for example
department.id = jsonData["id"].int32
department.name = jsonData["name"].string
department.icon = jsonData["icon"].string
department.slug = jsonData["slug"].string
department.revision = jsonData["revision"].int32