CODEWITHSUNDEEP
iosswiftcore-data
Aykhan Hagverdili
Aykhan Hagverdili

Reputation: 29985

CoreData with transformable attribute fails on save

I want to use CoreData and save a custom class attribute in one of the entities. The way to do that seems to be to use Transformable:

enter image description here

And then I try to add a single element and save it as:

import UIKit;
import CoreData;

public class EntityData: NSObject, NSSecureCoding
{
    public static var supportsSecureCoding: Bool { true }

    public func encode(with coder: NSCoder) {
        coder.encode(self.name, forKey: "name");
    }

    public required init?(coder: NSCoder) {
        self.name = coder.decodeObject(forKey: "name") as? String;
    }

    var name: String?;

    init(name: String?) {
        self.name = name;
    }
}

class ViewController: UIViewController {
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(_: animated);

        let context  = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext;
        
        let entity = Entity(context: context);
        
        entity.id = URL(string: "google.com");
        entity.data = EntityData(name: "Foo");
        
        do {
            try context.save();
        } catch {
            print("While saveing: \(error)");
        }
    }
}

This fails with:

2021-09-30 13:12:58.865312+0400 tmpCoreData[5815:170015] [error] error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x6000034f6040> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null)
CoreData: error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x6000034f6040> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null)
2021-09-30 13:12:58.865530+0400 tmpCoreData[5815:170015] [error] error: -executeRequest: encountered exception = <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo = (null)
CoreData: error: -executeRequest: encountered exception = <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo = (null)
2021-09-30 13:12:58.865983+0400 tmpCoreData[5815:170015] [error] error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x6000034e4300> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null)
CoreData: error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x6000034e4300> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null)
2021-09-30 13:12:58.866158+0400 tmpCoreData[5815:170015] [error] error: -executeRequest: encountered exception = <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo = (null)
CoreData: error: -executeRequest: encountered exception = <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo = (null)
2021-09-30 13:12:58.866558+0400 tmpCoreData[5815:170015] [error] error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x6000034ec0c0> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null)
CoreData: error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x6000034ec0c0> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null)
2021-09-30 13:12:58.900366+0400 tmpCoreData[5815:170015] [error] error: -executeRequest: encountered exception = <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo = (null)
CoreData: error: -executeRequest: encountered exception = <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo = (null)
2021-09-30 13:12:58.912131+0400 tmpCoreData[5815:170015] [error] error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x6000034f83c0> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null)
CoreData: error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x6000034f83c0> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null)
While saveing: Error Domain=NSCocoaErrorDomain Code=134060 "A Core Data error occurred."

I am not sure what I am doing wrong. This is all the code I have, there is nothing else going on that I've added.

Upvotes: 1

Views: 1142

Answers (1)

vadian
vadian

Reputation: 285260

A transformable attribute requires a class conforming to NS(Secure)Coding (not Codable!) and the implementation of archiving the object(s). Note the NSSecureUnarchiveFromData errors.

In the Swift world consider to declare the attribute as String, encode the object to JSON with Codable and add a computed property for the seamless conversion.

Upvotes: 2

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