How to use Codable and Coredata together?

Question

I am trying to implement Codable with Coredata. I've tried following the following answer, but still have had no luck.

How to use swift 4 Codable in Core Data?

The error/problem I am having is my project is continuing to say: "Argument type 'User' does not conform to expected type 'Encodable' whenever I try to encode or decode the object.

I have created the Entity in CoreData and made NSManagedObject subclasses:

import Foundation
import CoreData

@objc(User)
public class User: NSManagedObject, Codable {

// MARK: - Codable setUp
enum CodingKeys: String, CodingKey {
    case fullname
    case email
    case zipcode
    case usertype = "user_type"
}


// MARK: - Decoding the data
required convenience init(from decoder: Decoder) {
    guard let context = decoder.userInfo[.context] as? NSManagedObjectContext else {NSLog("Error: with User context!")
        return
    }

    guard let entity = NSEntityDescription.entity(forEntityName: "User", in: context) else {
        NSLog("Error with user enity!")
        return
    }

    self.init(entity: entity, in: context)

    let values = try decoder.container(keyedBy: CodingKeys.self)
    fullname = try values.decode(String.self, forkey: .fullname)
    email = try values.decode(String.self, forkey: .email)
    zipcode = try values.decode(String.self, forkey: .zipcode)
    userType = try values.decode(String.self, forkey: .userType)

}

// MARK: - Encoding the data
func encode(to encoder: Encoder) throws {
    var container = try encoder.container(keyedBy: CodingKeys.self)

    try container.encode(fullname, forkey: .fullname)
    try container.encode(email, forkey: .email)
    try container.encode(usertype, forkey: .usertype)
    try container.encode(zipcode, forkey: .zipcode)
}


}

// This helps with decoding
extension CodingUserInfoKey {
   static let context = CodingUserInfoKey(rawValue: "context")
}

When I try to decode the object and save the user to firebase I get a warning that says "In argument type 'User.Type', 'User' does not conform to expected type 'Decodable'

When I try to encode I get a warning that says "Argument type 'User' does not conform to expected type 'Encodable'

Your code gives different errors in a playground. It says your init and encode methods must be declared public because your User class is public. Are you not getting those errors? — Mike Taverne

vadian vadian · Accepted Answer · 2018-03-03T10:37:01

User' does not conform to expected type 'Decodable

occurs due to a typo (case sensitivity matters):

case usertype ... vs. ...forKey: .userType)

and the encode/decode(:forKey:) methods have a capital K

How to use Codable and Coredata together?

2 Answers