CoreData object to JSON in Swift 3

Question

I\'m struggling to get my CoreData objects into JSON so that I can use it to send to a web server.

This is how I currently fetch my objects from CoreData:

Answer 1

If you want you can get the results in dictionary format from core data using below :

let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName:"Record")
fetchRequest.resultType = .dictionaryResultType
do {
    records = try context.fetch(fetchRequest)
} catch {
    print("Error fetching data from CoreData")
}

Answer 2

In Swift 4 you can take advantage of the Encodable protocol and add the functionality directly to your Core Data object.

Assuming your NSManagedObject subclass extension looks like

extension Record {

    @NSManaged public var date: Date
    @NSManaged public var name: String
    @NSManaged public var quantity: Int32
    @NSManaged public var synched: Bool
    @NSManaged public var uuid: String

   ...

Adopt Encodable

extension Record : Encodable {

and add

private enum CodingKeys: String, CodingKey { case date, name, quantity, synched, uuid }

public func encode(to encoder: Encoder) throws {
    var container = encoder.container(keyedBy: CodingKeys.self)
    try container.encode(date, forKey: .date)
    try container.encode(name, forKey: .name)
    try container.encode(quantity, forKey: .quantity)
    try container.encode(synched, forKey: .synched)
    try container.encode(uuid, forKey: .uuid)
}

Then you can easily encode the records to JSON

do {
    records = try context.fetch(Record.fetchRequest())
    let jsonData = try JSONEncoder().encode(records)
} catch {
    print("Error fetching data from CoreData")
}

Answer 3

Here the code as an extension. Based on KavyaKavita's answer.

extension NSManagedObject {
  func toJSON() -> String? {
    let keys = Array(self.entity.attributesByName.keys)
    let dict = self.dictionaryWithValues(forKeys: keys)
    do {
        let jsonData = try JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted)
        let reqJSONStr = String(data: jsonData, encoding: .utf8)
        return reqJSONStr
    }
    catch{}
    return nil
  }
}

Usage:

let jsonString = YourCoreDataObject.toJSON()
print(jsonString)

Answer 4

You can convert your NSManageObject subclass object into dictionary by using following code

let record = recArray[index]
        let keys = Array(record.entity.attributesByName.keys)
        let dict = record.dictionaryWithValues(forKeys: keys)

After that you can use jsonserialization to convert that dictionary into json object

do{
        let jsonData = try JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted)
        let reqJSONStr = String(data: jsonData, encoding: .utf8)
        print(reqJSONStr!)
    }catch{

    }

Hope this will help.