I try to save some objects to a Realm, but even after setting the member variables and saving it - after reading the Realm, the objects have their default values.
class Person: Object {
#objc dynamic var Name: String = "test"
#objc dynamic var Age: Int = 0;
}
do {
let realm = try Realm();
var p = Person();
p.Name = "Poirot"
p.Age = 55
try realm.write {
realm.add(p)
print("Person:",p.Name); // <-- Here its correct: "Poirot"
}
} catch let error {
print(error.localizedDescription)
}
do {
let realm = try Realm()
let data = realm.objects(Person.self)
for persons in data {
print("Person:", persons.Name); // <-- Here its wrong: "test"
}
} catch let error {
print(error.localizedDescription)
}
After running this, it would print:
Person: Poirot
Person: test
Can someone explain me this behavior and tell me what I´m doing wrong?
Thank you!
If you run your code in foreground it is fine.
If you are on a background thread (a thread without a RunLoop) than you need to refresh your realm.
let realm = try Realm()
realm.refresh()
let data = realm.objects(Person.self)
for persons in data {
print("Person:", persons.Name); // <-- Here its wrong: "test"
}
Have a look at the Realm threading documentation and scroll down to Refreshing Realms
Related
I'm trying to load data into a CoreData entity "Articles" from a function I would like to call in an init() {} call when my app starts which means I'm not doing this from within a view.
I get the message "Accessing Environment's value outside of being installed on a View. This will always read the default value and will not update."
and would like to work around that. I'm using Xcode 14.2
I do have a standard PersistenceController setup and so on
Here is where I run into the issue "let section = SectionsDB(context: managedObjectContext)"
#main
struct ArticlesExampleApp: App {
let persistanceController = PersistanceController.shared
init() {
let x = Articles.loadSections()
}
var body: some Scene {
WindowGroup {
MasterView()
.environment(\.managedObjectContext, persistanceController.container.viewContext)
}
}
class Articles {
class func loadSections() -> Int {
#Environment(\.managedObjectContext) var managedObjectContext
// Initialize some variables
let myPath = Bundle.main.path(forResource: "Articles", ofType: "json")
// Initialize some counters
var sectionsCount = 0
do {
let myData = try Data(contentsOf: URL(fileURLWithPath: myPath!), options: .alwaysMapped)
// Decode the json
let decoded = try JSONDecoder().decode(ArticlesJSON.self, from: myData)
// **here is where I run into the error on this statement**
let section = SectionsDB(context: managedObjectContext)
while sectionsCount < decoded.sections.count {
print("\(decoded.sections[sectionsCount].section_name) : \(decoded.sections[sectionsCount].section_desc)")
section.name = decoded.sections[sectionsCount].section_name
section.desc = decoded.sections[sectionsCount].section_desc
sectionsCount+=1
}
PersistanceController.shared.save()
} catch {
print("Error: \(error)")
}
return sectionsCount
}
}
Since you are already using a singleton, you can just use that singleton in your loadSections function:
let section = SectionsDB(context: PersistanceController.shared.container.viewContext)
And, remove the #Environment(\.managedObjectContext) var managedObjectContext line
I have been observing high CPU times in background threads while inserting the coredata objects, and from analyser i could find that it's coming majorly because of some relationships i was creating one by one, and those could be in thousands.
So i thought if i could create them with batch insert. I can do that easily for objects using without relationships using NSBatchInsertRequest, but with relationships, I can't seem to find any clean way.Without relationships, i can easily create dictionaries and insert using the above request.
With relationships, i also tried using the object handler method of NSBatchInsertRequest, but even that is giving me an exception
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Illegal attempt to establish a relationship 'run' between objects in different contexts
This is how i am trying to make sure that the trackpoint getting added is using the run object from the same context as the one in which its being created
func addTrackPoints(run: RunModel, objectId: NSManagedObjectID) async throws {
let locations:[CLLocation] = run.getLocations()
let count = run.getLocations().count
var index = 0
let batchInsert = NSBatchInsertRequest(entity: TrackPoint.entity()) { (managedObject: NSManagedObject) -> Bool in
guard index < count else { return true }
if let trackPoint = managedObject as? TrackPoint {
let data = locations[index]
guard let run = try? StorageService.shared.getBackgroundContext().object(with: objectId) as? Run else {
fatalError("failed to get run object")
}
trackPoint.run = run
}
index += 1
return false
}
try await StorageService.shared.batchInsert(entity: TrackPoint.entity(), batchInsertRequest: batchInsert, context: StorageService.shared.getBackgroundContext())
}
I also tried it without accessing the object from same context but instead tried directly using the Run object that i had created. It didn't crash, but it still didn't create the relationship.Also it forced me to remove the concurrencydebug run argument.
func addTrackPoints(run: RunModel, object: Run) async throws {
let locations = run.getLocations()
let count = run.getLocations().count
var index = 0
let batchInsert = NSBatchInsertRequest(entity: TrackPoint.entity()) { (managedObject: NSManagedObject) -> Bool in
guard index < count else { return true }
if let trackPoint = managedObject as? TrackPoint {
let data:CLLocation = locations[index]
trackPoint.run = object
}
index += 1
return false
}
try await StorageService.shared.batchInsert(entity: TrackPoint.entity(), batchInsertRequest: batchInsert, context: StorageService.shared.getBackgroundContext()) }
StorageService
public func batchInsert(entity: NSEntityDescription, batchInsertRequest: NSBatchInsertRequest, context: NSManagedObjectContext? = nil) async throws {
var taskContext:NSManagedObjectContext? = context
if(taskContext == nil) {
taskContext = StorageService.shared.newTaskContext()
// Add name and author to identify source of persistent history changes.
taskContext?.name = "importContext"
taskContext?.transactionAuthor = "import\(entity.name ?? "entity")"
}
/// - Tag: performAndWait
try await taskContext?.perform {
// Execute the batch insert.
do{
let fetchResult = try taskContext?.execute(batchInsertRequest)
if let batchInsertResult = fetchResult as? NSBatchInsertResult,
let success = batchInsertResult.result as? Bool, success {
return
}
} catch {
self.logger.error("Failed to execute batch insert request. \(error)")
}
throw SSError.batchInsertError
}
logger.info("Successfully inserted data for \(entity.name ?? "entity")")
}
Any help would be deeply appreciated :-)
How app works, I send request to server, get some results and want data to be saved in core data for further usage to send request to server only when needed. so next time I will query data from database.
Here is sample:
I always save data in background context, which is configured like this:
func getBgContext() -> NSManagedObjectContext {
let bgContext = self.persistenceController.container.newBackgroundContext()
bgContext.automaticallyMergesChangesFromParent = true
bgContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
return bgContext
}
Next I construct my data models like this so decoder will handle entity creation and data parsing + insertion in dbContext:
public class SomeDataModel: NSManagedObject, Codable {
var entityName: String = "SomeDataModel"
enum CodingKeys: String, CodingKey {
case id = "id"
case someData = "someData"
}
public required convenience init(from decoder: Decoder) throws {
guard
let context = decoder.userInfo[CodingUserInfoKey.managedObjectContext] as? NSManagedObjectContext,
let entity = NSEntityDescription.entity(forEntityName: "SomeDataModel", in: context)
else {
throw DecoderConfigurationError.missingManagedObjectContext
}
self.init(entity: entity, insertInto: context)
let values = try decoder.container(keyedBy: CodingKeys.self)
id = try values.decode(Int32.self, forKey: .id)
someData = try values.decodeIfPresent(String.self, forKey: .someData)
}
public func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(id, forKey: .id)
try container.encode(someData, forKey: .someData)
}
func toExternalModel() -> SomeExternalUsableModel {
return SomeExternalUsableModel(id: id, someData: someData)
}
}
extension SomeDataModel {
#nonobjc public class func fetchRequest() -> NSFetchRequest<SomeDataModel> {
return NSFetchRequest<SomeDataModel>(entityName: "SomeDataModel")
}
#NSManaged public var someData: String?
#NSManaged public var id: Int32
}
extension SomeDataModel: Identifiable {
}
to pass dbcontext to decoder I do next:
extension CodingUserInfoKey {
static let managedObjectContext = CodingUserInfoKey(rawValue: "managedObjectContext")!
}
dbContext - create background context somewhere in API helper class, and use this context for all the parsings below.
and next I do parsing with decoder when respond from server comes:
let model = try self.dbContext.performAndWait {
let jsonDecoder = JSONDecoder()
let jsonEncoder = JSONEncoder()
// pass context to decoder/encoder
jsonDecoder.userInfo[CodingUserInfoKey.managedObjectContext] = self.dbContext
jsonEncoder.userInfo[CodingUserInfoKey.managedObjectContext] = self.dbContext
// parse model, used generic for reuse for other models
let model = try jsonDecoder.decode(T.self, from: result.data)
// after this line - all the data is parsed from response from server, and saved to dbContext, and contained in model as well
if self.dbContext.hasChanges {
do {
try self.dbContext.save()
self.dbContext.refreshAllObjects() // refresh context objects to ELIMINATE all outdated db objects in memory (specially when you will have relations, they could remain in memory until updated)
} catch let error {
// process error
}
}
return model
}
// do with saved and ready to use data in models whatever needed:
return model
and extensions used for performAndWait
extension NSManagedObjectContext {
func performAndWait<T>(_ block: () throws -> T) throws -> T? {
var result: Result<T, Error>?
performAndWait {
result = Result { try block() }
}
return try result?.get()
}
func performAndWait<T>(_ block: () -> T) -> T? {
var result: T?
performAndWait {
result = block()
}
return result
}
}
So instead of using user defualts I want to persist some settings using Realm.
I've created a class for the settings
import Foundation
import RealmSwift
class NutritionSettings: Object {
#objc dynamic var calories: Int = 0
#objc dynamic var proteins: Int = 0
#objc dynamic var carbohydrates: Int = 0
#objc dynamic var fats: Int = 0
}
But in my view controller I don't know how to save just one instance of it
I've tried
let realm = try! Realm()
let settings = NutritionSettings()
do {
try realm.write{
settings.calories = cals!
settings.carbohydrates = carbs!
settings.fats = fats!
settings.proteins = proteins!
}
} catch {
print("error saving settings")
}
Since I know doing realm.add would just add another NutritionSettings object which is not what I want. I was unable to clarify anything using the documentation. Any help would be appreciated thanks.
I faced a similar issue in my project when I tried to save a user session object. If you want to save a unique object, override the primaryKey() class method and set the unique key for it.
#objcMembers class NutritionSettings: Object {
static let uniqueKey: String = "NutritionSettings"
dynamic var uniqueKey: String = NutritionSettings.uniqueKey
dynamic var calories: Int = 0
override class func primaryKey() -> String? {
return "uniqueKey"
}
}
Then to receive the object just use the unique key.
// Saving
let settings = NutritionSettings()
settings.calories = 100
do {
let realm = try Realm()
try realm.write {
realm.add(settings, update: .modified)
}
} catch {
// Error handling
}
// Reading
var settings: NutritionSettings?
do {
let realm = try Realm()
let key = NutritionSettings.uniqueKey
settings = realm.object(ofType: NutritionSettings.self, forPrimaryKey: key)
} catch {
// Error handling
}
if let settings = settings {
// Do stuff
}
Hope it will help somebody.
If you look at the example realm provides https://realm.io/docs/swift/latest you can see that in order to only save one object you still have to do an add. Once you have added the object to the database you can fetch that object and do a write that modifies the internal properties
let realm = try! Realm()
let settings = NutritionSettings()
settings.id = 1
do {
try realm.write{
realm.add(settings)
}
} catch {
print("error saving settings")
}
Next you can fetch and modify that single instance that you saved
let realm = try! Realm()
let settings = realm.objects(NutritionSettings.self).filter("id == 1").first
do {
try realm.write{
settings.calories = cals!
settings.carbohydrates = carbs!
settings.fats = fats!
settings.proteins = proteins!
}
} catch {
print("error saving settings")
}
class User: Object {
#objc dynamic var id = ""
#objc dynamic var dateFirstStart:TimeInterval = 0
//dates
#objc dynamic var dateLastStart:TimeInterval = 0
#objc dynamic var dateLastAppClose:TimeInterval = 0
#objc dynamic var dateLastDataUpdateCheck:TimeInterval = 0
#objc dynamic var dateLastFilesUpdateCheck:TimeInterval = 0
override class func primaryKey() -> String? {
return "id"
}
}
Do I really have to create a function for each value to change? Like this:
func updateUserDateFirstStart(date:Date){
do {
let realm = try Realm()
try realm.write {
let user = getUser()
user. dateLastStart = Date().timeIntervalSince1970
}
} catch let error as NSError {
print("ERROR \(error.localizedDescription)")
}
}
What I want is something like
let user = getUser()
user.dateLastStart = Date().timeIntervalSince1970
dataManager.updateUser(user)
And in my DataManager:
func updateUser(user:User){
do {
let realm = try Realm()
try realm.write {
realm.add(user, update: true)
}
} catch let error as NSError {
print("ERROR \(error.localizedDescription)")
}
}
But if I do it as you can see in my wishtohave solution I always get an Attempting to modify object outside of a write transaction error.
I tried to create a complete new Object and use the id from the object I want to change. This works but would need even more lines of code.
You can use KVO to update one value in realm object
how to call
let user = getUser()
self.update(ofType:user, value: Date().timeIntervalSince1970 as AnyObject, key: "dateLastStart")
Helper func
func update(ofType:Object,value:AnyObject,key:String)->Bool{
do {
let realm = try Realm()
try realm.write {
ofType.setValue(value, forKeyPath: key)
}
return true
}catch let error as NSError {
fatalError(error.localizedDescription)
}
return false
}
I have Realm Object that save list from the JSON Response. But now i need to remove the object if the object is not on the list again from JSON. How i do that?
This is my init for realm
func listItems (dic : Array<[String:AnyObject]>) -> Array<Items> {
let items : NSMutableArray = NSMutableArray()
let realm = try! Realm()
for itemDic in dic {
let item = Items.init(item: itemDic)
try! realm.write {
realm.add(item, update: true)
}
items.addObject(item)
}
return NSArray(items) as! Array<Items>
}
imagine your Items object has an id property, and you want to remove the old values not included in the new set, either you could delete everything with just
let result = realm.objects(Items.self)
realm.delete(result)
and then add all items again to the realm,
or you could also query every item not included in the new set
let items = [Items]() // fill in your items values
// then just grab the ids of the items with
let ids = items.map { $0.id }
// query all objects where the id in not included
let objectsToDelete = realm.objects(Items.self).filter("NOT id IN %#", ids)
// and then just remove the set with
realm.delete(objectsToDelete)
I will get crash error if I delete like top vote answer.
Terminating app due to uncaught exception 'RLMException', reason: 'Can only add, remove, or create objects in a Realm in a write transaction - call beginWriteTransaction on an RLMRealm instance first.'
Delete in a write transaction:
let items = realm.objects(Items.self)
try! realm!.write {
realm!.delete(items)
}
func realmDeleteAllClassObjects() {
do {
let realm = try Realm()
let objects = realm.objects(SomeClass.self)
try! realm.write {
realm.delete(objects)
}
} catch let error as NSError {
// handle error
print("error - \(error.localizedDescription)")
}
}
// if you want to delete one object
func realmDelete(code: String) {
do {
let realm = try Realm()
let object = realm.objects(SomeClass.self).filter("code = %#", code).first
try! realm.write {
if let obj = object {
realm.delete(obj)
}
}
} catch let error as NSError {
// handle error
print("error - \(error.localizedDescription)")
}
}
What you can do is assign a primary key to the object you are inserting, and when receiving a new parsed JSON you verify if that key already exists or not before adding it.
class Items: Object {
dynamic var id = 0
dynamic var name = ""
override class func primaryKey() -> String {
return "id"
}
}
When inserting new objects first query the Realm database to verify if it exists.
let repeatedItem = realm.objects(Items.self).filter("id = 'newId'")
if !repeatedItem {
// Insert it
}
The first suggestion that comes to mind is to delete all objects before inserting new objects from JSON.
Lear more about deleting objects in Realm at https://realm.io/docs/swift/latest/#deleting-objects
do {
let realm = try Realm()
if let obj = realm.objects(Items.self).filter("id = %#", newId).first {
//Delete must be perform in a write transaction
try! realm.write {
realm.delete(obj)
}
}
} catch let error {
print("error - \(error.localizedDescription)")
}
There is an easier option to remove 1 object:
$item.delete()
remember to have the Observable object like:
#ObservedRealmObject var item: Items
var realm = try! Realm()
open func DeleteUserInformation(){
realm.beginWrite()
let mUserList = try! realm.objects(User.self)
realm.delete(mUserList)
try! realm.commitWrite()
}