I have a List<Workout> object that occasionally needs to be sorted (e.g., if a user adds a Workout out of order), but I can't seem to get the new sorted List<Workout> to persist. My code works the moment it runs (i.e., it shows up on the view as sorted), but when I exit the ViewController or restart the app, I see nothing. The nothing is due to the exercise.workoutDiary.removeAll() persisting, but apparently the subsequent assignment to the exercise.workoutDiary = sortedWorkoutDiary is not persisting. Any ideas why?
Everything else works just fine. The typical recordWorkout() case works assuming nothing is entered out of order. So the persisting is working in nearly all cases except for this overwrite of the sorted List.
The update happens here:
struct ExerciseDetailViewModel {
private let exercise: Exercise!
func recordWorkout(newWorkout: Workout) {
let lastWorkout = exercise.workoutDiary.last // grab the last workout for later comparison
let realm = try! Realm()
try! realm.write {
exercise.workoutDiary.append(newWorkout) // write the workout no matter what
}
if let secondToLastWorkout = lastWorkout { // only bother checking out of order if there is a last workout...
if newWorkout.date < secondToLastWorkout.date { // ...and now look to see if they are out of order
let sortedWorkoutDiary = exercise.sortedWorkouts
try! realm.write {
exercise.workoutDiary.removeAll()
exercise.workoutDiary = sortedWorkoutDiary
}
}
}
}
}
final class Exercise: Object {
var workoutDiary = List<Workout>()
var sortedWorkouts: List<Workout> {
return List(workoutDiary.sorted("date"))
}
}
final class Workout: Object {
dynamic var date = NSDate()
var sets = List<WorkSet>()
}
List<T> properties in Realm Swift must be mutated in place, not assigned to. The Swift runtime does not provide any way for Realm to intercept assignments to properties of generic types. Instead, you should use methods like appendContentsOf(_:) to mutate the List<T>:
exercise.workoutDiary.removeAll()
exercise.workoutDiary.appendContentsOf(sortedWorkoutDiary)
This limitation on assignment to properties of generic types is why the Realm Swift documentation recommends that you declare such properties using let rather than var. This will allow the Swift compiler to catch these sorts of mistakes.
One further note: for your sortedWorkouts computed property, it'd be preferable for it to return Results<Workout> instead to avoid allocating and populating an intermediate List<Workout>.
Related
In the beginning of the project, Realm is great and easy to work and the project is getting complicated so I need to figure out how to decouple the realm layer and uiviewcontroller.
There is some awkwardness by writing a realm object with parameters. I would like to have object updated with the parameter then pass to the realm database to update object in (table?). Initially, I have a function to write a realm object by -
func createOrUpdateNote(note : Note, body : String, textSize : Float, toggleColor : Int) {
let realm = try! Realm()
do {
try realm.write {
if note.id == -1 {
note.id = NoteManager.createNotePrimaryId()
}
note.body = body
note.textSize = textSize
note.toggleColor = toggleColor
realm.add(note, update: true)
}
}
catch {
print(error.localizedDescription)
}
}
I would like to have like this function. Hope it clears up my question here.
func createOrUpdateNote(note : Note) {
let realm = try! Realm()
do {
try realm.write {
realm.add(note, update: true)
}
}
catch {
print(error.localizedDescription)
}
}
Now I have another viewcontroller to update the object with their preference of using language below.
func createOrUpdateNote(note : Note, language : String) {
let realm = try! Realm()
do {
try realm.write {
if note.id == -1 {
note.id = NoteManager.createNotePrimaryId()
}
note.language = language
realm.add(note, update: true)
}
}
catch {
print(error.localizedDescription)
}
}
There will be two similar functions (dup functions) in database layer and that will not work well when the project is getting more features so I'm stepping back to see if I can redesign the create or update the object approach.
I googled and there are several solutions like making UI object and copy the ui values over to the realm objects each time I do CRUD, create object with internal realm object (1 to 1 mapping), or I'm thinking about partial update but not sure how can I approach this situation. Ideally, I would prefer only object to carry over to be updated. Any suggestions?
If you have an existing (managed) Realm object, its properties can only be modified within a write block. However, ANY of it's properties can be modified and you really only need one block 'style' to do it.
So for example, if we have a Note Realm object
Note: Object {
#objc dynamic var body = ""
#objc dynamic var textSize = 12
#objc dynamic var language = "English"
}
any time we have access to that Note, we can modify it's properties within a write closure. Let's say a user is editing an existing note and changes the body, then clicks Save.
let realm = try Realm()
try! realm.write {
myNote.body = updatedBodyText
realm.add(myNote, update: true)
}
or they change the text size
let realm = try Realm()
try! realm.write {
myNote.textSize = updatedTextSize
realm.add(myNote, update: true)
}
Notice that those blocks are identical, other than which property is updated. The key is to hang on to a reference to the note when loaded, so you can then modify it's properties in a write block when saving.
There's no problem having multiple write blocks depending on what property you're saving. It really depends on your use case but that's common practice.
Generically speaking it could also be rolled into one function, something like this:
func saveMyNote(myNote: NoteClass, updatedData: String, fieldType: NoteFieldTypes) {
try! realm.write {
switch fieldType:
case .body:
myNote.body = updatedData
case .language:
myNote.language = updatedData
etc etc
realm.add(myNote, update: true)
}
You could also extend the class or a variety of other solutions. In general the write code is so small I would just use it wherever you need to update an objects fields.
I've got a relationship where:
A Parent has many Children
ie:
class Factory: Object {
public let engines = List<Engine>()
}
class Engine:Object {
private let parents:LinkingObjects<Factory> = LinkingObjects(fromType: Factory.self, property: "engines")
var parent:Factory? {
return self.parents.first
}
}
I read the factories via JSON and create the children (Engine) manually in a for-loop, similar to this:
var engines:[Engine] = [Engine]()
for _ in stride(from:0, to: 3, by: 1) {
let engine: Engine = Engine.init()
engines.append(engine)
}
return engines
In my test I want to query the parent of a given engine to ensure that the parent is correct; or perhaps get a parent attribute.
However, whenever I try to grab an attribute via the parent its always empty;
for (_, element) in (factories.enumerated()) {
for (_, eng) in element.engines.enumerated() {
print (eng.parent ?? "N/A" as Any) // Always prints out N/A
}
}
Ideally I want to be able to access the parent's data; like the name of the parent, perhaps costs, etc.
I've tried resetting simulator and also deleting derived data; but regardless of what I do the results are always N/A or empty.
How can I query the given element and ensure that I can grab the parent data?
Many thanks
Turns out there were a number of issues that I had to do to resolve this.
I was using XCTest and Realm was causing issues where there were multiple targets.
Make all my model classes' public
Remove the models from the test target, this included a file where the JSON data was being loaded into memory
I had to write my data into Realm, which I had not done;
let realm = try! Realm()
try! realm.write {
for parent:EYLocomotive in objects {
for _ in stride(from:0, to: parent.qty, by: 1) {
let engine : EYEngine = EYEngine.init()
parent.engines.append(engine)
}
realm.add(parent)
}
}
I have a method that should return Results, either by successfully querying, or by creating the records if they don't exist.
Something like:
class MyObject: Object {
dynamic var token = ""
static let realm = try! Realm()
class func findOrCreate(token token: String) -> Results<MyObject> {
// either it's found ...
let tokenResults = realm.objects(MyObject.self).filter("token = '\(token)'")
if !tokenResults.isEmpty {
return tokenResults
}
// ... or it's created
let newObject = MyObject()
newObject.token = token
try! realm.write {
realm.add(newObject)
}
// However, the next line results in the following error:
// 'Results<_>' cannot be constructed because it has no accessible initializers
return Results(newObject)
}
}
Maybe I should just be returning [MyObject] from this method. Is there any benefit to trying to keep it as Results instead of Array? I guess I'd lose any benefit of postponed evaluation since I'm already using isEmpty within the method, correct?
Results is an auto-updating view into underlying data in a Realm, which is why you can't construct it directly. So instead of return Results(newObject), you should return tokenResults, which will contain your newly added object, again because Results is an auto-updating view.
I'm using Realm, the project is on version 1.0.0.
When I create a list of Realm Objects (with data obtained from a web API), then try to save them to the Realm using this utility function in a struct:
static func saveRealmObjects(objects: [Object]) {
defer {
// Never entered
}
for object in objects {
let realm = try! Realm()
do {
try realm.write {
print("TEST: 1: object: \(object)")
realm.add(object)
print("TEST: 2")
}
} catch {
// Never entered
}
}
}
(Please don't judge me on the exact structure, I've been toying around seeing if anything will work).
I can tell from liberal use of print statements (mostly removed above) that the function gets to TEST: 1 okay, but fails to make it to TEST: 2, for the very first Object in the list I pass to the function.
I should note this function does work the first time I use it with the data (say after wiping the simulator and launching the app afresh), but then if I recreate the Objects and try to save them again it gets stuck.
I assumed Realm would use the private key on the Objects and overwrite any if necessary. But it seems to just get stuck.
-
Then - after it's stuck - if I try and get another set of results from Realm (using a different Realm object) I get the following error:
libc++abi.dylib: terminating with uncaught exception of type realm::InvalidTransactionException: Cannot create asynchronous query while in a write transaction
FYI I'm creating a different Realm object using try! Realm()
-
For reference, here is the Object I'm trying to save:
import Foundation
import RealmSwift
class MyObject: Object {
// MARK: Realm Primary Key
dynamic var id: String = ""
override static func primaryKey() -> String? {
return "id"
}
// MARK: Stored Properties
dynamic var date: NSDate? = nil
dynamic var numA = 0
dynamic var numB = 0
dynamic var numC = 0
dynamic var numD = 0
dynamic var numE = 0
dynamic var numF = 0
dynamic var numG = 0
dynamic var numH = 0
// MARK: Computed Properties
var computedNumI: Int {
return numD + numE
}
var computedNumJ: Int {
return numF + numG
}
}
(The variable names have been changed.)
-
Hopefully I'm doing something obviously wrong - this is my first time using Realm after all.
If you have any ideas why it's sticking (perhaps it's a threading issue?), or want more info, please answer or comment. Thank you.
Being the clever clogs I am, I've literally just found the answer by reading the documentation:
https://realm.io/docs/swift/latest/#creating-and-updating-objects-with-primary-keys
The add to Realm line needed to look like this:
realm.add(object, update: true)
Where the update flag will update Objects already saved with that primary key.
-
Although it would have been nice if it either gave some sort of obvious warning or crash upon trying to add the same object, or didn't cause other queries and writes to Realm to crash.
Full code on github
I am trying to rewrite my app to reduce mutability and take advantage of functional programming. I am having trouble figuring out where to start, since it seems like my architecture is to use modification in place almost everywhere. I could use some advice on a simple starting point of how to break this down into smaller pieces where I am maintaining immutability at each modification. Should I change my data storage architecture so that I am only storing/modifying/deleting the leaf objects?
Right now, from the root ViewController, I load my one monster object ExerciseProgram (which contains a RealmList of Exercise objects, which contains a RealmList of Workouts, which contains a RealmList of Sets....)
final class ExerciseProgram: Object {
dynamic var name: String = ""
dynamic var startDate = NSDate()
dynamic var userProfile: User?
var program = List<Exercise>()
var count: Int {
return program.count
}
}
Loaded here one time in MasterTableViewController.swift:
func load() -> ExerciseProgram? {
let realm = try! Realm()
return realm.objects(ExerciseProgram).first
}
and then modify the single ExerciseProgram object in place throughout the app, such as when recording a new workout.
To create a new Workout, I instantiate a new Workout object in RecordWorkoutTableViewController.swift:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if doneButton === sender {
if let date = newDate, weight = newWeight, setOne = newSetOne, setTwo = newSetTwo {
let newSets = List<WorkSet>()
newSets.append(WorkSet(weight: weight, repCount: setOne))
newSets.append(WorkSet(weight: weight, repCount: setTwo))
newWorkout = Workout(date: date, sets: newSets)
}
}
}
Which unwinds to ExerciseDetailTableViewController.swift where the storage occurs into the same monster ExerciseProgram object retrieved at the beginning:
#IBAction func unwindToExerciseDetail(sender: UIStoryboardSegue) {
if let sourceViewController = sender.sourceViewController as? RecordWorkoutTableViewController, newWorkout = sourceViewController.newWorkout {
let realm = try! Realm()
try! realm.write {
exercise.recordWorkout(newWorkout)
}
}
}
This behavior is replicated all over my app. If I want to edit or delete an existing workout, it's exactly the same.
The Exercise class is just this:
final class Exercise: Object {
dynamic var name = ""
dynamic var notes: String?
var workoutDiary = List<Workout>()
dynamic var goal = 0
...
func recordWorkout(newWorkout: Workout) {
workoutDiary.append(newWorkout)
}
func replaceWorkout(originalWorkout: Workout, newWorkout: Workout) {
workoutDiary[workoutDiary.indexOf(originalWorkout)!] = newWorkout
}
}
From what I can tell, looking at that schema, no, you shouldn't change it. If it's representing the types of information and their relations properly and it's already working in your app, then there's no need to change it.
If you feel it is overly complex or confusing, then it may be necessary to go back and look at your data model design itself before actually doing more work on the code itself. Review each relationship and each property in the linked objects, and make sure that it's absolutely critical that the data is saved at that level. In any case, Realm itself is very good at handling relationships between objects, so it's not 'wrong' to have several layers of nested objects.
Either way, Realm itself lends itself pretty well to functional programming since every property is explicitly immutable out of the box. Functional programming doesn't mean everything has to be immutable always though. Inevitably, you'll have to reach a point where you'll need to save changes to Realm; the mindset behind it is that you're not transforming data as you're working on it, and you minimise the number of points that actually do so.