I have a Model Class Note:
@Model
class Note {
var id: UUID
var created: Date
var content: String
@Relationship(inverse: \Event.notes)
var events: [Event]?
init(_ content: String, created: Date = .now, events: [Event] = []) {
self.id = UUID()
self.created = created
self.content = content
self.events = events
}
}
And Event:
@Model
class Event: Hashable, Equatable {
var id: String
var name: String
var eventNotes: String?
@Relationship var notes: [Note]?
// @Transient does not publish (iOS bug?), use .ephemeral instead
@Attribute(.ephemeral) var isSelected: Bool = false
init(_ name: String = "Unnamed Event", calendarId: String, eventNotes: String) {
self.id = calendarId
self.name = name
self.eventNotes = eventNotes
}
init(from calendarEvent: EKEvent) {
self.id = calendarEvent.eventIdentifier
self.name = calendarEvent.title
self.eventNotes = calendarEvent.notes ?? ""
}
...
static func loadEvents(date: Date = Date()) -> [Event] {
...
}
}
I have the following View hierarchy
NoteInputView which has @State var events: [Event] = []
SelectEventButton which has @Binding var events: [Event] and calls Event.loadEvent() to retrieve list of events
SelectEventSheet which has @Binding var events: [Event] and lets the user toggle isSelected
GitHub Gist with all relevant files
Adding notes with same events crashes...
With this setup, I attempt so save new notes in NoteInputView by calling addNote:
func addNote() -> Note {
let selectedEvents = events.filter({ $0.isSelected })
let note = Note(newNoteContent, events: selectedEvents)
context.insert(note)
do {
try context.save()
} catch {
print(error)
}
return note
}
This works for the first note after opening the app, or if every subsequent note has a different event selected. However, storing a second note with the same event crashes with the following error:
"Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Illegal attempt to establish a relationship 'events' between objects in different contexts"
(complete error see here) The error occurs at context.insert, which doesn't throw.
If I force quit the app, and then add a note with the same events as an already persisted note, no error is thrown (until a I add another note with the same event without force-quitting).
... but not because one cannot refer to the same events twice
It's not a problem of referring to the same events, as the following code also works fine for multiple notes:
func addNote() -> Note {
// This works, despite notes also always referring to the same events
let note = Note(newNoteContent, events: Event.loadEvents())
context.insert(note)
do {
try context.save()
} catch {
print(error)
}
return note
}
.
... workaround? Manually adding events to the context before adding it to the notes
One workaround seems to be to add the events to the context before adding the note:
func addNote() -> Note {
let selectedEvents = events.filter({ $0.isSelected })
selectedEvents.forEach({context.insert($0)})
let note = Note(newNoteContent, events: events)
context.insert(note)
do {
try context.save()
} catch {
print(error)
}
return note
}
.
... but why?
While this works, I cannot quite make sense of this. It seems that passing events around between views may be the culprit, or that loadEvents is called in a child view.
Would love some advice, since this doesn't seem like intended behavior.