Too many keypaths error - CoreData/SwiftUI/Xcode - swiftui

Question

I have been trying to start a project with Core Data so I can store data across multiple sessions of my app, but Xcode has been generating the error "currently unsupported (too many keypaths)" whenever I try to run a simulation of the app. I'm using Xcode and SwiftUI to build this.
I've looked online to see if I was implementing Core Data incorrectly, and followed several tutorials to create even a simple CoreData app. These do not fix the problem. I'm convinced it's something with my data model after I used Apple's blank Core Data template and added the entity (without changing the actual code). This still generated the error. The code that I used:
//
// EducationAppApp.swift
// EducationApp
//
// Created by <name> on 11/26/22.
//
import SwiftUI
import CoreData
#main
struct EducationAppApp: App {
#StateObject private var dataController = DataController()
var body: some Scene {
WindowGroup {
ContentView()
.environment(\.managedObjectContext, dataController.container.viewContext)
}
}
}
The ContentView file (it's only displaying "Hello World" after trying to fetch the data):
//
// ContentView.swift
// EducationApp
//
// Created by <name> on 11/26/22.
//
import SwiftUI
import CoreData
struct ContentView: View {
#Environment(\.managedObjectContext) var managedObjContext
#FetchRequest(sortDescriptors: []) var skills: FetchedResults<Skill>
var body: some View {
VStack {
Image(systemName: "globe")
.imageScale(.large)
.foregroundColor(.accentColor)
Text("Hello, world!")
}
.padding()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Here is my DataController object (created with help from this tutorial):
//
// DataController.swift
// EducationApp
//
// Created by <name> on 11/26/22.
//
import Foundation
import CoreData
class DataController: ObservableObject {
// Responsible for preparing a model
let container = NSPersistentContainer(name: "SkillModel")
init() {
container.loadPersistentStores { description, error in
if let error = error {
print("Failed to load data in DataController \(error.localizedDescription)")
}
}
}
func save(context: NSManagedObjectContext) {
do {
try context.save()
print("Data saved successfully. WUHU!!!")
} catch {
// Handle errors in our database
let nsError = error as NSError
fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
}
}
}
I do believe the problem is in the data model, which looks like this:
What the SkillModel screen looks like
If anybody could provide me with a reason why this might be occurring, I would greatly appreciate it!
*Note: the error doesn't seem to be occurring in any specific point in the app, just where it says "#main".
Full error text:
2022-11-26 17:08:19.888256-0600 EducationApp[35295:826163] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'currently unsupported (too many keypaths)'
*** First throw call stack:
(
0 CoreFoundation 0x00007ff800427378 __exceptionPreprocess + 242
1 libobjc.A.dylib 0x00007ff80004dbaf objc_exception_throw + 48
2 CoreData 0x00007ff8048c41ee +[NSSQLDerivedAttributeSQLGenerator generateSQLForDerivedAttribute:keypaths:] + 490
3 CoreData 0x00007ff804ae0526 __61-[NSSQLEntity_DerivedAttributesExtension _generateTriggerSQL]_block_invoke + 55
4 CoreFoundation 0x00007ff800371d12 __NSDICTIONARY_IS_CALLING_OUT_TO_A_BLOCK__ + 7
5 CoreFoundation 0x00007ff800372279 ____NSDictionaryEnumerate_block_invoke.11 + 50
6 CoreFoundation 0x00007ff80045dc4b CFBasicHashApply + 143
7 CoreFoundation 0x00007ff800371e32 __NSDictionaryEnumerate + 183
8 CoreData 0x00007ff804ae0429 -[NSSQLEntity_DerivedAttributesExtension _generateTriggerSQL] + 295
9 CoreData 0x00007ff804a2734b -[NSSQLiteConnection createTriggersForEntities:] + 305
10 CoreData 0x00007ff804a279d7 -[NSSQLiteConnection createTablesForEntities:] + 841
11 CoreData 0x00007ff804a20dc3 -[NSSQLiteConnection connect] + 3924
12 CoreData 0x00007ff8049e5ced __32-[NSSQLCore _loadAndSetMetadata]_block_invoke + 103
13 CoreData 0x00007ff804a24477 __37-[NSSQLiteConnection performAndWait:]_block_invoke + 28
14 libdispatch.dylib 0x000000010c268f5b _dispatch_client_callout + 8
15 libdispatch.dylib 0x000000010c27ad72 _dispatch_lane_barrier_sync_invoke_and_complete + 132
16 CoreData 0x00007ff804a23e7f -[NSSQLiteConnection performAndWait:] + 143
17 CoreData 0x00007ff8049e612d -[NSSQLCore loadMetadata:] + 270
18 CoreData 0x00007ff80499e1e7 __91-[NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:]_block_invoke + 3311
19 CoreData 0x00007ff8049b1bdd gutsOfBlockToNSPersistentStoreCoordinatorPerform + 182
20 libdispatch.dylib 0x000000010c268f5b _dispatch_client_callout + 8
21 libdispatch.dylib 0x000000010c27ad72 _dispatch_lane_barrier_sync_invoke_and_complete + 132
22 CoreData 0x00007ff804999ae1 _perform + 174
23 CoreData 0x00007ff80499d0a8 -[NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:] + 418
24 CoreData 0x00007ff80499c660 -[NSPersistentStoreCoordinator _doAddPersistentStoreWithDescription:privateCopy:completeOnMainThread:withHandler:] + 523
25 CoreData 0x00007ff80499ce92 -[NSPersistentStoreCoordinator addPersistentStoreWithDescription:completionHandler:] + 227
26 CoreData 0x00007ff804ae26d0 -[NSPersistentContainer _loadStoreDescriptions:withCompletionHandler:] + 272
27 CoreData 0x00007ff804ae2599 -[NSPersistentContainer loadPersistentStoresWithCompletionHandler:] + 398
28 EducationApp 0x000000010bd0bd42 $s12EducationApp14DataControllerCACycfc + 194
29 EducationApp 0x000000010bd0bc71 $s12EducationApp14DataControllerCACycfC + 33
30 EducationApp 0x000000010bd0c9e8 $s12EducationApp0abB0V15_dataController33_6EFB69B0CC1C2615428985B99CE4CBCALL7SwiftUI11StateObjectVyAA04DataD0CGvpfiAJycfu_AJycfu0_ + 24
31 SwiftUI 0x000000011065dea7 __swift_memcpy25_8 + 107639
32 SwiftUI 0x0000000110ebfa15 _swift_stdlib_malloc_size + 24560
33 SwiftUI 0x0000000110ebef63 _swift_stdlib_malloc_size + 21822
34 SwiftUI 0x0000000110a3290e block_destroy_helper + 16524
35 SwiftUI 0x00000001100df478 __swift_memcpy1_1 + 58428
36 AttributeGraph 0x00007ff81f5a21d7 _ZN2AG5Graph11UpdateStack6updateEv + 537
37 AttributeGraph 0x00007ff81f5a29ab _ZN2AG5Graph16update_attributeENS_4data3ptrINS_4NodeEEEj + 443
38 AttributeGraph 0x00007ff81f5aa4f5 _ZN2AG5Graph20input_value_ref_slowENS_4data3ptrINS_4NodeEEENS_11AttributeIDEjPK15AGSwiftMetadataRhl + 395
39 AttributeGraph 0x00007ff81f5c19f1 AGGraphGetValue + 218
40 SwiftUI 0x0000000110a32459 block_destroy_helper + 15319
41 SwiftUI 0x0000000110a3251d block_destroy_helper + 15515
42 SwiftUI 0x00000001100df478 __swift_memcpy1_1 + 58428
43 AttributeGraph 0x00007ff81f5a21d7 _ZN2AG5Graph11UpdateStack6updateEv + 537
44 AttributeGraph 0x00007ff81f5a29ab _ZN2AG5Graph16update_attributeENS_4data3ptrINS_4NodeEEEj + 443
45 AttributeGraph 0x00007ff81f5aa4f5 _ZN2AG5Graph20input_value_ref_slowENS_4data3ptrINS_4NodeEEENS_11AttributeIDEjPK15AGSwiftMetadataRhl + 395
46 AttributeGraph 0x00007ff81f5c19f1 AGGraphGetValue + 218
47 SwiftUI 0x0000000110a54093 get_witness_table 7SwiftUI4ViewRzlAA15ModifiedContentVyxAA25ComplicationIdiomModifierVGAaBHPxAaBHD1__AfA0cH0HPyHCHCTm + 65867
48 SwiftUI 0x0000000110a54147 get_witness_table 7SwiftUI4ViewRzlAA15ModifiedContentVyxAA25ComplicationIdiomModifierVGAaBHPxAaBHD1__AfA0cH0HPyHCHCTm + 66047
49 SwiftUI 0x000000011007ebcc objectdestroy.3084Tm + 22953
50 AttributeGraph 0x00007ff81f5a21d7 _ZN2AG5Graph11UpdateStack6updateEv + 537
51 AttributeGraph 0x00007ff81f5a29ab _ZN2AG5Graph16update_attributeENS_4data3ptrINS_4NodeEEEj + 443
52 AttributeGraph 0x00007ff81f5a9dbf _ZN2AG5Graph9value_refENS_11AttributeIDEPK15AGSwiftMetadataRh + 123
53 AttributeGraph 0x00007ff81f5c1a36 AGGraphGetValue + 287
54 SwiftUI 0x000000011016efe4 get_witness_table 7SwiftUI18DynamicViewContentRzlAA08ModifiedE0VyxAA21_TraitWritingModifierVyAA08OnDeleteG3KeyVGGAaBHPxAaBHD1__AiA0dI0HPyHCHCTm + 21338
55 SwiftUI 0x000000011106d2c5 block_destroy_helper.188 + 46430
56 SwiftUI 0x0000000111068845 block_destroy_helper.188 + 27358
57 SwiftUI 0x00000001110693e0 block_destroy_helper.188 + 30329
58 UIKitCore 0x000000010c56e70e +[UIScene _sceneForFBSScene:create:withSession:connectionOptions:] + 1394
59 UIKitCore 0x000000010d33fdb8 -[UIApplication _connectUISceneFromFBSScene:transitionContext:] + 1318
60 UIKitCore 0x000000010d340390 -[UIApplication workspace:didCreateScene:withTransitionContext:completion:] + 562
61 UIKitCore 0x000000010ccf17e0 -[UIApplicationSceneClientAgent scene:didInitializeWithEvent:completion:] + 350
62 FrontBoardServices 0x00007ff805445c8a -[FBSScene _callOutQueue_agent_didCreateWithTransitionContext:completion:] + 415
63 FrontBoardServices 0x00007ff805473deb __92-[FBSWorkspaceScenesClient createSceneWithIdentity:parameters:transitionContext:completion:]_block_invoke.187 + 102
64 FrontBoardServices 0x00007ff805453cda -[FBSWorkspace _calloutQueue_executeCalloutFromSource:withBlock:] + 209
65 FrontBoardServices 0x00007ff8054739e0 __92-[FBSWorkspaceScenesClient createSceneWithIdentity:parameters:transitionContext:completion:]_block_invoke + 344
66 libdispatch.dylib 0x000000010c268f5b _dispatch_client_callout + 8
67 libdispatch.dylib 0x000000010c26c8d2 _dispatch_block_invoke_direct + 496
68 FrontBoardServices 0x00007ff80549a6c0 __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 30
69 FrontBoardServices 0x00007ff80549a5b6 -[FBSSerialQueue _targetQueue_performNextIfPossible] + 174
70 FrontBoardServices 0x00007ff80549a6e8 -[FBSSerialQueue _performNextFromRunLoopSource] + 19
71 CoreFoundation 0x00007ff800386ebd __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
72 CoreFoundation 0x00007ff800386dfc __CFRunLoopDoSource0 + 157
73 CoreFoundation 0x00007ff800386659 __CFRunLoopDoSources0 + 308
74 CoreFoundation 0x00007ff800380db3 __CFRunLoopRun + 927
75 CoreFoundation 0x00007ff800380637 CFRunLoopRunSpecific + 560
76 GraphicsServices 0x00007ff809c0f28a GSEventRunModal + 139
77 UIKitCore 0x000000010d33e425 -[UIApplication _run] + 994
78 UIKitCore 0x000000010d343301 UIApplicationMain + 123
79 SwiftUI 0x0000000110dbcfa3 __swift_memcpy53_8 + 95801
80 SwiftUI 0x0000000110dbce50 __swift_memcpy53_8 + 95462
81 SwiftUI 0x00000001104dcafc __swift_memcpy195_8 + 12192
82 EducationApp 0x000000010bd0d05e $s12EducationApp0abB0V5$mainyyFZ + 30
83 EducationApp 0x000000010bd0d1b9 main + 9
84 dyld 0x000000010bf5d2bf start_sim + 10
85 ??? 0x000000011435252e 0x0 + 4633994542
)
libc++abi: terminating with uncaught exception of type NSException
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'currently unsupported (too many keypaths)'
terminating with uncaught exception of type NSException
CoreSimulator 857.7 - Device: iPhone 14 Pro (8DEDA7D0-7C9E-4AA0-9543-1745DE6286A8) - Runtime: iOS 16.0 (20A360) - DeviceType: iPhone 14 Pro
(lldb)

Answer 1

Resolved:
I went back and tried to determine if too many attributes was causing the problem. I deleted most of them and the code started working again, so I started adding them back in again. Now the code appears to be working correctly.