I'm trying #swift and #swiftdata for the first time, and need help with an error.
I get: SwiftData/BackingData.swift:201: Fatal error: expected attribute to be Codable
while inserting this model into a context
@Model
final class Item {
var name: String
var kind: Kind
enum Kind: String, Codable {
case function
case module
}
init(name: String, kind: Kind) { ... }
}
Removing kind from the model fixes it.
Is this even my bug? Or a SwiftData issue?
@AndrewMettier SwiftData and the error message are both new (Google still returns no results found for "Fatal error: expected attribute to be Codable"), ChatGPT is... unlikely... to have the right context to help since it's training data is all from before any of this existed.
On a basic attempt it returns something confident sounding, but that does not fix the issue... and doesn't really make sense if you stop to think about it: https://chat.openai.com/share/a48b19e9-122f-406e-8218-daada705594f
@sfko I admit to not reading the release notes, but I tried Int backed first, so it shouldn't just be the prior. The latter sounds pretty plausible.
The forums you're referring to are these ones? https://forums.swift.org/
@jonduenas Someone else mentioned this, but the exact same code with `Kind: String` replaced with `Kind: Int` results in the exact same error.
It's actually what I tried first.
Where in your files does the error appear? I’m not able to reproduce.
Are you using XCode beta 2?
Yes, I'm using XCode beta 2 (Version 15.0 beta 2 (15A5161b))
Note it's a runtime error not a compile time one.
The actual error prints in x-code after this line of code, when you click the button:
```
Button("+", action: {modelContext.insert(Item(name: "test", kind: Item.Kind.function))})
```
In the meantime I've learned two new things:
1/5
1) The contents of the init function matters, it's
```
init(name: String, kind: Kind) {
self.name = name
self.kind = kind
}
```
Commenting out `self.kind = kind` avoids the crash.
2) I'm starting this in a DocumentGroup, using a `WindowGroup{ ... }.modelContainer(for: Item.self)` avoids the crash
```
DocumentGroup(editing: Item.self, contentType: .rot) {
ContentView()
}
```
Source follows
2/5
```
import SwiftUI
import SwiftData
@main
struct MainApp: App {
var body: some Scene {
DocumentGroup(editing: Item.self, contentType: .rot) {
ContentView()
}
}
}
struct ContentView: View {
@Environment(\.modelContext) private var modelContext
@Query private var items: [Item]
var body: some View {
Button("+", action: {modelContext.insert(Item(name: "test", kind: Item.Kind.function))})
}
}
```
3/5
```
@Model
final class Item {
var name: String
var kind: Kind
enum Kind: Int, Codable {
case function
case module
}
init(name: String, kind: Kind) {
self.name = name
self.kind = kind
}
}
import UniformTypeIdentifiers
extension UTType {
static var rot = UTType(exportedAs: "cafe.droid.rot")
}
```
Filetype set up in xcode as described here: https://developer.apple.com/videos/play/wwdc2023/10154?time=939
4/5
Totally understand I'm probably throwing more info at you here than you probably really want. I'm pretty much convinced that this is just an apple bug, and not a case of me holding it wrong.
I appreciate you looking at it, but don't feel obliged to.
5/5
@GregMorenz It’s all good, thanks for sharing. I do know that there are some unreleased fixes to the compiler that have yet to be incorporated into the Beta.
I’ve been playing with it myself for about a month and faced a number of issues with #swiftdata. But, in general, I appreciate the simplification of the syntax and the ease of declaring model classes and fetching from them.
@natemartinsf I didn't. I concluded that enum's just weren't properly supported in SwiftData and moved on without them in the model struct.
Which was fine for the app I was prototyping, the enum I wanted was just describing a string in the data model anyways, so I can calculate it at runtime. It certainly seems like a pretty big oversight from apple though.
@GregMorenz Yeah, I hope they fix it. I found a similar workaround for enums (store the raw value and create the enum as needed)
Unfortunately I’m running into the same issue with including a custom struct in my model, which I haven’t found a workaround yet.
Severely limits the ability to do any sort of complex model unfortunately. I guess I’ll wait for beta 6!
Greg
AJ
Sixten Otto
Jon Duenas
Kevin
Nate Martin