SwiftData how to delete data from an entity

Question

I am working on migrating my code into SwiftData and can't seem to find any good answers on how to delete the data in that entity. In Swift I had this function created:

class func deleteEntity(entity: String) {
  let fetchRequest1: NSFetchRequest<NSFetchRequestResult> = NSFetchRequest(entityName: entity)//entity.fetchRequest()
  let batchDeleteRequest1 = NSBatchDeleteRequest(fetchRequest: fetchRequest1)
  _ = try?  PersistanceController.shared.container.viewContext.execute(batchDeleteRequest1)
  print("Deleting coredata entity: \(entity)")
}

in Xcode 15 (beta) I have my context:

container = try ModelContainer(for: [SectionsSD.self, ArticleSD.self])
let context = ModelContext(container)

I want to delete the content that's in ArticlesSD.self I've been told to look at using: ModelContext.delete(_:) or ModelContext.delete(model:where:includesubentities:), but I can't figure out the right syntax on how to use these

Any help would be appreciated. An example or sample code would be helpful.

Answer 1

The signature of the context.delete changed to

delete(model: T.Type, where predicate: Predicate? = nil, includeSubclasses: Bool = true)

Therefore, the code of Tom Harrington has to be adapted a bit to accommodate these changes. What he says still holds true, the idea is the same. The following extension allows to conveniently delete all entries of a Type

extension ModelContext {
    func deleteAll<T>(model: T.Type) where T : PersistentModel {
        do {
            let p = #Predicate<T> { _ in true }
            try self.delete(model: T.self, where: p, includeSubclasses: false)
            print("All of \(model.self) cleared !")
        } catch {
            print("error: \(error)")
        }
    }
}

It can be called like

modelContext.deleteAll(model: ArticlesSD.self)

Answer 2

I haven't been able to verify this for sure but it looks like what you want is

context.delete(model: ArticlesSD.self)

There are other arguments for this function but one is optional and one has a default value. If you want to be clear about them, you could write it as

context.delete(model: ArticlesSD.self, where: NSPredicate(value: true), includeSubentities: false)

The predicate tells the context which items to delete, and a "true" predicate means to delete all of them. The subentries argument doesn't matter unless you've created sub-entities (and you would know if you did).