add ModelContainerPreview conecept, move SampleData, fix Exercise, ExerciseUnit, ExerciseType

WorkoutsPlus/SampleData/SampleData.swift

@@ -0,0 +1,84 @@
+//
+//  SampleData.swift
+//  WorkoutsPlus
+//
+//  Created by Felix Förtsch on 17.08.24.
+//
+
+import Foundation
+import SwiftData
+
+// This is taken from the Animals example
+extension ModelContainer {
+		static var sample: () throws -> ModelContainer = {
+				let schema = WorkoutsPlusApp.swiftDataSchema
+				let configuration = ModelConfiguration(isStoredInMemoryOnly: true)
+				let container = try ModelContainer(for: schema, configurations: [configuration])
+				Task { @MainActor in
+						SampleData.insertSampleData(into: container.mainContext)
+				}
+				return container
+		}
+}
+
+@MainActor // With your annotation, you’re declaring that all code in this class must run on the main actor, including access to the mainContext property. Since all the SwiftUI code in an app runs on the main actor by default, you’ve satisfied the condition.
+class SampleData {
+		static let shared = SampleData()
+		
+		let modelContainer: ModelContainer
+		
+		var context: ModelContext {
+				modelContainer.mainContext
+		}
+		
+		private init() {
+				let schema = WorkoutsPlusApp.swiftDataSchema
+				let modelConfiguration = ModelConfiguration(schema: schema, isStoredInMemoryOnly: true)
+				
+				do {
+						modelContainer = try ModelContainer(for: schema, configurations: [modelConfiguration])
+						SampleData.insertSampleData(into: context)
+				} catch {
+						fatalError("Could not create ModelContainer: \(error)")
+				}
+		}
+}
+
+
+extension SampleData {
+		static func insertSampleData(into context: ModelContext) {
+				for exerciseType in ExerciseType.sampleData {
+						context.insert(exerciseType)
+				}
+				
+				for exerciseUnit in ExerciseUnit.sampleData {
+						context.insert(exerciseUnit)
+				}
+				
+				for exercise in Exercise.sampleDataRecommendedRoutine {
+						context.insert(exercise)
+				}
+				
+				for exercise in Exercise.sampleDataRings {
+						context.insert(exercise)
+				}
+				
+				for workoutItem in WorkoutItem.sampleDataRecommendedRoutine {
+						context.insert(workoutItem)
+				}
+				
+				for workoutItem in WorkoutItem.sampleDataRings {
+						context.insert(workoutItem)
+				}
+				
+				for workout in Workout.sampleData {
+						context.insert(workout)
+				}
+				
+				do {
+						try context.save()
+				} catch {
+						print("Sample data context failed to save.")
+				}
+		}
+}