I get this message when trying to save my Models.

CoreData: error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x303034540> , I/O error for database at /var/mobile/Containers/Data/Application/726ECA8C-6C67-4BFE-89E7-AFD8A83CAA5D/Library/Application Support/default.store.  SQLite error code:1, 'no such table: ZCALENDARMODEL' with userInfo of {
    NSFilePath = "/var/mobile/Containers/Data/Application/726ECA8C-6C67-4BFE-89E7-AFD8A83CAA5D/Library/Application Support/default.store";
    NSSQLiteErrorDomain = 1;
}
SwiftData.DefaultStore save failed with error: Error Domain=NSCocoaErrorDomain Code=256 "The file “default.store” couldn’t be opened." UserInfo={NSFilePath=/var/mobile/Containers/Data/Application/726ECA8C-6C67-4BFE-89E7-AFD8A83CAA5D/Library/Application Support/default.store, NSSQLiteErrorDomain=1}

The App has Recipes and Calendars and the user can select a Recipe for each Calendar day. The recipe should not be referenced, it should be saved by SwiftData along with the Calendar.

import SwiftUI
import SwiftData

enum CalendarSource: String, Codable {
    case created
    case imported
}

@Model
class CalendarModel: Identifiable, Codable {
    var id: UUID = UUID()
    var name: String
    var startDate: Date
    var endDate: Date
    var recipes: [String: RecipeData] = [:]
    var thumbnailData: Data?
    var source: CalendarSource?

    // Computed Properties
    var daysBetween: Int {
        let days = Calendar.current.dateComponents([.day], from: startDate.midnight, to: endDate.midnight).day ?? 0
        return days + 1
    }

    var allDates: [Date] {
        startDate.midnight.allDates(upTo: endDate.midnight)
    }

    var thumbnailImage: Image? {
        if let data = thumbnailData, let uiImage = UIImage(data: data) {
            return Image(uiImage: uiImage)
        } else {
            return nil
        }
    }

    // Initializer
    init(name: String, startDate: Date, endDate: Date, thumbnailData: Data? = nil, source: CalendarSource? = .created) {
        self.name = name
        self.startDate = startDate
        self.endDate = endDate
        self.thumbnailData = thumbnailData
        self.source = source
    }

    // Convenience initializer to create a copy of an existing calendar
    static func copy(from calendar: CalendarModel) -> CalendarModel {
        let copiedCalendar = CalendarModel(
            name: calendar.name,
            startDate: calendar.startDate,
            endDate: calendar.endDate,
            thumbnailData: calendar.thumbnailData,
            source: calendar.source
        )
        // Copy recipes
        copiedCalendar.recipes = calendar.recipes.mapValues { $0 }
        return copiedCalendar
    }

    // Codable Conformance
    private enum CodingKeys: String, CodingKey {
        case id, name, startDate, endDate, recipes, thumbnailData, source
    }

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(UUID.self, forKey: .id)
        name = try container.decode(String.self, forKey: .name)
        startDate = try container.decode(Date.self, forKey: .startDate)
        endDate = try container.decode(Date.self, forKey: .endDate)
        recipes = try container.decode([String: RecipeData].self, forKey: .recipes)
        thumbnailData = try container.decodeIfPresent(Data.self, forKey: .thumbnailData)
        source = try container.decodeIfPresent(CalendarSource.self, forKey: .source)
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(id, forKey: .id)
        try container.encode(name, forKey: .name)
        try container.encode(startDate, forKey: .startDate)
        try container.encode(endDate, forKey: .endDate)
        try container.encode(recipes, forKey: .recipes)
        try container.encode(thumbnailData, forKey: .thumbnailData)
        try container.encode(source, forKey: .source)
    }
}

import SwiftUI

struct RecipeData: Codable, Identifiable {
    var id: UUID = UUID()
    var name: String
    var ingredients: String
    var steps: String
    var thumbnailData: Data?

    // Computed property to convert thumbnail data to a SwiftUI Image
    var thumbnailImage: Image? {
        if let data = thumbnailData, let uiImage = UIImage(data: data) {
            return Image(uiImage: uiImage)
        } else {
            return nil  // No image
        }
    }
    
    init(recipe: RecipeModel) {
        self.name = recipe.name
        self.ingredients = recipe.ingredients
        self.steps = recipe.steps
        self.thumbnailData = recipe.thumbnailData
    }
}

import SwiftUI
import SwiftData

@Model
class RecipeModel: Identifiable, Codable {
    var id: UUID = UUID()
    var name: String
    var ingredients: String
    var steps: String
    var thumbnailData: Data? // Store the image data for the thumbnail
    static let fallbackSymbols = ["book.pages.fill", "carrot.fill", "fork.knife", "stove.fill"]

    // Computed property to convert thumbnail data to a SwiftUI Image
    var thumbnailImage: Image? {
        if let data = thumbnailData, let uiImage = UIImage(data: data) {
            return Image(uiImage: uiImage)
        } else {
            return nil  // No image
        }
    }

    // MARK: - Initializer
    init(name: String, ingredients: String = "", steps: String = "", thumbnailData: Data? = nil) {
        self.name = name
        self.ingredients = ingredients
        self.steps = steps
        self.thumbnailData = thumbnailData
    }

    // MARK: - Copy Function
    func copy() -> RecipeModel {
        RecipeModel(
            name: self.name,
            ingredients: self.ingredients,
            steps: self.steps,
            thumbnailData: self.thumbnailData
        )
    }

    // MARK: - Codable Conformance
    private enum CodingKeys: String, CodingKey {
        case id, name, ingredients, steps, thumbnailData
    }

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(UUID.self, forKey: .id)
        name = try container.decode(String.self, forKey: .name)
        ingredients = try container.decode(String.self, forKey: .ingredients)
        steps = try container.decode(String.self, forKey: .steps)
        thumbnailData = try container.decodeIfPresent(Data.self, forKey: .thumbnailData)
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(id, forKey: .id)
        try container.encode(name, forKey: .name)
        try container.encode(ingredients, forKey: .ingredients)
        try container.encode(steps, forKey: .steps)
        try container.encode(thumbnailData, forKey: .thumbnailData)
    }
}

I tried to create the RecipeData so that selecting Recipes doesnt interfere with the RecipeModels.