CoreData and SwiftUI: Context in environment is not connected to a persistent store coordinator

Question

I am trying to teach myself Core Data by building a homework managing app. My code builds fine and the app runs okay until I try to add a new assignment to the list. I get t

Answer 1

You're not actually saving the context. You should be executing the following:

let newAssignment = Assignment(context: self.moc)
newAssignment.name = self.name
newAssignment.hasDueDate = self.hasDueDate
newAssignment.dueDate = self.dueDate
newAssignment.statusString = Status.incomplete.rawValue
newAssignment.course = self.course

do {
    try self.moc.save()
} catch {
    print(error)
}

Also your @FetchRequest(...) could look like this:

@FetchRequest(fetchRequest: CourseItem.getCourseItems()) var courses: FetchedResults

You can modify your CourseItem class to handle the sortDescriptors like the following:

public class CourseItem: NSManagedObject, Identifiable {
    @NSManaged public var name: String?
    @NSManaged public var dueDate: Date?
    // ...etc
}

extension CourseItem {
    static func getCourseItems() -> NSFetchRequest {
        let request: NSFetchRequest = CourseItem.fetchRequest() as! NSFetchRequest

        let sortDescriptor = NSSortDescriptor(key: "dueDate", ascending: true)

        request.sortDescriptors = [sortDescriptor]

        return request
    }
}

Then you would modify your ForEach(...) like the following and can also handle the deletion of items quite easily as well:

ForEach(self.courses) { course in
    // ...
}.onDelete { indexSet in
    let deleteItem = self.courses[indexSet.first!]
    self.moc.delete(deleteItem)

    do {
        try self.moc.save()
    } catch {
        print(error)
    }
}

One thing you want to ensure is that the "Class Name" is set to "CourseItem", which matches the CourseItem class we created earlier.

Simply click ENTITIES in your .xcdatamodeId file and set everything to the following (including Module to "Current Product Module" and Codegen to "Manual/None"):