With Core Data and SwiftUI we can use @SectionedFetchRequest. Does SwiftData support something similar to @SectionedFetchRequest?
For example, I want to create a lazy-loaded list that groups posts by their date.
@Model Post {
let title: String
let dateString: String // YYYY-MM-DD
let createdAt: Date
}
@SectionedFetchRequest(
entity: \Post.self,
sectionIdentifier: \Post.dateString,
sortDescriptors: [\Post.createdAt]
)
var postsByDate: SectionedFetchResults
ForEach(postsByDate) { section in
Section(header: Text(section.id)) {
ForEach(section) { post in
PostView(post)
}
}
}
magnuti
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
Last seen
User for
From
Norway
Post
Replies
Boosts
Views
Activity
Doing a batch delete on a many-to-one relationship seems to throw this error
CoreData: error: Unhandled opt lock error from executeBatchDeleteRequest Constraint trigger violation: Batch delete failed due to mandatory OTO nullify inverse on Student/school and userInfo {
NSExceptionOmitCallstacks = 1;
NSLocalizedFailureReason = "Constraint trigger violation: Batch delete failed due to mandatory OTO nullify inverse on Student/school";
"_NSCoreDataOptimisticLockingFailureConflictsKey" = (
);
}
If I try to delete the School in the one-to-many relationship, both the school and the students are deleted as expected.
However, If I try to delete all students the error is thrown. I would expect all students to be removed, while keeping the School intact.
Do SwiftData support this?
import XCTest
import SwiftData
@Model
class School {
var name: String
@Relationship(deleteRule: .cascade, inverse: \Student.school)
var students: [Student] = []
init(name: String) {
self.name = name
}
}
@Model
class Student {
var name: String
var school: School?
init(name: String) {
self.name = name
}
}
final class Test: XCTestCase {
func testScenario() throws {
let config = ModelConfiguration(isStoredInMemoryOnly: true)
let modelContainer = try ModelContainer(for:
School.self,
Student.self,
configurations: config
)
let context = ModelContext(modelContainer)
context.autosaveEnabled = false
let school = School(name: "school")
context.insert(school)
let student1 = Student(name: "1")
let student2 = Student(name: "2")
context.insert(student1)
context.insert(student2)
student1.school = school
student2.school = school
XCTAssertEqual(school.students.count, 2)
XCTAssertEqual(student1.school?.id, school.id)
XCTAssertEqual(student2.school?.id, school.id)
try context.save()
let newContext = ModelContext(modelContainer)
// try newContext.delete(model: School.self) // This works
try newContext.delete(model: Student.self) // This one fails
}
}
Given the code below the students array on the school is not being updated. Why?
Since the relationship is explicit and non-optional I would expect this to work.
import XCTest
import SwiftData
@Model
class School {
var name: String
@Relationship(deleteRule: .cascade, inverse: \Student.school)
var students: [Student]
init(name: String, students: [Student]) {
self.name = name
self.students = students
}
}
@Model
class Student {
var name: String
var school: School
init(name: String, school: School) {
self.name = name
self.school = school
}
}
final class Test: XCTestCase {
func testScenario() throws {
let modelContainer = try ModelContainer(for:
School.self,
Student.self
)
let context = ModelContext(modelContainer)
context.autosaveEnabled = false
let school = School(name: "school", students: [])
context.insert(school)
let student1 = Student(name: "1", school: school)
let student2 = Student(name: "2", school: school)
context.insert(student1)
context.insert(student2)
XCTAssertEqual(school.students.count, 2) // XCTAssertEqual failed: ("0") is not equal to ("2")
}
}