Can i add a parent record and a child record using the same _context.SaveChangesAsync() - asp.net-core

Question

I have the following 2 Parent/Child objects:-
public Submission()
{
SubmissionQuestionSubmission = new HashSet<SubmissionQuestionSubmission>();
}
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Npi { get; set; }
public bool Independent { get; set; }
public string Comment { get; set; }
public virtual ICollection<SubmissionQuestionSubmission> SubmissionQuestionSubmission { get; set; }
}
public partial class SubmissionQuestionSubmission
{
public int SubmissionQuestionId { get; set; }
public int SubmissionId { get; set; }
public string Answer { get; set; }
public virtual Submission Submission { get; set; }
}
and i created the following view model:-
public class SubmissionCreate
{
public Submission Submission {set; get;}
public IList<SubmissionQuestion> SubmissionQuestion { set; get; }
public IList<SubmissionQuestionSubmission> SubmissionQuestionSubmission { set; get; }
}
where i have the following action method to add a parent record (submission) and a child record (SubmissionQuestionSubmission ), but to do so, i have to issue 2 save requests to the database, one to save the parent and get its ID, while the other to save the child record and assign it the parent ID, as follow:-
public async Task<IActionResult> Create(SubmissionCreate sc)//Bind("Id,FirstName,LastName,Npi,Independent,Comment")]
{
if (ModelState.IsValid)
{
var newsubmission = _context.Submission.Add(sc.Submission);
await _context.SaveChangesAsync();
foreach (var v in sc.SubmissionQuestionSubmission)
{
v.SubmissionId = sc.Submission.Id;
_context.SubmissionQuestionSubmission.Add(v);
}
await _context.SaveChangesAsync();
TempData["message"] = "Thank You.. Your request has been submitted...";
return View("Confirmation");
}
return View(sc);
}
so my question is if i can do the above job, using one save statement instead of 2?

Answer 1

You don't need use two SaveChanges. You can assign newsubmission into Submission property instead of v.SubmissionId = sc.Submission.Id;.
In this case Id and ForeignKey created automatically by EF Core
var newsubmission = _context.Submission.Add(sc.Submission);
foreach (var v in sc.SubmissionQuestionSubmission)
{
v.Submission = newsubmission;
_context.SubmissionQuestionSubmission.Add(v);
}
await _context.SaveChangesAsync();
Another way
sc.Submission.SubmissionQuestionSubmission = new List<SubmissionQuestionSubmission>();
foreach (var v in sc.SubmissionQuestionSubmission)
{
sc.Submission.SubmissionQuestionSubmission.Add(v)
}
_context.Submission.Add(sc.Submission);
await _context.SaveChangesAsync();