public async Task <IActionResult> OnPostAsync()
{
if (!ModelState.IsValid)
{
return(Page());
}
_context.Students.Add(Student);
await _context.SaveChangesAsync();
return(RedirectToPage("./Index"));
}
public async Task <IActionResult> OnPostAsync(int?id)
{
if (id == null)
{
return(NotFound());
}
Student = await _context.Students.FindAsync(id);
if (Student != null)
{
_context.Students.Remove(Student);
await _context.SaveChangesAsync();
}
return(RedirectToPage("./Index"));
}
public async Task <IActionResult> OnPostAsync(int id)
{
if (!ModelState.IsValid)
{
return(Page());
}
var studentToUpdate = await _context.Students
.FirstOrDefaultAsync(m => m.Id == id);
// null means Department was deleted by another user.
if (studentToUpdate == null)
{
return(await HandleDeletedStudent());
}
// Update the RowVersion to the value when this entity was
// fetched. If the entity has been updated after it was
// fetched, RowVersion won't match the DB RowVersion and
// a DbUpdateConcurrencyException is thrown.
// A second postback will make them match, unless a new
// concurrency issue happens.
_context.Entry(studentToUpdate)
.Property("RowVersion").OriginalValue = Student.RowVersion;
if (await TryUpdateModelAsync <Student>(
studentToUpdate,
"Student",
s => s.Name, s => s.BirthDate))
{
try
{
await _context.SaveChangesAsync();
return(RedirectToPage("./Index"));
}
catch (DbUpdateConcurrencyException ex)
{
var exceptionEntry = ex.Entries.Single();
var clientValues = (Student)exceptionEntry.Entity;
var databaseEntry = exceptionEntry.GetDatabaseValues();
if (databaseEntry == null)
{
ModelState.AddModelError(string.Empty, "Unable to save. " +
"The department was deleted by another user.");
return(Page());
}
var dbValues = (Student)databaseEntry.ToObject();
await SetDbErrorMessage(dbValues, clientValues, _context);
// Save the current RowVersion so next postback
// matches unless an new concurrency issue happens.
Student.RowVersion = (byte[])dbValues.RowVersion;
// Must clear the model error for the next postback.
ModelState.Remove("Student.RowVersion");
}
}
return(Page());
}
