public async Task OnGetAsync(int?id, int?courseID)
{
Instructor = new InstructorIndexData();
Instructor.Instructors = await _context.Instructors
.Include(i => i.OfficeAssignment)
.Include(i => i.CourseAssignments)
.ThenInclude(i => i.Course)
.ThenInclude(i => i.Department)
//.Include(i => i.CourseAssignments)
// .ThenInclude(i => i.Course)
// .ThenInclude(i => i.Enrollments)
// .ThenInclude(i => i.Student)
// .AsNoTracking()
.OrderBy(i => i.LastName)
.ToListAsync();
if (id != null)
{
InstructorID = id.Value;
Instructor instructor = Instructor.Instructors.Single(
i => i.ID == id.Value);
Instructor.Courses = instructor.CourseAssignments.Select(s => s.Course);
}
if (courseID != null)
{
CourseID = courseID.Value;
var selectedCourse = Instructor.Courses.Where(x => x.CourseID == courseID).Single();
await _context.Entry(selectedCourse).Collection(x => x.Enrollments).LoadAsync();
foreach (Enrollment enrollment in selectedCourse.Enrollments)
{
await _context.Entry(enrollment).Reference(x => x.Student).LoadAsync();
}
Instructor.Enrollments = selectedCourse.Enrollments;
}
}
public async Task <IActionResult> OnPostAsync(int id)
{
if (!ModelState.IsValid)
{
return(Page());
}
var departmentToUpdate = await _context.Departments
.Include(i => i.Administrator)
.FirstOrDefaultAsync(m => m.DepartmentID == id);
// null means Department was deleted by another user.
if (departmentToUpdate == null)
{
return(await HandleDeletedDepartment());
}
// 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(departmentToUpdate)
.Property("RowVersion").OriginalValue = Department.RowVersion;
#endregion
if (await TryUpdateModelAsync <Department>(
departmentToUpdate,
"Department",
s => s.Name, s => s.StartDate, s => s.Budget, s => s.InstructorID))
{
#region snippet_try
try
{
await _context.SaveChangesAsync();
return(RedirectToPage("./Index"));
}
catch (DbUpdateConcurrencyException ex)
{
var exceptionEntry = ex.Entries.Single();
var clientValues = (Department)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 = (Department)databaseEntry.ToObject();
await setDbErrorMessage(dbValues, clientValues, _context);
// Save the current RowVersion so next postback
// matches unless an new concurrency issue happens.
Department.RowVersion = (byte[])dbValues.RowVersion;
// Must clear the model error for the next postback.
ModelState.Remove("Department.RowVersion");
}
#endregion
}
InstructorNameSL = new SelectList(_context.Instructors,
"ID", "FullName", departmentToUpdate.InstructorID);
return(Page());
}
// To protect from overposting attacks, enable the specific properties you want to bind to.
// For more details, see https://aka.ms/RazorPagesCRUD.
public async Task <IActionResult> OnPostAsync(int id)
{
if (!ModelState.IsValid)
{
return(Page());
}
// Fetch current department from DB.
// ConcurrencyToken may have changed.
var departmentToUpdate = await _context.Departments
.Include(i => i.Administrator)
.FirstOrDefaultAsync(m => m.DepartmentID == id);
if (departmentToUpdate == null)
{
return(HandleDeletedDepartment());
}
// Set ConcurrencyToken to value read in OnGetAsync
_context.Entry(departmentToUpdate).Property(
d => d.ConcurrencyToken).OriginalValue = Department.ConcurrencyToken;
if (await TryUpdateModelAsync <Department>(
departmentToUpdate,
"Department",
s => s.Name, s => s.StartDate, s => s.Budget, s => s.InstructorID))
{
try
{
await _context.SaveChangesAsync();
return(RedirectToPage("./Index"));
}
catch (DbUpdateConcurrencyException ex)
{
var exceptionEntry = ex.Entries.Single();
var clientValues = (Department)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 = (Department)databaseEntry.ToObject();
await setDbErrorMessage(dbValues, clientValues, _context);
// Save the current ConcurrencyToken so next postback
// matches unless an new concurrency issue happens.
Department.ConcurrencyToken = (byte[])dbValues.ConcurrencyToken;
// Clear the model error for the next postback.
ModelState.Remove($"{nameof(Department)}.{nameof(Department.ConcurrencyToken)}");
}
}
InstructorNameSL = new SelectList(_context.Instructors,
"ID", "FullName", departmentToUpdate.InstructorID);
return(Page());
}
public async Task UpdateAsync(T entity)
{
_dbContext.Entry(entity).State = EntityState.Modified;
await _dbContext.SaveChangesAsync();
}
public Task Update(T entity)
{
// In case AsNoTracking is used
Context.Entry(entity).State = EntityState.Modified;
return(Context.SaveChangesAsync());
}
public async Task <IActionResult> OnPostAsync(int?id,
[ModelBinder(Name = "Department.RowVersion")] byte[] rowVersion)
{
if (!ModelState.IsValid)
{
return(Page());
}
var departmentToUpdate = await _context.Departments
.Include(i => i.Administrator)
.FirstOrDefaultAsync(m => m.DepartmentID == id);
// null means Department was deleted by another user.
if (departmentToUpdate == null)
{
Department deletedDepartment = new Department();
// Fetch the posted data so we can display it with the error message.
await TryUpdateModelAsync(deletedDepartment);
CopyDepartment(deletedDepartment);
ModelState.AddModelError(string.Empty,
"Unable to save. The department was deleted by another user.");
ViewData["InstructorID"] = new SelectList(_context.Instructors, "ID", "FullName",
Department.InstructorID);
return(Page());
}
var rowVersionParmStr = rowVersion[7];
var rowVersionOrgStr = ((byte[])(_context.Entry(departmentToUpdate)
.Property("RowVersion")).OriginalValue)[7];
// OriginalValue is the current value in the DB when this entity
// was fetched. OriginalValue == rowVersion unless there is a
// concurrency difference. rowVersion is the value when this record
// was fetched by OnGetAsync. Set .OriginalValue = rowVersion to detect a
// concurrency problem. A second postback will make them match.
_context.Entry(departmentToUpdate)
.Property("RowVersion").OriginalValue = rowVersion;
if (await TryUpdateModelAsync <Department>(
departmentToUpdate,
"Department",
s => s.Name, s => s.StartDate, s => s.Budget, s => s.InstructorID))
{
try
{
await _context.SaveChangesAsync();
return(RedirectToPage("./Index"));
}
catch (DbUpdateConcurrencyException ex)
{
var exceptionEntry = ex.Entries.Single();
var clientValues = (Department)exceptionEntry.Entity;
var databaseEntry = exceptionEntry.GetDatabaseValues();
if (databaseEntry == null)
{
ModelState.AddModelError(string.Empty,
"Unable to save changes. The department was deleted " +
"by another user.");
return(Page());
}
var dbValues = (Department)databaseEntry.ToObject();
await setDbErrorMessage(dbValues, clientValues, _context);
var dbRowVers = ((byte[])dbValues.RowVersion)[7];
// Save the current RowVersion so
// it can be posted back to this method in a hidden field.
Department.RowVersion = (byte[])dbValues.RowVersion;
ModelState.Remove("RowVersion");
}
}
ViewData["InstructorID"] = new SelectList(_context.Instructors, "ID", "FullName", departmentToUpdate.InstructorID);
return(Page());
}
public async Task <IActionResult> OnPostAsync(int id)
{
if (!ModelState.IsValid)
{
return(Page());
}
var departmentToUpdate = await _context.Departments
.Include(i => i.Administrator)
.FirstOrDefaultAsync(m => m.DepartmentID == id);
if (departmentToUpdate == null)
{
return(HandleDeletedDepartment());
}
_context.Entry(departmentToUpdate)
.Property("RowVersion").OriginalValue = Department.RowVersion; //отслеживание изменений
if (await TryUpdateModelAsync <Department>(
departmentToUpdate,
"Department",
s => s.Name, s => s.StartDate, s => s.Budget, s => s.InstructorID))
{
try
{
await _context.SaveChangesAsync();
return(RedirectToPage("./Index"));
}
catch (DbUpdateConcurrencyException ex)
{
var exceptionEntry = ex.Entries.Single();
var clientValues = (Department)exceptionEntry.Entity;
var databaseEntry = exceptionEntry.GetDatabaseValues();
if (databaseEntry == null)
{
ModelState.AddModelError(string.Empty, "Сохранение отклонено. " +
"Данные изменены другим пользователем.");
return(Page());
}
var dbValues = (Department)databaseEntry.ToObject();
await setDbErrorMessage(dbValues, clientValues, _context);
// Save the current RowVersion so next postback
// matches unless an new concurrency issue happens.
Department.RowVersion = (byte[])dbValues.RowVersion;
/* код задает для RowVersion новое значение,
* полученное из базы данных. Когда пользователь в следующий раз нажимает кнопку Save (Сохранить),
* перехватываются только те ошибки параллелизма,
* возникшие с момента последнего отображения страницы "Edit" (Редактирование).
*/
// Clear the model error for the next postback.
ModelState.Remove("Department.RowVersion");
/* Оператор ModelState.Remove является обязательным, так как ModelState имеет старое значение RowVersion.
* На странице Razor значение ModelState для поля имеет приоритет над значениями свойств модели,
* если они присутствуют вместе.
*/
}
}
InstructorNameSL = new SelectList(_context.Instructors,
"ID", "FullName", departmentToUpdate.InstructorID);
return(Page());
}
