使用EFCore处理并发冲突

public class Department
{
     public int Id { get; set;}
     public int? InstructorId{ get; set; }
     public ICollection<Course> Courses {get; set; }

     [Timestamp]
     public byte[] RowVersion{get; set; }
}

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Edit(int? id, byte[]rowVersion)
{
       if(id==null)
       {
              return NoFound();
       }
       //先查一下数据是否存在
       var department= await 
       _context.Departments.Include(a=>a.Administrator)
                  .SingleOrDefaultAsync(a=>a.Id==id);
   
       if(department==null)
       {
              var deletedDepartment=new Department();
              await TryUpdateModeAsync(deletedDepartment);
              ModelState.AddModelError(string.Empty,"无法进行数据的修改，该部门信息已经被其他人删除！);
              ViewData["InstructorId"]=new SelectList(_context.Instructors, "Id","RealName",deletedDepartment);
              return View(deletedDepartment);              
       }

        //将RowVersion标志原来的值变更为新的值
       _context.Entry(department).Property("RowVersion").OriginalValue = rowVersion; 

        if(await TryUpdateModelAsync<Department>(department, a=>a.Name, a=>a.StartDate, a=>a.Budge(a=>a.InstructorId))
        {
              try
              {

              }
               catch()
               {
                     
               }
        }
}