Introduction
In .NET framework 4.5 asynchronous programming concept has been introduced. In this regard, .NET introduced two keyword async and await. It is much easier to implement than the multi-threading concept. The .NET Framework 4 introduced an asynchronous programming concept referred to as a Task and ASP.NET MVC 4 supports Task. In this article I will show you a simple CRUD operation using asynchronous programming by async, await and Task.
A simple overview on “async, await, Task” Keyword
async
The async modifier indicates that the method, lambda expression, or anonymous method will work asynchronously.
Method with async modifier also called async method.
An async method provides a convenient way to do potentially long-running work without blocking the caller’s thread.
The caller of an async method can resume its work without waiting for the async method to finish.
Typically, a method modified by the async keyword contains at least one await expression or statement.
await
Typically await keyword used to free a thread
The await operator is applied to a task in an asynchronous method to suspend the execution of the method until the awaited task completes.
The asynchronous method in which await is used must be modified by the async keyword. Such a method, defined by using the async modifier, and usually containing one or more await expressions, is referred to as an async method.
The task to which the await operator is applied typically is the return value from a call to a method that
implements.
Task
The main types are System.Threading.Tasks.Task
Represents an asynchronous operation that can be waited on and cancelled
System.Threading.Tasks.Task, which is a task that can return a value.
Here I implement async modifier to a CRUD operation on Employee Object. Let’s start. Tools and Technology used
I used following tools and technology to develop the project –
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
public string NickName { get; set; }
public string Designation { get; set; }
public string Dept { get; set; }
}
Step 4: Create a DbContext name EmployeeDBContext in Model folder.
public class EmployeeDBContext : DbContext
{
public EmployeeDBContext()
: base("DefaultConnection")
{
}
public DbSet Employees { get; set; }
}
Step 5: Create a controller name – EmployeeController. Select template “MVC5 Controller with views, using entity framework”. EmployeeController will create in Controller folder and related views will be created in Views/Employee folder. At the time of creating controller – mark use async controller action.
Step 6: Employee Controller is given below. A simple difference over normal method is –
used async keyword in Action Method.
Used Task instead of typical ActionResult
And used await keyword in any operation.
public class EmployeeController : Controller
{
private EmployeeDBContext db = new EmployeeDBContext();
// GET: /Employee/
public async Task Index()
{
return View(await db.Employees.ToListAsync());
}
// GET: /Employee/Details/5
public async Task Details(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Employee employee = await db.Employees.FindAsync(id);
if (employee == null)
{
return HttpNotFound();
}
return View(employee);
}
// GET: /Employee/Create
public ActionResult Create()
{
return View();
}
// POST: /Employee/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task Create([Bind(Include="Id,Name,NickName,Designation,Dept")] Employee employee)
{
if (ModelState.IsValid)
{
db.Employees.Add(employee);
await db.SaveChangesAsync();
return RedirectToAction("Index");
}
return View(employee);
}
// GET: /Employee/Edit/5
public async Task Edit(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Employee employee = await db.Employees.FindAsync(id);
if (employee == null)
{
return HttpNotFound();
}
return View(employee);
}
// POST: /Employee/Edit/5
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task Edit([Bind(Include="Id,Name,NickName,Designation,Dept")] Employee employee)
{
if (ModelState.IsValid)
{
db.Entry(employee).State = EntityState.Modified;
await db.SaveChangesAsync();
return RedirectToAction("Index");
}
return View(employee);
}
// GET: /Employee/Delete/5
public async Task Delete(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Employee employee = await db.Employees.FindAsync(id);
if (employee == null)
{
return HttpNotFound();
}
return View(employee);
}
// POST: /Employee/Delete/5
[HttpPost, ActionName("Delete")]
[ValidateAntiForgeryToken]
public async Task DeleteConfirmed(int id)
{
Employee employee = await db.Employees.FindAsync(id);
db.Employees.Remove(employee);
await db.SaveChangesAsync();
return RedirectToAction("Index");
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
db.Dispose();
}
base.Dispose(disposing);
}
}
Step 7: Views – After selecting and executing template views are automatically created. Here is the views for CRUD operation of Employee.
