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Wednesday, March 12, 2014
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About the Default Edit Action Methods and View in MVC

6:54 PMWednesday, March 12, 2014
Earlier article was about the create action of the controller, which in other words used to create/insert a record into the database using an MVC application. This article have a brief description about Edit action created by default, it’s Get and post method.

According to name, Get method is used to get a particular model according to passed id and return to the view that will show that model. The below code will return the details of a particular Student. User can edit particular information in the textboxes shown on the form and click on submit button.

// GET: /Student/Edit
public ActionResult Edit(int id = 0)
{
Student student = db.Students.Find(id); //db is object of our context class
if (student == null)
{
return HttpNotFound();
}
return View(student);
}
The first line is used to find the existing record by the primary key (id) passed as parameter. Checking all the required condition, it will return the selected student on the Edit view. After clicking on the submit button, compiler goes to the post method of the same action i.e. Post Edit action, as written below:

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(Student student)
{
if (ModelState.IsValid)
{
db.Entry(student).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(student);
}
This method have a parameter of type student that was passed through the Get method of the same action. The first two line of this code are attributes used to tell the compiler about this method i.e. this is post method and validates fields on submit method. In the create action we have add the student, but in this case we need to just change the state to Modified to update all the fields provided to the user to edit on the view.

@using (Html.BeginForm()) {
@Html.AntiForgeryToken()
@Html.ValidationSummary(true)
@Html.HiddenFor(model => model.Id)
<div class="editor-label">
@Html.LabelFor(model => model.Name)
</div>
<div class="editor-field">
@Html.EditorFor(model => model.Name)
@Html.ValidationMessageFor(model => model.Name)
</div>……………….
……………….
……………….

This view is strongly typed view because of the first line and have all the fields of student class (only name is shown here, remaining are something like this).

So turn back on our previous discussion that was about the post Edit action. This action will then check the model is valid or not (Validation). If valid then it will update this student in the student table and then save the changes to the database. If not it will return to the same page with the errors generated.

The last line will return to the same action i.e. Edit with the model passed as parameter and of course with validation errors, you can check this to not enter some fields in the form and submit the data.
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