How to Update Model in ASP NET MVC 6?

Scenario: How to update a model?

ASP MVC 6

I am trying to update a model. For passing the model information to the client(browser/app) I am using the DTO.

Question 1: For updating, should I post the whole object back?

Question 2: Is there a way I can easily pass only the information that is updated? If yes, how?

Question 3: Can I use JSON Patch for updation?

回答1:

Question 2: Is there a way I can easily pass only the information that is updated? If yes, how?

Yes. You should create a view model which should have only those properties needed for the view.

Let's assume your use case is to build a view which allows user to edit only their last name.

public class EditUserViewModel
{
  public int Id {set;get;}
  public string LastName {set;get;}
}

And in your Get

public ActionResult Edit(int id)
{
  var user = yourUserRepository.GetUser(id);
  if(user!=null)
  {
   var v = new EditUserViewModel { Id=id,LastName=user.LastName};
   return View(v);
  }
  return View("NotFound");
}

And the view

@model EditUserViewModel
@using(Html.BeginForm())
{
  @Html.TextBoxFor(s=>S.LastName)
  @Html.HiddenFor(s=>s.Id)
  <input type="submit" id="saveBtn" />
}

and your HttpPost action

[HttpPost]
public ActionResult Edit(EditUserViewModel model)
{
   // Since you know you want to update the LastName only, 
   // read model.LastName and use that
   var existingUser = yourUserRepository.GetUser(model.Id);
   existingUser.LastName = model.LastName;
   yourUserRepository.Save();
   // TO DO:  redirect to success page
}

Assuming yourUserRepository is an object of your data access classes abstraction.

Question 1: For updating, should I post the whole object back?

Depends on what you want from the end user. With this view model approach, It is going to post only the Id and LastName and that is our use case.

Can I use JSON Patch for updating?

Since you are only sending the data which needs to be updated (partial data), you should be fine.

If you want,you may simply serialize your form data(which has only Id and LastName) and use jQuery post method to send it to your server.

$(function(){

  $("#saveBtn").click(function(e){

    e.preventDefault(); //prevent default form submit

    var _form=$(this).closest("form");
    $.post(_form.attr("action"),_form.serialize(),function(res){
      //do something with the response.
    });

  });

});

To prevent overposting, you can use a binding whitelist using Bind attribute on your HttpPost action method. But the safest strategy is to use a view model class that exactly matches what the client is allowed to send.

回答2:

Instead of this