Question 87429 in ASP.NET Question posted in
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Model binding / ViewModel binding in ASP.Net Core MVC

Let’s start with simple code:

public class SomeViewModel 
{
    public int State { get; set; }
}

public class SomeController : Controller
{
    public IActionResult DoSomething(int state)
    {
        var viewModel = new SomeViewModel();
        
        if(state % 2 == 0)
            viewModel.State = state * 2;
        else
            viewModel.State = state;
        
        return View("MyView", viewModel)
    }
}

MyView.cshtml:

@model SomeViewModel;

...
    <form method="get" asp-action="BlablaAction" asp-controller="OtherController">
        <input asp-for="State">
        <button type="submit">Save</button>
    </form>

...

I’m making requests:

/some/dosomething?state=4 => input value = 4

/some/dosomething?state=5 => input value = 5

/some/dosomething?state=6 => input value = 6

/some/dosomething?state=7 => input value = 7

but according to my logic in DoSomething action it should be:

/some/dosomething?state=4 => input value = 8

/some/dosomething?state=5 => input value = 5

/some/dosomething?state=6 => input value = 12

/some/dosomething?state=7 => input value = 7

My question is: Why input value is assigned to query param instead of property of passed model object…
And second thing I know i can change name of param from state to param1 but maybe there is other way to do it…
I’ve read 2 books about ASP.net core and haven’t encounter anything about that.

Tags:

2

Answers


  1. 0

    if your form method is "get" inputs send as query string but if you want to post them as form you shoule post your form and assign type "post" to your form method.

      <form method="post" asp-action="DoSomething" asp-controller="Some">
        <input asp-for="State">
        <button type="submit">Save</button>
    </form>

    in this code State bind to your SomeViewModel if your parameter in action be type of SomeViewModel.

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  2. 0

    When<input asp-for="">label complied to HTML,it get value from ModelState before get value from your viewmodel,so you could clear the value in ModelState

    public IActionResult DoSomething(int state)

        {
            var viewModel = new SomeViewModel();

            if (state % 2 == 0)
            {
                viewModel.State = state * 2;
                ModelState.Clear();
            }
            else
                viewModel.State = state;
           
            return View(viewModel);
        }

    Also，you could keep the codes in controller,and just modify the label:

    <input type="number" data-val="true" data-val-required="The State field is required." id="State" name="State" value="@Model.State">
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