Issue
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.
Solution
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">
Answered By – Ruikai Feng
Answer Checked By – David Marino (BugsFixing Volunteer)