ASP.NET Core MVC validate not required fields - asp.net-mvc

Question

My page is validating a field that is not required when I submit, even though there is no validation configured for this field.
Create.cshtml
#model Lawtech.App.ViewModels.ProcessoViewModel
#{
ViewData["Title"] = "Novo processo";
}
<h3 style="padding-top: 10px">#ViewData["Title"] </h3>
<hr />
<div class="row">
<div class="col-md-12">
<form asp-action="Create">
<div asp-validation-summary="ModelOnly" class="text-danger"></div>
<div class="row">
<div class="form-group col-md-4">
<label asp-for="Numero" class="control-label"></label>
<input asp-for="Numero" class="form-control" />
<span asp-validation-for="Numero" class="text-danger"></span>
</div>
<div class="form-group col-sm-4">
<label asp-for="IdArea" class="control-label"></label>
<div class="input-group">
<select id="slcArea" asp-for="IdArea" class="form-control select2"></select>
<div class="input-group-btn">
<a asp-action="CreateArea" class="btn btn-info" style="border-radius:0 0.25rem 0.25rem 0" data-modal="">
<span class="fa fa-plus"></span>
</a>
</div>
</div>
</div>
</div>
<div class="row">
<div class="form-group col-md-6 mt-4">
<input type="submit" value="Cadastrar" class="btn btn-sm btn-primary" />
<a class="btn btn-sm btn-info" asp-action="Index">Voltar</a>
</div>
</div>
</form>
</div>
</div>
<div id="myModal" class="modal fade in">
<div class="modal-dialog">
<div class="modal-content">
<div id="myModalContent"></div>
</div>
</div>
</div>
ViewModel
public class ProcessoViewModel
{
[Key]
public int Id { get; set; }
[DisplayName("Número")]
[Required(ErrorMessage = "O campo número é obrigatório")]
public string Numero { get; set; }
[DisplayName("Área")]
public int IdArea { get; set; }
}
Controller
In Controller Create method, nothing happens, because all validation takes place on the client side.
[Route("novo-processo")]
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create(ProcessoViewModel processoViewModel)
{
try
{
if (!ModelState.IsValid) return View(processoViewModel);
await _processoBLL.Insert(_mapper.Map<ProcessoDTO>(processoViewModel));
if (!ValidOperation()) return View(processoViewModel);
return RedirectToAction(nameof(Index));
}
catch
{
return View();
}
}
Inspecting in Chrome I see this generated html for the field that I didn't require validation, I don't know if it could be something related to Jquery.Unobtrusive but I can't remove it either because other fields will be validated.
<select id="slcArea" class="form-control select2 select2-hidden-accessible input-validation-error" data-val="true" data-val-required="The Área field is required." name="IdArea" data-select2-id="slcArea" tabindex="-1" aria-hidden="true" aria-describedby="slcArea-error" aria-invalid="true"></select>
Why is this validation taking place that I have not defined the field as required?

Answer 1

Not nullable properties (that is properties with value types) are always required. Use nullable types (reference types) for properties if they should not be required - eg. int?.

Answer 2

You can always use formnovalidate on any input you don't want validated.
<input asp-for="Numero" formnovalidate="formnovalidate" class="form-control" />
This way there is no need to change your model. This is demonstrated at W3Schools