When field validation is triggered, dropdownlists do not load into Asp.net core MVC

Question

When I start a registration screen, the system loads a ViewModel with the combobox loaded:

If I, for example, click the record button, the fields in my viewmodel are validated, only the page does not keep the combobox loaded.

How to solve this?

public class PessoaFisicaViewModel
{
        [DisplayName("Código")]
        public int Id { get; set; }

        [Required(ErrorMessage ="Campo obrigatório")]
        [DisplayName("Nome Completo")]
        public string NomeCompleto { get; set; }

        [DisplayName("Apelido")]
        public string Apelido { get; set; }

        [Required(ErrorMessage = "Campo obrigatório")]
        [DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:yyyy-MM-dd}")]
        [DataType(DataType.Date, ErrorMessage = "Data em formato inválido")]
        [DisplayName("Nascimento")]
        public DateTime? DataNascimento { get; set; }


        [DisplayName("Sexo")]
        public Sexo Sexo { get; set; }
        [DisplayName("Sexo")]
        public string SexoDescricao { get; set; }
        [DisplayName("Sexos")]
        public IEnumerable<SelectListItem> Sexos { get; set; }


        [DisplayName("Estado Civil")]
        public EstadoCivil EstadoCivil { get; set; }
        [DisplayName("Estado Civil")]
        public string EstadoCivilDescricao { get; set; }
        [DisplayName("Estados Civis")]
        public IEnumerable<SelectListItem> EstadosCivis { get; set; }

}

---

@model SistemaComercial.Application.ViewModels.Pessoa.PessoaViewModel
@{
    ViewData["Title"] = "PessoaFisica";
}

<div class="form-horizontal">
    <div class="form-group">
        <label asp-for="PessoaFisicaViewModel.NomeCompleto" class="col-md-2 control-label"></label>
        <div class="col-md-8">
            <input asp-for="PessoaFisicaViewModel.NomeCompleto" class="form-control" />
            <span asp-validation-for="PessoaFisicaViewModel.NomeCompleto" class="text-danger"></span>
        </div>
    </div>
    <div class="form-group">
        <label asp-for="PessoaFisicaViewModel.Apelido" class="col-md-2 control-label"></label>
        <div class="col-md-8">
            <input asp-for="PessoaFisicaViewModel.Apelido" class="form-control" />
            <span asp-validation-for="PessoaFisicaViewModel.Apelido" class="text-danger"></span>
        </div>
    </div>
    <div class="form-group">
        <label asp-for="PessoaFisicaViewModel.DataNascimento" class="col-md-2 control-label"></label>
        <div class="col-md-4">
            <input asp-for="PessoaFisicaViewModel.DataNascimento" class="form-control" />
            <span asp-validation-for="PessoaFisicaViewModel.DataNascimento" class="text-danger"></span>
        </div>
    </div>
    <div class="form-group">
        <label asp-for="PessoaFisicaViewModel.Sexo" class="col-md-2 control-label"></label>
        <div class="col-md-2">
            <select asp-for="PessoaFisicaViewModel.Sexo" asp-items="Model.PessoaFisicaViewModel.Sexos" class="form-control">
                <option value="">--Selecione--</option>
            </select>
            <span asp-validation-for="PessoaFisicaViewModel.Sexo" class="text-danger"></span>
        </div>
    </div>
    <div class="form-group">
        <label asp-for="PessoaFisicaViewModel.EstadoCivil" class="col-md-2 control-label"></label>
        <div class="col-md-3">
            <select asp-for="PessoaFisicaViewModel.EstadoCivil" asp-items="Model.PessoaFisicaViewModel.EstadosCivis" class="form-control">
                <option value="">--Selecione--</option>
            </select>
            <span asp-validation-for="PessoaFisicaViewModel.EstadoCivil" class="text-danger"></span>
        </div>
    </div>
</div>

[HttpPost]
        [Authorize(Policy = "CanWriteCustomerData")]
        [Route("pessoa-gerenciamento/cadastrar-novo")]
        [ValidateAntiForgeryToken]
        public IActionResult Create(PessoaViewModel pessoaViewModel)
        {
            if (!ModelState.IsValid) return View(pessoaViewModel);
            _pessoaAppService.Register(pessoaViewModel);

            if (IsValidOperation())
                ViewBag.Sucesso = "Pessoa Cadastrada!";

            return View(pessoaViewModel);
        }

Answer 1

Analyze your code well, I ended up noticing that the object passed is a PessoaFisicaViewModel, and View is signed as PessoaViewModel, apparently the PessoaViewModel does not have the properties of combobox listing (icollection), so when submiting, the conversion of PessoaFisicaViewModel for PessoaViewModel causes these properties to be lost.

Answer 2

In this case, I have the impression that you select the values in the Send Combos to SUBMIT, but since nothing has been saved, the validation is done but the object is returned again by _pessoaAppService.GetJoinById() and in this case, Combo values do not exist in the object returned by this service, and therefore do not return populated.

In my understanding, what you should do is, in the validation, return the validated object and not replace by the returned object by _pessoaAppService.GetJoinById().