asp.net-mvcasp.net-coreinputargumentnullexception
Value cannot be null. Parameter name DropdownList in ASP. NET CORE
I have a problem in mi code, when show the error message appears the message of the title
This is the code of my form Register
<div class="form-group col-md-6">
@if (!Model.MODEL_PACIENTE.PAC_ID.Equals(0))
{
<label>Comuna:</label>
@Html.DropDownList("MODEL_PACIENTE.PAC_COMUNA", new SelectList(Model.MODEL_PACIENTE.Comuna_Lista, "Text", "Text"),
new { @class = "form-control" })
}
else
{
<label>Comuna:</label>
@Html.DropDownList("MODEL_PACIENTE.PAC_COMUNA", new SelectList(Model.MODEL_PACIENTE.Comuna_Lista, "Text", "Text"),
"ESCOGA UNA COMUNA", new { @class = "form-control" }) // HERE IS THE ERROR WHEN MY DNI IS REGISTER IN THE BD }
<span asp-validation-for="MODEL_PACIENTE.PAC_COMUNA" class="text-danger"></span>
</div>
Code of my class GetOdontologo
public List<SelectListItem> GetOdontologo(ApplicationDbContext context)
{
List<SelectListItem> selectListItems = null;
try
{
selectListItems = new List<SelectListItem>();
context.TBL_ODONTOLOGO.ToList().ForEach(item =>
{
selectListItems.Add(new SelectListItem
{
Value = item.ODONT_ID.ToString(),
// Text = item.ODONT_CODIGO
Text = item.ODONT_CODIGO + '-' + item.ODONT_APELLIDO + ' ' + item.ODONT_NOMBRE
});
});
}
catch (Exception ex)
{
Console.WriteLine($"Error: '{ex}'");
}
return selectListItems;
}
This is the class GetComuna
public List<SelectListItem> GetComuna(ApplicationDbContext context)
{
List<SelectListItem> selectListItems = null;
try
{
selectListItems = new List<SelectListItem>();
context.TBL_PROVINCIA.ToList().ForEach(item =>
{
selectListItems.Add(new SelectListItem
{
Value = item.PROV_ID.ToString(),
Text = item.PROV_NOMBRE
});
});
}
catch (Exception ex)
{
Console.WriteLine($"Error: '{ex}'");
}
return selectListItems;
}
And this the code of my method "onget"
public void OnGet(int idActPac)
{
_DataPac2 = null;
if(idActPac.Equals(0))
{
_DataPac2 = null;
}
if (_dataInput != null || _DataPac1 != null || _DataPac2 != null)
{
if (_dataInput != null)
{
MODEL_PACIENTE = _dataInput;
MODEL_PACIENTE.AvatarImage = null;
}
else
{
if (_DataPac1 != null || _DataPac2 != null)
{
if (_DataPac2 != null)
_DataPac1 = _DataPac2;
MODEL_PACIENTE = new PACIENTE
{
PAC_ID = _DataPac1.PAC_ID,
PAC_NOMBRE = _DataPac1.PAC_NOMBRE,
PAC_APELLIDO = _DataPac1.PAC_APELLIDO,
PAC_CODIGO = _DataPac1.PAC_CODIGO,
PAC_EDAD = _DataPac1.PAC_EDAD,
PAC_COD_ODONT = _DataPac1.PAC_COD_ODONT,
PAC_COMUNA = _DataPac1.PAC_COMUNA,
PAC_CORREO = _DataPac1.PAC_CORREO,
PAC_DIRECCION = _DataPac1.PAC_DIRECCION,
PAC_OBSERVACIONES = _DataPac1.PAC_OBSERVACIONES,
PAC_OTRAS_COMUNAS = _DataPac1.PAC_OTRAS_COMUNAS,
PAC_CONVENIO = _DataPac1.PAC_CONVENIO,
PAC_PREVISIONES = _DataPac1.PAC_PREVISIONES,
PAC_REPRESENTANTE = _DataPac1.PAC_REPRESENTANTE,
PAC_RUT = _DataPac1.PAC_RUT,
PAC_SEXO = _DataPac1.PAC_SEXO,
PAC_TELEFONO = _DataPac1.PAC_TELEFONO,
PAC_FECHA_NAC = _DataPac1.PAC_FECHA_NAC,
PAC_FEC_ACT = _DataPac1.PAC_FEC_ACT,
PAC_FEC_REG = _DataPac1.PAC_FEC_REG,
PAC_IMAGEN = _DataPac1.PAC_IMAGEN,
//AL USAR EL METODO ACTUALIZAR AL CARGAR LOS DATOS EN LOS INPUT NO OLVIDAR QUE SE DEBE CARGAR
//NUEVAMENTE LOS DropDownList LLAMANDOLO NUEVAMENTE AL FINAL COMO SE VE EN EL CODIGO A CONTINUACION
Genero_Lista = _lPacienteGen.GetGenero(_context),
Comuna_Lista = _lComuna.GetComuna(_context),
Odontologo_Lista = _lOdontologo.GetOdontologo(_context)
};
if (_dataInput != null)
{
MODEL_PACIENTE.ErrorMessage = _dataInput.ErrorMessage;
}
}
}
}
else
{
var Cod_Pac = 0;
String TempCodPac = null;
var Ultimo_Paciente = (from t in _context.TBL_PACIENTE
orderby t.PAC_CODIGO
select t).LastOrDefault();
if (Ultimo_Paciente != null)
{
Cod_Pac = (Ultimo_Paciente.PAC_CODIGO != null) ?
Convert.ToInt32(Ultimo_Paciente.PAC_CODIGO) + 1 :
1;
if (Cod_Pac < 10)
{
TempCodPac = String.Concat("0000", Convert.ToString(Cod_Pac));
}
else if (Cod_Pac >= 10 && Cod_Pac <= 11)
{
TempCodPac = String.Concat("000", Convert.ToString(Cod_Pac));
}
else if (Cod_Pac > 10 && Cod_Pac < 100)
{
TempCodPac = String.Concat("000", Convert.ToString(Cod_Pac));
}
else if (Cod_Pac >= 100 && Cod_Pac <=101)
{
TempCodPac = String.Concat("00", Convert.ToString(Cod_Pac));
}
else if (Cod_Pac > 100 && Cod_Pac < 1000)
{
TempCodPac = String.Concat("00", Convert.ToString(Cod_Pac));
}
else if (Cod_Pac >= 1000 && Cod_Pac <= 1001)
{
TempCodPac = String.Concat("0", Convert.ToString(Cod_Pac));
}
else if (Cod_Pac > 1000 && Cod_Pac <= 9999)
{
TempCodPac = String.Concat("0", Convert.ToString(Cod_Pac));
}
else if (Cod_Pac > 9999 && Cod_Pac < 99999)
{
TempCodPac = String.Concat("", Convert.ToString(Cod_Pac));
}
}
MODEL_PACIENTE = new PACIENTE
{
PAC_CODIGO = TempCodPac,
Genero_Lista = _lPacienteGen.GetGenero(_context),
Comuna_Lista = _lComuna.GetComuna(_context),
Odontologo_Lista = _lOdontologo.GetOdontologo(_context),
PAC_COD_ODONT = "00000"
};
}
_DataPac2 = _DataPac1;
_DataPac1 = null;
}
The code of my method Save_Patient
private async Task<bool> Guardar_Paciente_Async()
{
_dataInput = MODEL_PACIENTE;
var valor = false;
if (ModelState.IsValid)
{
var PacLista = _context.TBL_PACIENTE.Where(u => u.PAC_RUT.Equals(MODEL_PACIENTE.PAC_RUT)).ToList();
if (PacLista.Count.Equals(0))
{
var strategy = _context.Database.CreateExecutionStrategy();
await strategy.ExecuteAsync(async () =>
{
using (var transaction = _context.Database.BeginTransaction())
{
try
{
var imagenByte = await _lCargarImagen.ByteAvatarImageAsync(MODEL_PACIENTE.AvatarImage, _environment, "images/user_icon.png");
string TmpCodPac = _dataInput.PAC_COD_ODONT;
String vfCodPac = TmpCodPac.Substring(0, 4);
var Nuevo_Paciente = new MODELO_PACIENTE
{
PAC_CODIGO = _dataInput.PAC_CODIGO,
PAC_NOMBRE = _dataInput.PAC_NOMBRE.ToUpper(),
PAC_APELLIDO = _dataInput.PAC_APELLIDO.ToUpper(),
PAC_SEXO = _dataInput.PAC_SEXO,
PAC_RUT = _dataInput.PAC_RUT,
PAC_FECHA_NAC = _dataInput.PAC_FECHA_NAC,
PAC_EDAD = _dataInput.PAC_EDAD,
PAC_REPRESENTANTE = _dataInput.PAC_REPRESENTANTE?.ToUpper(),
PAC_DIRECCION = _dataInput.PAC_DIRECCION?.ToUpper(),
PAC_COMUNA = _dataInput.PAC_COMUNA?.ToUpper(),
PAC_OTRAS_COMUNAS = _dataInput.PAC_OTRAS_COMUNAS?.ToUpper(),
PAC_TELEFONO = _dataInput.PAC_TELEFONO,
PAC_CORREO = _dataInput.PAC_CORREO,
PAC_CONVENIO = _dataInput.PAC_CONVENIO?.ToUpper(),
PAC_PREVISIONES = _dataInput.PAC_PREVISIONES?.ToUpper(),
PAC_OBSERVACIONES = _dataInput.PAC_OBSERVACIONES?.ToUpper(),
PAC_COD_ODONT = vfCodPac,
PAC_IMAGEN = imagenByte,
PAC_FEC_REG = DateTime.Now,
PAC_FEC_ACT = DateTime.Now
};
await _context.AddAsync(Nuevo_Paciente);
_context.SaveChanges();
transaction.Commit();
_dataInput = null;
valor = true;
}
catch (Exception ex)
{
_dataInput.ErrorMessage = ex.Message;
transaction.Rollback();
valor = false;
}
}
});
}
else
{
_dataInput.ErrorMessage = $"El RUT {MODEL_PACIENTE.PAC_RUT} ya se encuentra Registrado";
// It should show this error in the respective "input", but the error message you see below in the image appears
}
}
else
{
foreach (var modelState in ModelState.Values)
{
foreach (var error in modelState.Errors)
{
_dataInput.ErrorMessage += error.ErrorMessage;
}
}
valor = false;
}
return valor;
}
If I debug, when I start it loads the 2 records from the dentist table, but when I put the existing ID at the time of appearing the error message appears what is seen in the image and when trying to load the list again it comes out null
After checking the ID error, the "Odontologia Lista" method returns null and the title error appears
where is the problem ?, I appreciate your help or guide to solve this problem.
Solution
You can try to check the following code:
MODEL_PACIENTE = new PACIENTE
{
PAC_CODIGO = TempCodPac,
//Genero_Lista = _lPacienteGen.GetGenero(_context),
Comuna_Lista = _lComuna.GetComuna(_context),
//Odontologo_Lista = _lOdontologo.GetOdontologo(_context),
PAC_COD_ODONT = "00000"
};
Odontologo_Lista = _lOdontologo.GetOdontologo(_context), is commented.If _dataInput == null && _DataPac1 == null && _DataPac2 == null,the Odontologo_Lista will not be set,and you will get the error Value cannot be null.