How to insert values that have "," as decimal separator?

Question

Hello, I am making a product registration using . Net Core 3.1 and I have the following problem: In the product register there is a field to insert the value of the product, however when inserting a value with a comma, 300,50 for example, when exiting the input, the following message is returned : The field Price must be a number.. What can I do to insert values with "," ?

Code:

Product Class - Preco field

    [Required(ErrorMessage = "O campo <b>Preço</b> deve ser preenchido!")]
    [Display(Name = "Preço")]
    [DataType(DataType.Currency)]       
    public decimal Preco { get; set; }

In the Product class I make a select * from product id_Produto = @id_Produto and the attributes are fed as follows:

Produto produto = new Produto()
{
    ProdutoId = Convert.ToInt32(rdr["id_Produto"]),
    Descricao = rdr["descricao"].ToString(),
->  Preco = Convert.ToDecimal(rdr["preco"]),
    Status = rdr["status"].ToString(),
    Id_Categoria = Convert.ToInt32(rdr["id_Categoria"])

};

In the Edit.cshtml is like this:

<div class="form-group">
    <label asp-for="Preco" class="control-label"></label>
    <input asp-for="Preco" class="form-control"/>
    <span asp-validation-for="Preco" class="text-danger"></span>
</div>

Answer 1

One way to solve your problem is to create a Viewmodel and change the attribute to string by converting to the Product class in the controller, so you can validate your field without touching your Model directly.

Create the Viewmodel class and change your .cshtml to receive it:

public class ProdutoViewModel
{
    public int ProdutoId { get; set; }
    public string Descricao { get; set; }
    public string Preco { get; set; }
    public string Status { get; set; }
    public int Id_Categoria { get; set; }
}

And in Controller, make the following changes:

[HttpPost]
public async Task<IActionResult> Edit(ProdutoViewModel produtoViewModel)
{
    // Caso não seja um número válido, será retornado 0
    decimal.TryParse(produtoViewModel.Preco.Replace(".", string.Empty).Replace(",","."), out decimal preco);

    Produto produto = new Produto()
    {
        ProdutoId = produtoViewModel.ProdutoId,
        Descricao = produtoViewModel.Descricao,
        Preco =  preco,
        Status = produtoViewModel.Status,
        Id_Categoria = produtoViewModel.Id_Categoria 
    };

    // Sua lógica para gravar no banco

    return View(produtoViewModel);
}

Note that we replace the point with empty, and the comma per point, so when you receive the number "300.50" it will be transformed into "300.50", being a valid number.

We also do the Tryparse, to ensure that an Exception is not fired if it is not a number, so it returns the value 0.

Don’t forget to validate in HTML as well, to ensure data consistency.