How to assign a database value to a new object in C#?

Question

I’m creating an app like a bench to train C, but I ran into a situation. I have a database with the tables Accounts, Clients and Tiposconta. In the table Tiposconta there are registered the item "Savings" with ID "1" and the item "Chain" with ID "2". When I register a new account, I load the Account Types into a combobox to select the desired type. My question is as follows, how do I make so that when I register the account the ID of the account type is assigned to the new object "account" created?

Follow the code below:

Classe Conta:

public class Conta
{
    [Key]
    public int numero  { get; set; }

    public double saldo { get; protected set; }
    public TipoConta tipoConta { get; set; }
    public Cliente cliente { get;  set; }


    public Conta(Cliente idCliente)
    {
        this.cliente = idCliente;
        this.numero = numero;
        this.saldo = saldo;
        this.tipoConta = tipoConta;
    }

Class Typoconta

public class TipoConta
{
    public int id { get; set; }
    public string descricao { get; set; }


    public TipoConta()
    {
    }


}

Form Cadastrodecontas

public partial class CadastroDeContas : Form
{
    private CaixaEletronico aplicacaoPrincipal;   

    public CadastroDeContas(CaixaEletronico aplicacaoPrincipal)
    {
        this.aplicacaoPrincipal = aplicacaoPrincipal;
        InitializeComponent();
    }

    private void CadastroDeContas_Load(object sender, EventArgs e)
    {

        using (BancoContext contexto = new BancoContext())
        {
            comboTipoConta.DataSource = contexto.TiposConta.ToList();
            comboTipoConta.ValueMember = "id";
            comboTipoConta.DisplayMember = "descricao";
            comboTipoConta.Refresh();
            comboTipoConta.SelectedIndex = -1;

            //comboTipoConta.Items.Add("CORRENTE");
            //comboTipoConta.Items.Add("POUPANÇA");
        }
    }

    public void Limpar()
    {

        txtTitularNovaConta.Text = "";
        txtCpf.Text = "";
        comboTipoConta.Text = "";
    }


    public void btnCadastrar_Click(object sender, EventArgs e)
    {
        using (var contexto = new BancoContext())
        {
            var tiposConta = contexto.TiposConta.ToList();
        }

        if (txtTitularNovaConta.Text != "")
        {

            //converte os textos de entrada

            string nome = txtTitularNovaConta.Text;
            string cpf = txtCpf.Text;



           if (comboTipoConta.SelectedIndex >= 0)
            {
                //verifica se conta poupança ou corrente

                switch (comboTipoConta.SelectedIndex)
                {
                    case 0:

                        Cliente cliente = new Cliente();
                        Conta conta = new Conta();

                        cliente.Cpf = cpf;
                        cliente.Nome = nome;
                        conta.cliente = cliente;


                        this.aplicacaoPrincipal.AdicionaConta(cliente, conta);
                        using (var contexto = new BancoContext())
                        {
                            var tiposConta = contexto.TiposConta.ToList();
                            conta.tipoConta.id = Convert.ToInt32(comboTipoConta.ValueMember);

                            contexto.Clientes.Add(cliente);
                            contexto.Contas.Add(conta);


                            contexto.SaveChanges();
                            aplicacaoPrincipal.AdicionaConta(cliente, conta);
                        }
                        MessageBox.Show("Conta " + comboTipoConta.SelectedItem + " cadastrada com Sucesso");

                        Limpar();
                        break;

                    case 1:

                        Cliente cl = new Cliente();
                        Conta c = new Conta();

                        cl.Cpf = cpf;
                        cl.Nome = nome;
                        c.cliente = cl;
                        c.tipoConta.descricao = comboTipoConta.SelectedItem.ToString();
                        c.tipoConta.id = Convert.ToInt16(comboTipoConta.ValueMember);

                        this.aplicacaoPrincipal.AdicionaConta(cl, c);
                        using (var contexto = new BancoContext())
                        {
                            contexto.Clientes.Add(cl);
                            contexto.Contas.Add(c);
                            contexto.SaveChanges();
                            aplicacaoPrincipal.AdicionaConta(cl, c);
                        }
                        MessageBox.Show("Conta " + comboTipoConta.SelectedItem + " cadastrada com Sucesso");

                        Limpar();
                        break;


                }

Answer 1

Except for a lot of problems in your code...

you can remove that line:

comboTipoConta.ValueMember = "id";

and thus use the allocation:

conta.tipoConta = comboTipoConta.SelectedValue as TipoConta;

With Valuemember assigned ("id"), comboTipoConta.SelectedValue will return the id of the selected object in the combo. Without the assigned Valuemember, it will return the selected object itself.

---

Other excerpts you can remove as they are doing nothing:

    using (var contexto = new BancoContext())
    {
        var tiposConta = contexto.TiposConta.ToList();
    }

You do not need the list of account types at the time of recording. The entire list is already in the combo, and what you need will be selected.

---

 if (comboTipoConta.SelectedIndex >= 0)

You do not need to check for a selected item. When Fill in combo, the first item is selected, in which case it will never fall into a condition comboTipoConta.SelectedIndex < 0

---

switch (comboTipoConta.SelectedIndex)

You do not need to check the account type to enter. The insert of the two is exactly the same.

---

Ps.

Whereas there are not many options for account types, it is possible to use a enumerable for that reason:

public enum TiposConta
{
    ContaCorrente,
    ContaPoupanca,
    ContaSalario
}

Thus, there would be one less table in the database, and comparisons become simpler:

if (obj.TipoConta == TiposConta.ContaCorrente)
{
    //É uma conta Corrente
}