How to load values in the combobox by the load event of form C #

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How to load values in the combobox by the load event of form C #

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#1 by (0 votes)
#2 by (0 votes)

1

I'm trying through this code:

private void frmAdicionarProdutos_Load(object sender, EventArgs e)
        {
             string serverName = "localhost";
             string port = "5432";
             string userName = "postgres";
             string password = "adm";
             string databaseName = "GE";
             NpgsqlConnection conn = null;
             string ConnString = null;

             ConnString = String.Format("Server={0};Port={1};User Id={2};Password={3};Database={4};",
                                           serverName, port, userName, password, databaseName);

            using (conn = new NpgsqlConnection(ConnString))
            {
                conn.Open();

                string cmdCarregar = String.Format("SELECT PRODUTOS.ID_PRODUTO, PRODUTOS.NOME, PRODUTOS.PRECO FROM PRODUTOS;");
                using (NpgsqlCommand cmd = new NpgsqlCommand(cmdCarregar, conn))
                {
                    NpgsqlDataReader dr = cmd.ExecuteReader();
                    DataTable dt = new DataTable();
                    dt.Load(dr);

                    cbProdutos.DisplayMember = "nome";
                    cbProdutos.ValueMember = "id_produto";
                    cbProdutos.DataSource = dt;
                    conn.Close();
                }     
            }
        }

At first I want to just test this way, then implement calling the class of the bank.

This code does not show anything in the ComboBox, I think I forgot something .. Well I would like to show: Product name + value of it (concatenated).

c#

asked by anonymous 23.10.2017 / 20:40

2 answers

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score 0 · Answer 1

I think it will work by adding the DataBind ()

cbProdutos.DataBind();

Make sure it works.

private void frmAdicionarProdutos_Load(object sender, EventArgs e)
    {
         string serverName = "localhost";
         string port = "5432";
         string userName = "postgres";
         string password = "adm";
         string databaseName = "GE";
         NpgsqlConnection conn = null;
         string ConnString = null;

         ConnString = String.Format("Server={0};Port={1};User Id={2};Password={3};Database={4};",
                                       serverName, port, userName, password, databaseName);

        using (conn = new NpgsqlConnection(ConnString))
        {
            conn.Open();

            string cmdCarregar = String.Format("SELECT PRODUTOS.ID_PRODUTO, PRODUTOS.NOME, PRODUTOS.PRECO FROM PRODUTOS;");
            using (NpgsqlCommand cmd = new NpgsqlCommand(cmdCarregar, conn))
            {
                NpgsqlDataReader dr = cmd.ExecuteReader();
                DataTable dt = new DataTable();
                dt.Load(dr);

                cbProdutos.DisplayMember = "nome";
                cbProdutos.ValueMember = "id_produto";
                cbProdutos.DataSource = dt;
                cbProdutos.DataBind();
                conn.Close();
            }     
        }
    }

score 0 · Answer 2

I can only see one cause for the problem: You did not associated the method frmAdicionarProdutos_Load with the event Form.Load

this.Load += new System.EventHandler(this.frmAdicionarProdutos_Load);

I tested your code here and the combo loaded it right.