Datareader opens and gives error by not closing

Question

I have a DataReader on my website to read the data that the bank brings. There when two people enter different computers, and even different browsers, opens a connection, but at the time I will read some data VS returns me an error

There is already an open Datareader associated with this Command that must be closed first

Would you have something that could change so that several people could access at the same time? Close Datareader?

 public static List<dMovimentoUser> listar_lancamentos(string conexao)
    {
        List<dMovimentoUser> carrinho = new List<dMovimentoUser>();
        Dados objDados = new Dados();
        SqlCommand command = new SqlCommand("usp_lancamentos_internos_listar", objDados.abreConexao());
        command.Parameters.AddWithValue("@conexao", conexao);
        command.CommandType = CommandType.StoredProcedure;
        SqlDataReader reader;
        reader = command.ExecuteReader();
        objDados.abreConexao();

        try
        {

            while (reader.Read())
            {
                dMovimentoUser ct = new dMovimentoUser();
                ct.codigo = reader["código"].ToString();
                ct.descricao = reader["produto"].ToString();
                ct.data = reader["data"].ToString();
                ct.hora = reader["hora"].ToString();
                ct.operacao = reader["operacao"].ToString();
                ct.qtd = float.Parse(reader["quantidade"].ToString());
                ct.historico = reader["historico"].ToString();
                carrinho.Add(ct);
            }
            return carrinho;
        }
        catch (Exception ex)
        {
            throw new Exception("Erro encontrado: " + ex.Message);
        }
        finally
        {
            reader.Close();
            objDados.fechaConexao();
        }
    }

Answer 1

This code has some problems.

public static List<dMovimentoUser> listar_lancamentos(string conexao) {
    var carrinho = new List<dMovimentoUser>();
    varobjDados = new Dados();
    //temo que esse abreConexao deve estar causando problema também
    using var command = new SqlCommand("usp_lancamentos_internos_listar", objDados.abreConexao();
    command.Parameters.AddWithValue("@conexao", conexao);
    command.CommandType = CommandType.StoredProcedure;
    using var reader = command.ExecuteReader(); //o using garante o fechamento
    //esse abreConexao não deve ter sido escrito do jeito correto também.
    objDados.abreConexao(); //de novo? isso está muito errado
    //já que não está fazendo nada útil com a exceção, é melhor não tratá-la aqui
    //se vai relançar a exceção sem resolver nada, não capture, principalmente Exception
    while (reader.Read()) {
        var ct = new dMovimentoUser();
        ct.codigo = reader["código"].ToString(); //acho que isso pode ser simplificado
        ct.descricao = reader["produto"].ToString();
        ct.data = reader["data"].ToString();
        ct.hora = reader["hora"].ToString();
        ct.operacao = reader["operacao"].ToString();
        ct.qtd = float.Parse(reader["quantidade"].ToString());
        ct.historico = reader["historico"].ToString();
        carrinho.Add(ct);
    }
    return carrinho;
}

I put in the Github for future reference.

Read other questions to better understand how using and the right way to manage resources "that need to be closed":

• Method to execute when destroying class instance
• I should always use Dispose?
• It is correct to use a block using within another block using?
• Nested dispose is necessary?
• Microsoft documentation.

If you still don’t understand I suggest asking more specific questions on the subject, reading a good book that teaches how to do it properly or looking for a good course that teaches you how to manage resources without risking keeping them open.

Answer 2

Good afternoon. After a long time, now I remembered to come here to show you the solution. Before I was creating a variable by pulling my connection string. And then I inserted it into Sqlconnection. To solve this problem of mine, I just put this my direct connection string into Sqlconnection. Thus remaining:

//O que dá erro
private static string stringConexao = @"Data Source=instacia;Initial Catalog=banco;User ID=sa;Password=******; MultipleActiveResultSets = true"
private static SqlConnection conexaoDecup = new SqlConnection(stringConexao);

//O que deu certo
private SqlConnection conexaoDecup = new SqlConnection(@"Data Source=instacia;Initial Catalog=banco;User ID=sa;Password=******; MultipleActiveResultSets = true");

That’s it. Thank you to those who tried to help me.