Problem with string array?

[ken76]

I have a problem with this code, because it gives me following error message
Object reference not set to an instance of an object when I use the line
values[countValues] = reader2.GetString("textinfo"); in the code below.

Can someone help me?

    public static string[] values;
    int countValues = 0;
    using (var connection = new MySqlConnection(connString))
                {
                    connection.Open();
                    string query = "select * from showvalues where idvalue = '" + idStatus + "'";
                    using (var command2 = new MySqlCommand(query, connection))
                    {
                        using (var reader2 = command2.ExecuteReader())
                        {
                            while (reader2.Read())
                            {
                         
                               listBoxMeasurement.Items.Add(reader2.GetString("textinfo"));
                              [B] values[countValues] = reader2.GetString("textinfo");[/B]
                               countValues++;
                            }
                           countValues = 0;
                           connection.Close();
                         }
                    }
                }

 

[jmcilhinney]

The very first thing to do when a NullReferenceException is thrown is check each reference on the offending line to see which is null. I would imagine that it's going to be values because there's nothing in that code that indicates that you're assigning an object to that variable, so it will not have a value.

 

[jmcilhinney]

Apart from that, it doesn't look like you know how many elements you need anyway, so you probably ought to be using a List<string> rather than an array. You'll have to actually create an object of that type either way though.

 

[cjard]

Please.. Install the VS extension "EF Core Power Tools", reverse engineer your database, throw all your code away and replace it with:

var db = new Yourcontext()
foreach(var x in db.ShowValues.Where(sv => sv.Id == idStatus)){
  listBoxMeasurement.Items.Add(x.TextInfo);
}