I have a C#/WPF application with a tabbed interface that has been behaving strangely. After thinking originally my problems were related to the TabControl, I now believe that it's something different and I'm completely stuck. The following method is just supposed to pull some data out of the database and load a couple of WPF ComboBoxes. The strange thing is that the code reaches a certain point, specifically the end of the loop that loads cboState's Item collection, and then continues on. No code placed below that loop executes, no errors are thrown than I can find or see, and no breakpoints placed below that loop ever get reached. I'm completely perplexed.
private void loadNewProjectTab() {
dpDate.SelectedDate = DateTime.Now;
cboProjectType.Items.Add("Proposal");
cboProjectType.Items.Add("Pilot");
cboProjectType.SelectedIndex = -1;
string sql = "SELECT State FROM States ORDER BY ID";
OleDbCommand cmd = new OleDbCommand(sql, connection);
if(connection.State == ConnectionState.Closed) {
connection.Open();
}
OleDbDataReader reader = cmd.ExecuteReader();
while(reader.HasRows) {
reader.Read();
cboState.Items.Add(reader["State"].ToString().Trim());
} // <-- Nothing below here executes.
connection.Close();
}
while(reader.HasRows) {
reader.Read();
cboState.Items.Add(reader["State"].ToString().Trim());
}
reader.HasRows
will return true even after you've read all the rows and moved past the last one with reader.Read()
; at that point, you'll get an exception on reader["State"]
.
Since reader.Read()
returns a boolean to indicate whether there's a current row, you should skip calling reader.HasRows
entirely:
while(reader.Read()) {
cboState.Items.Add(reader["State"].ToString().Trim());
}
Um I think is wrong your loop it should be.
if (reader.HasRows)
{
while(reader.Read())
{
cboState.Items.Add(reader["State"].ToString().Trim());
}
}
Note that the bucle is with while(reader.Read())
This is your problem:
while(reader.HasRows) {
reader.Read();
cboState.Items.Add(reader["State"].ToString().Trim());
}
HasRows
indicates whether or not the reader retrieved anything; it doesn't change as you read through it (in other words, it's not analogous to an end-of-file indicator like you're using it). Instead, you should do this:
while(reader.Read()) {
cboState.Items.Add(reader["State"].ToString().Trim());
}
Reader
should be closed.
using(var reader = cmd.ExecuteReader())
{
if(reader.HasRows)
{
while(reader.Read())
{
cboState.Items.Add(reader["State"].ToString().Trim());
}
}
}
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