Gridview row duplication C#

Question

1.00/5 (1 vote)

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Hello,

I have a webpage that allow the student to register courses and I want to display an error message if the student choose a course that has been taken before and already in the gridview.

Everything in the code is working fine,but when I use this loop

for (int i = 0; i < GridView1.Rows.Count;i++)

the code check the firt row only.

How can I make the for loop go through the all rows of gridview

What I have tried:

C#

protected void Button1_Click(object sender, EventArgs e)
        {

            for (int i = 0; i < GridView1.Rows.Count;i++)
            {

             if (GridView1.Rows[i].Cells[4].Text == DropDownList2.SelectedValue.ToString())
                {

                    //display error message.
                }
                else
                {
                    string stid = Label1.Text;
                    string coursecode = DropDownList2.SelectedValue.ToString();
                    string docid = lblDocID.Text;
                    string semester = lblSemester.Text;
                    string sessiondays = lblSessionDays.Text;
                    string days = lblDays.Text;
                    string timing = lblTiming.Text;
                    string startid = lblStartTime.Text;
                    string endtime = lblEndTime.Text;
                    string roomid = lblRoomID.Text;


                    SqlConnection ConnString = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
              String query = "insert into Registration values (@St_ID, @Semester, @CourseCode, @Doc_ID, @SessionDays, @Days, @Timing, @StartTime, @EndTime, @RoomID)";
                    SqlCommand cmd = new SqlCommand(query);

                    cmd.Connection = ConnString;
                    cmd.Parameters.AddWithValue("@St_ID", stid);
                    cmd.Parameters.AddWithValue("@Semester", semester);
                    cmd.Parameters.AddWithValue("@CourseCode", coursecode);
                    cmd.Parameters.AddWithValue("@Doc_ID", docid);
                    cmd.Parameters.AddWithValue("@SessionDays", sessiondays);
                    cmd.Parameters.AddWithValue("@Days", days);
                    cmd.Parameters.AddWithValue("@Timing", timing);
                    cmd.Parameters.AddWithValue("@StartTime", startid);
                    cmd.Parameters.AddWithValue("@EndTime", endtime);
                    cmd.Parameters.AddWithValue("@RoomID", roomid);
                    ConnString.Open();
                    cmd.ExecuteNonQuery();
                    ConnString.Close();

                    Response.Redirect("~/StudentAddDropCourse.aspx");

                }
            }
     }

Posted 20-Apr-17 12:47pm

R.M49

Updated 21-Apr-17 6:47am

v3

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Comments

Angelo L 20-Apr-17 19:13pm

Using the debugger, have you verified the strings you are comparing in the if statement, GridView1.Rows[i].Cells[4].Text and DropDownList2.SelectedValue.ToString()?

R.M49 20-Apr-17 19:17pm

yes, the problem is that the for loop checks only the first row, it doesn't go through the all rows.

Angelo L 20-Apr-17 20:25pm

It looks to me like your code is adding data every time the comparison fails inside the loop, but since you don't break the loop you continue to iterate through. For the if statement after you display the error message you should break to exit the for loop. You shouldn't do the else statement unless you've looked at all of the rows already, meaning you iterated through and didn't go into the if statement and break. So change the else to something like 'else if (i == GridView1.Rows.Count - 1)'.

R.M49 21-Apr-17 4:19am

wooow, it is working now, can you please write it as a soultion so I can accept it.

Angelo L 21-Apr-17 12:48pm

Glad to have helped.

2 solutions

Solution 1

You may find it some lengthy solution and have room for refactoring to but you can try below solution -

protected void Button1_Click(object sender, EventArgs e)
{
    var dataSource = GridView1.DataSource as DataTable;

    //Get all cources
    List<string> cources = new List<string>();
    foreach (DataRow row in dataSource.Rows)
    {
        //put your column details here
        cources.Add(row.ItemArray[1].ToString());
    }

    //Check if course already selected and avail in grid
    string SelectedCource = cources.Distinct().FirstOrDefault(m => m.Equals("<USERSELECTEDCOURCE>"));

    if(!String.IsNullOrEmpty(SelectedCource))
    {
        //error
    }
    else
    {
        //whatever you want to do to new selected cource
    }
}

Posted 20-Apr-17 14:15pm

User 4180254

Updated 20-Apr-17 14:17pm

v2

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Angelo L · Accepted Answer · 2017-04-21T06:47:00