error while updating grid

[cmrhema]

hello,

I have used a GridView to edit and update a row.
I have produced the code below
However i get an error as below
I have underlined the place where i get the error

"NullRefere nce Exception was handled near the code"

 protected void GridView2_RowUpdating(object sender,GridViewUpdateEventArgs e)
    {
        String S1;
        SqlConnection MyCon = new SqlConnection("Server=HEMA\\SQLEXPRESS;Integrated Security=SSPI;database=demo");
        MyCon.Open();

        ImageButton b1 = new ImageButton();
        TextBox t1 = new TextBox();
        TextBox t2 = new TextBox();
        foreach (GridViewRow gv in GridView2.Rows)
        {
            b1 = (ImageButton)gv.FindControl("imagebutton1");
            t1 = (TextBox)gv.FindControl("TextBox1");
            t2 = (TextBox)gv.FindControl("TextBox2");
      
         [U]   if (b1.CommandName == "Update")[/U]
                
            {
                S1 = "update t1 set name='" + t2.Text + "' where id=" + t1.Text + "";
                SqlCommand UpdateCmd = new SqlCommand(S1, MyCon);
                Response.Write("updated");
                UpdateCmd.ExecuteNonQuery();
            }

        }

        MyCon.Close();
      
        
    }

What's the error and how to rectify it
thanks

[radcaesar]

Put a break point and Trace (Using F11), b1 should be null in ur code.

Where u have insert and Bind the Image button in ur grid. Is there any image button inside that ?

[cmrhema]

Put a break point and Trace (Using F11), b1 should be null in ur code.

Where u have insert and Bind the Image button in ur grid. Is there any image button inside that ?

yes radcaesar, i have indeed placed imagebutton instead of link or normal button. i inserted using the porperties. there i gave the corresponding name of the bmp.
As far as tracing is concerned i did trace it but i have already declared b1 as the image button1 in that case how am i supposed to get the error.

thanks for your reply

[Floydan]

hello,

I have used a GridView to edit and update a row.
I have produced the code below
However i get an error as below
I have underlined the place where i get the error

"NullRefere nce Exception was handled near the code"

 protected void GridView2_RowUpdating(object sender,GridViewUpdateEventArgs e)
{
String S1;
SqlConnection MyCon = new SqlConnection("Server=HEMA\\SQLEXPRESS;Integrated Security=SSPI;database=demo");
MyCon.Open();
 
ImageButton b1 = new ImageButton();
TextBox t1 = new TextBox();
TextBox t2 = new TextBox();
foreach (GridViewRow gv in GridView2.Rows)
{
b1 = (ImageButton)gv.FindControl("imagebutton1");
t1 = (TextBox)gv.FindControl("TextBox1");
t2 = (TextBox)gv.FindControl("TextBox2");
 
[u]if (b1.CommandName == "Update")[/u]
 
{
S1 = "update t1 set name='" + t2.Text + "' where id=" + t1.Text + "";
SqlCommand UpdateCmd = new SqlCommand(S1, MyCon);
Response.Write("updated");
UpdateCmd.ExecuteNonQuery();
}
 
}
 
MyCon.Close();
 
 
}

What's the error and how to rectify it
thanks

Hi,
Are you updating it one row at a time or several at a time?

If you are updating it several at a time then this might help. my only concern, since i havent tested this code myself is that .NET control ID's have to be unique, so each row will have diffrent id's for the controls.

protected void GridView2_RowUpdating(object sender, GridViewUpdateEventArgs e) {
string query = "update t1 set name='@Name' where id=@Id;";
string connStr = "Server=HEMA\\SQLEXPRESS;Integrated Security=SSPI;database=demo";
using (SqlConnection conn = new SqlConnection(connStr)) {
SqlCommand cmd = new SqlCommand(query, conn);
cmd.Connection.Open();
cmd.Parameters.Add("@Name", SqlDbType.NVarChar, 255);
cmd.Parameters.Add("@Id", SqlDbType.Int);
foreach (GridViewRow row in GridView2.Rows) {
if (row.RowState == DataControlRowState.Edit) {
	TextBox nameBox = row.FindControl("TextBox1");
	TextBox idBox = row.FindControl("TextBox2");
 
	int id = -1;
	Int32.TryParse(id.Text, out id);
	if(id > 0) {
	 cmd.Parameters["@Name"].Value = nameBox.Text.Replace("'", "''");
	 cmd.Parameters["@Id"].Value = id;
 
	 cmd.ExecuteNonQuery();
	}
}
}
cmd.Connection.Close();
cmd.Dispose();
}
}

If you are just updating it 1 row at a time then this might help:

protected void GridView2_RowUpdating(object sender, GridViewUpdateEventArgs e) {
 string query = "update t1 set [email="name='@Name'"]name='@Name'[/email] where [email="id=@Id"]id=@Id[/email];";
 string connStr = "Server=HEMA\\SQLEXPRESS;Integrated Security=SSPI;database=demo";
 using (SqlConnection conn = new SqlConnection(connStr)) {
  SqlCommand cmd = new SqlCommand(query, conn);
  cmd.Connection.Open();
  cmd.Parameters.Add("@Name", SqlDbType.NVarChar, 255);
  cmd.Parameters.Add("@Id", SqlDbType.Int);
  foreach (GridViewRow row in GridView2.Rows) {
   if (row.RowState == DataControlRowState.Edit) {
	TextBox nameBox = row.FindControl("TextBox1");
	TextBox idBox = row.FindControl("TextBox2");
 
	int id = -1;
	Int32.TryParse(id.Text, out id);
	if(id > 0) {
	 cmd.Parameters["@Name"].Value = nameBox.Text.Replace("'", "''");
	 cmd.Parameters["@Id"].Value = id;
 
	 cmd.ExecuteNonQuery();
	}
   }
  }
  cmd.Connection.Close();
  cmd.Dispose();
 }
}

[cmrhema]

Hi,
Are you updating it one row at a time or several at a time?

If you are updating it several at a time then this might help. my only concern, since i havent tested this code myself is that .NET control ID's have to be unique, so each row will have diffrent id's for the controls.

protected void GridView2_RowUpdating(object sender, GridViewUpdateEventArgs e) {
string query = "update t1 set name='@Name' where id=@Id;";
string connStr = "Server=HEMA\\SQLEXPRESS;Integrated Security=SSPI;database=demo";
using (SqlConnection conn = new SqlConnection(connStr)) {
SqlCommand cmd = new SqlCommand(query, conn);
cmd.Connection.Open();
cmd.Parameters.Add("@Name", SqlDbType.NVarChar, 255);
cmd.Parameters.Add("@Id", SqlDbType.Int);
foreach (GridViewRow row in GridView2.Rows) {
if (row.RowState == DataControlRowState.Edit) {
	TextBox nameBox = row.FindControl("TextBox1");
	TextBox idBox = row.FindControl("TextBox2");
 
	int id = -1;
	Int32.TryParse(id.Text, out id);
	if(id > 0) {
	 cmd.Parameters["@Name"].Value = nameBox.Text.Replace("'", "''");
	 cmd.Parameters["@Id"].Value = id;
 
	 cmd.ExecuteNonQuery();
	}
}
}
cmd.Connection.Close();
cmd.Dispose();
}
}

If you are just updating it 1 row at a time then this might help:

protected void GridView2_RowUpdating(object sender, GridViewUpdateEventArgs e) {
 string query = "update t1 set [email="name='@Name'"]name='@Name'[/email] where [email="id=@Id"]id=@Id[/email];";
 string connStr = "Server=HEMA\\SQLEXPRESS;Integrated Security=SSPI;database=demo";
 using (SqlConnection conn = new SqlConnection(connStr)) {
  SqlCommand cmd = new SqlCommand(query, conn);
  cmd.Connection.Open();
  cmd.Parameters.Add("@Name", SqlDbType.NVarChar, 255);
  cmd.Parameters.Add("@Id", SqlDbType.Int);
  foreach (GridViewRow row in GridView2.Rows) {
   if (row.RowState == DataControlRowState.Edit) {
	TextBox nameBox = row.FindControl("TextBox1");
	TextBox idBox = row.FindControl("TextBox2");
 
	int id = -1;
	Int32.TryParse(id.Text, out id);
	if(id > 0) {
	 cmd.Parameters["@Name"].Value = nameBox.Text.Replace("'", "''");
	 cmd.Parameters["@Id"].Value = id;
 
	 cmd.ExecuteNonQuery();
	}
   }
  }
  cmd.Connection.Close();
  cmd.Dispose();
 }
}

Thanks floydan for replying that to in such a precise manner.
I may update a single row or many rows at a time.
I tried your code
Unfortunately i cannot use
int id = -1;
Int32.TryParse( id.Text, out id);

because i am using an image button for edit update which does not have a text property. i tried to change to tostring but to no success.

now to the most funniest part because i missed the above lines what happens is only the alternate record gets updated.
i am now working on it

Anyway thank you very much indeed.

[Floydan]

Well as I said, it was just something i wrote from the top of my head without any real testing =)

Since i have no idea how your gridview looks alot of it are based on pure quessing =)