Re: My Ado.Net code is on a Public Holiday - C# Discussion Boards

21-Apr-09 23:20

Good Afternoon All

As you know in South Africa today is a Election day, i think my ado.net code went to the Elections tooo

i have this code in my DAL

public DataSet Lis_Databases(String DB)
        {

            Strcon = GetConnectionString(DB);


            con = new SqlConnection(Strcon);

            cmdselect = new SqlCommand();

            cmdselect.CommandText = "[dbo].[sp_ListDatabasesOfType_Booking]";

            cmdselect.CommandType = CommandType.StoredProcedure;

            cmdselect.Connection = con;

            da = new SqlDataAdapter();

            da.SelectCommand = cmdselect;

            DataSet ds = new DataSet();

            try
            {
                con.Open();

                da.Fill(ds);
            }
            catch (SqlException)
            {
                throw;
            }
            finally
            {
                if (con != null)
                {
                    con.Close();
                }
            }

            return ds;

        }

and i call this code in my BLL like this

public DataSet Lis_Databases(String DB)
        {
            DAL.DAL obj = new DAL.DAL();

            DataSet ds = new DataSet();

            try
            {
                ds = obj.Lis_Databases(DB);
            }
            catch (SqlException)
            {   
                throw;
            }
            finally
            {

                obj = null;
            }
            return ds;
           
        }

And call use it like this in my PL(Presention Layer)

private void List_Databases_Grid()
    {
        
            BLL.BLL obj = new BLL.BLL();
        
            DataSet ds = new DataSet();

        try
        {

            ds = obj.Lis_Databases(Convert.ToString(Session["ActiveDatabase"]));

            if (ds.Tables[0].Rows.Count > 0)
            {
                GridView_Database_list.DataSource = ds;

                GridView_Database_list.DataBind();
            }
            else
            {
                lblMessage.Text = "No Booking Database Avaiable,Create one";
                lblMessage.Visible = true;
                lblMessage.ForeColor = System.Drawing.Color.Red;
            }
        }
        catch (SqlException ex)
        {
            lblMessage.Visible = true;
            lblMessage.Text = "The List cannot be Binded, Please Contact ITS" + ex.Message;
            lblMessage.ForeColor = System.Drawing.Color.Red;
        }
        finally
        {
            obj = null;
        }

    }

when my code Comes to this line

if (ds.Tables[0].Rows.Count > 0)
           {

The evualuation, it passes and that mean records had been returned, now when it gets to this line

GridView_Database_list.DataSource = ds;

it says

Object reference not set to an instance of an object.

i have Initialized the Dataset everywhere as you can see above

what have i done wrong?

You can still Comment on my Error handling

Thank you

Vuyiswa Maseko

Vuyiswa Maseko,

Few companies that installed computers to reduce the employment of clerks have realized their expectations.... They now need more and more expensive clerks even though they call them "Developers" or "Programmers."

C#/VB.NET/ASP.NET/SQL7/2000/2005/2008
http://www.vuyiswamaseko.tiyaneProperties.co.za
vuyiswa@its.co.za
http://www.itsabacus.co.za/itsabacus/

Mbah Dhaim21-Apr-09 23:31

Mbah Dhaim

21-Apr-09 23:31

Vuyiswa Maseko wrote:
if (ds.Tables[0].Rows.Count > 0){

change that code to

if (ds.Tables.Count > 0 && ds.Tables[0].Rows.Count > 0){

hope it helps

dhaim
ing ngarso sung tulodho, ing madyo mangun karso, tut wuri handayani. "Ki Hajar Dewantoro"
in the front line gave a lead, in the middle line build goodwill, in the behind give power support

Vimalsoft(Pty) Ltd21-Apr-09 23:36

21-Apr-09 23:36

Good Day Mbah Dhaim

I have added such a Code to Check if there any rows and your code will check if there any tables in the dataset. but my Problem is here

GridView_Database_list.DataSource = ds;

i get

Object reference not set to an instance of an object.

Error

Thank you

Greg Chelstowski21-Apr-09 23:46

Greg Chelstowski

21-Apr-09 23:46

OK, which object is it failing on, the gridview or the dataset?
(I don't see how it could possibly fail on the dataset though).

Is the Gridview actually in your controls collection?
Do you add it dynamically (in which case, before you add it do you actually instantiate it properly?) or is it a control in your aspx page?
And if so, if you're using frames are you not trying to access a control that is in a different frame?
Or maybe the gridview is in a content holder of and you're trying to access it from a master page?

var question = (_2b || !(_2b));

Vimalsoft(Pty) Ltd22-Apr-09 0:00

22-Apr-09 0:00

Thank you Greg

The GridView was inside the UpdateProgress Control Roll eyes | :rolleyes:

My Mistake, Thank you.

Eddy Vluggen21-Apr-09 23:48

Eddy Vluggen

21-Apr-09 23:48

According to your logic, ds can't be empty. I guess that you already added a watch to verify that. Let's break the statement that the compiler is complaining about into some smaller parts;

GridView_Database_list.DataSource = ds;

Could it be that "GridView_Database_list" is null? Assigning a null-value to a variable isn't likely to cause errors, but assigning a value to something that is null, probably will.

--edit--
Read Greg's post - he's right in noticing that there may be some action triggered from the Grid itself once there is an assignment to the DataSource property Smile | :)

I are troll Smile | :)

Vimalsoft(Pty) Ltd21-Apr-09 23:58

21-Apr-09 23:58

Thanks for your Reply

The Gridview is Clean , there is nothing Assign to it.

Mbah Dhaim21-Apr-09 23:54

Mbah Dhaim

21-Apr-09 23:54

DataSet is referenced type, as you see in your BLL and PL in finally part you destroy your object (DAL and BLL) : finally {obj = null}, your dataset in PL will be lost reference too.
remove finally part of your code.

hope it helps

Vimalsoft(Pty) Ltd22-Apr-09 0:02

22-Apr-09 0:02

No No the Finally Part will only Destroy the object not the Dataset, the Dataset will be Teturned Correctly. Thank you for your help i have the problem

The GridView was inside the UpdateProgress Control Roll eyes | :rolleyes:

My Mistake, Thank you.

Mbah Dhaim22-Apr-09 0:10

Mbah Dhaim

22-Apr-09 0:10

Vuyiswa Maseko wrote:
My Mistake, Thank you.

you're welcome

this day i learn that referenced type will not destroy although its parent destroyed.
thank you very much.

Vimalsoft(Pty) Ltd22-Apr-09 0:13

How to add Ticks to an axis using nPlot and c#

22-Apr-09 0:13

You are Welcome Smile | :)

Mostrich21-Apr-09 22:59

Mostrich

21-Apr-09 22:59

Hi everybody,
i already plotted the content of a database with nplot.
The database contains only a few discrete values.
Now i am trying to add these exact ticks to my y-axis to increase readability.

Does anyone know how to add eight nonlinear spaces values as ticks to an y-axis using nplot and c#?

Muchas gracias

Identify the message end

yesu prakash21-Apr-09 22:59

yesu prakash

21-Apr-09 22:59

Hi,
How can i identify the message end in a socket communucation
eg:
when a client send byte[] to another client, the message went part by part. In the client side how can i identify the message is end. If the message is recived fully then i need to do next function.

Thankyou
YPKI

Re: Identify the message end

Rob Philpott21-Apr-09 23:13

Rob Philpott

21-Apr-09 23:13

A lot like strings, either send the size of the message prior to the message so the receiver knows how much to read, or use some sort of delimter to mark the end of the message.

Regards,
Rob Philpott.

[Message Deleted]

girishsatya21-Apr-09 22:47

girishsatya

21-Apr-09 22:47

[Message Deleted]

Rob Philpott21-Apr-09 22:49

Rob Philpott

21-Apr-09 22:49

Dude, I don't have a clue what you're on about.

Regards,
Rob Philpott.

yesu prakash21-Apr-09 23:04

yesu prakash

21-Apr-09 23:04

open project a class library
in class library---

public classlibrary
{
public void getfromdll(string name)
{
//display name
}
}

build -- u can get the dll from bin folder

in your application reffer the dll.

create an object of classlibrary..
call
getfromdll("Hi");

DaveyM6921-Apr-09 23:01

DaveyM69

21-Apr-09 23:01

Once you've added a reference to the dll in your project, all you need to do is use the correct namespace(s), class(es) [instanciating if necessary] then you'll have access to all the methods etc you wrote.

girishsatya wrote:
hWnd

What on earth has a hwnd got to do this?

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)
Why are you using VB6? Do you hate yourself? (Christian Graus)

Mycroft Holmes22-Apr-09 1:08

Mycroft Holmes

22-Apr-09 1:08

5 for deciphering what the bloody hell he was talking about.

Never underestimate the power of human stupidity
RAH