Bind ListBox with DataTable RSS

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  usamaalam

  Member

  389 Points

  148 Posts

  Bind ListBox with DataTable

  Mar 17, 2005 12:19 PM|LINK

  Hello everybody, I have a method in my business class and I send reference of a listbox to that method to fill it. Method first fills fetches the records in a DataTable and then binds the DataTable with ListBox. Here is the code.

  public void Fill(ref System.Web.UI.WebControls.ListBox thisList)
  {
       //  Object of Data Access Layer - Related Class
       DataAccessLayer.Group groupDAL = new DataAccessLayer.Group();
       groupDAL.GetAll();
  					
  
       int count = 0 ;
       DataTable dtTemporary  = new DataTable();
       dtTemporary.Clear();
       DataColumn dc1 = new DataColumn("ID",Type.GetType("System.Int32"));
       DataColumn dc2 = new DataColumn("Name",Type.GetType("System.String") );
       dtTemporary.Columns.Add(dc1);
       dtTemporary.Columns.Add(dc2);
       while ( groupDAL.Read() )
       {
  	count++;
  	DataRow rowgroup = dtTemporary.NewRow();
  	rowgroup["ID"] =  groupDAL.ID;
  	rowgroup["Name"] =  groupDAL.Name;
  	dtTemporary.Rows.Add(rowgroup);
        }
       groupDAL.Dispose();
       thisList.DataSource = dtTemporary;
       thisList.DataTextField = "Name";
       thisList.DataValueField = "ID";
  }

  I am getting the error messages, "Object reference not set to an instance of an object" on this line. thisList.DataSource = dtTemporary; Thanks.
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  ccalderon

  Contributor

  4732 Points

  955 Posts

  Re: Bind ListBox with DataTable

  Mar 17, 2005 03:18 PM|LINK

  and the error is that "thisList" is null I guess... when (event) and how are u passing "thisList" to the function?
  Christian Calderon
  Principal, Software Architec and Delivery
  http://www.eki-consulting.com
  http://www.linkedin.com/in/chriscalderon
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  usamaalam

  Member

  389 Points

  148 Posts

  Re: Bind ListBox with DataTable

  Mar 18, 2005 03:16 AM|LINK

  I am calling the method like this.

  groups.Fill(ref ListBox1);

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  shravan79

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  Re: Bind ListBox with DataTable

  Mar 18, 2005 04:24 AM|LINK

  Is ListBox1 an object on your page?? U cud infact send it directly without the ref keyword at all. U would still see what u are expecting to see happen to the ListBox1 control since ListBox1 control is available for anymodule in the code behind. Try that and see if it works. hth
  Shravan Addaypally MCP
  
  
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  ccalderon

  Contributor

  4732 Points

  955 Posts

  Re: Bind ListBox with DataTable

  Mar 18, 2005 01:36 PM|LINK

  on which event or from where are u calling

  groups.Fill(ref ListBox1);

  I'm asking because I think the issue is that ListBox1 is null at the time you are passing it. And you DO need to use the ref keword if the receiving method used a ref parameter ..., so that's good.
  Christian Calderon
  Principal, Software Architec and Delivery
  http://www.eki-consulting.com
  http://www.linkedin.com/in/chriscalderon
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  usamaalam

  Member

  389 Points

  148 Posts

  Re: Bind ListBox with DataTable

  Mar 19, 2005 03:05 AM|LINK

  I am calling the method on Page Load event.
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