Handling Nulls

shahchi1 · June 22nd, 2004, 06:17 PM

I am using a DataReader object to return a single row from a database. I then use each of the fields within this row to populate controls on an .aspx page chances are there that few columns may contain a null value. Right now I have to check each and every database fields whether it contains a "NULL", Is there a better way to approach it?

melvik · June 22nd, 2004, 10:58 PM

Hi there:
Im sure this code will help u. save it in a ASPX file & run, u'll see the result.

Code:

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>

<Script Runat="Server">
  void Page_Load( Object s, EventArgs e )
  {
    SqlConnection myConnection;
    SqlCommand myCommand;
    myConnection = new SqlConnection( "Server=Localhost;uid=sa;Database=Pubs" );
    myCommand = new SqlCommand( "Select title, notes From Titles", myConnection );
    myConnection.Open();
    myRepeater.DataSource = myCommand.ExecuteReader();
    myRepeater.DataBind();
    myConnection.Close();
  }

  String fixNulls( String theString )
  {
    if ( theString == "" ) 
      return "[NULL]";
    else
      return theString;
  }
</Script>

<html>
<head><title>Titles</title></head>
<body>
 
<form Runat="Server">
 
<asp:Repeater
  id="myRepeater"
  Runat="Server">
  <HeaderTemplate>
  <table border=1 cellspacing=0 cellpadding=5>
  </HeaderTemplate>
  <ItemTemplate>
  <tr>
    <td><%# fixNulls( DataBinder.Eval( Container.DataItem, "title" ).ToString() ) %></td>
    <td><%# fixNulls( DataBinder.Eval( Container.DataItem, "notes" ).ToString() ) %></td>
  </tr>
  </ItemTemplate>
  <AlternatingItemTemplate>
  <tr bgcolor="lightyellow">
    <td><%# fixNulls( DataBinder.Eval( Container.DataItem, "title" ).ToString() ) %></td>
    <td><%# fixNulls( DataBinder.Eval( Container.DataItem, "notes" ).ToString() ) %></td>
  </tr>
  </AlternatingItemTemplate>
  <FooterTemplate>
  </table>
  </FooterTemplate>
</asp:Repeater>
</form>

</body>
</html>

Always:),
Hovik Melkomian.

shahchi1 · June 23rd, 2004, 11:43 AM

I ended up doing this (in my case i am populating the web controls), does anybody see any problem with it..Please Let me know.

Dim objDR As OleDbDataReader
objConn.Open()
objDR = objCmd.ExecuteReader(CommandBehavior.CloseConnecti on)

If objDR.Read Then
'Populating web controls
txtCompanyName.Text = "" & objDR("CompanyName")
txtContactName.Text = "" & objDR("ContactName")
txtContactTitle.Text = "" & objDR("ContactTitle")
txtAddress.Text = "" & objDR("Address")
txtCity.Text = "" & objDR("City")
txtRegion.Text = "" & objDR("Region")
txtPostalCode.Text = "" & objDR("PostalCode")
txtCountry.Text = "" & objDR("country")
txtPhone.Text = "" & objDR("phone")
txtFax.Text = "" & objDR("Fax")
txtHomePage.Text = "" & objDR("HomePage")
End If

melvik · June 23rd, 2004, 11:31 PM

Doesnt it work? Does it gives error?!
but I do guess u should convert to string.

Code:

  ...
   txtCompanyName.Text = "" & objDR("CompanyName").ToString()
   txtContactName.Text = "" & objDR("ContactName").ToString()
   txtContactTitle.Text = "" & objDR("ContactTitle").ToString()
  ...

Always:),
Hovik Melkomian.

shahchi1 · June 24th, 2004, 11:29 AM

thank you, Hovik