Question

How do I programmatically set the selectedValue of cascading dropdownlists in C#

Asked by: christiegroup

I have an ASP.NET 2.0 app that has multiple pages with 2 dropdownlists on.
ddl1 = CostCentre
ddl2 = Employee

Both ddl are bound to sqldatasources and ddl2 has a parameter which is bound to the value of ddl1. This all works fine.

What i want to do is when the user moves from one page to another the dropdownlists are set to the Costcentre and Employee that was selected on the previous page.

The costcentre ddl i have no problem with but its setting the value of the Employee ddl which relies on the costcentre being selected.

Session variable are set with the selected values of the ddl's.

i have tried this code but the employee ddl ends up empty with no value selected.

protected void Page_Load(object sender, EventArgs e)
    {
            if (Session["CC"] != null)
            {
                ddCCList.SelectedValue = (string)Session["CC"];                
                ddEmployeeList.DataBind();
                if (Session["EmpID"] != null)
                {
                    ddEmployeeList.SelectedValue = (string)Session["EmpID"];
                }
            }        
    }

i have also tried putting similar code in the ondatabound event of the dropdownlists but that doesn't work either.

Any help appreciated.

Anthony

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Asked On
2008-06-24 at 07:04:32ID23511012
Tags

ASP.NET 2.0 / C#

,

Internet Explorer 6/7

Topics

Programming for ASP.NET

,

Microsoft Visual C#.Net

Participating Experts
1
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Comments
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Answers

 

by: ydramuPosted on 2008-06-24 at 07:14:14ID: 21855937

Could you verify once your Session["CC"] value is not null.

 

by: ydramuPosted on 2008-06-24 at 07:18:19ID: 21855968

If it has value then try with this way.

ddCCList.Items.FindByText((string)Session["CC"]).Selected = true;

 

by: christiegroupPosted on 2008-06-24 at 08:05:40ID: 21856550

Hi vdramu,

i get "Object reference not set to an instance of an object. " if i use

ddCCList.Items.FindByText((string)Session["CC"]).Selected = true;

 

by: ydramuPosted on 2008-06-24 at 08:13:19ID: 21856646

Please try with this way.

Seems your Session value getting null.    

And try do the same null varification for the EmpID and then try that variable with Drop down list.

  if (Session["CC"] != null)
            {
 
                string selectValue= (string)Session["CC"];             
                ddCCList.Items.FindByText(selectValue).Selected = true;
                ............
                ............
             }

                                              
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by: christiegroupPosted on 2008-06-24 at 09:19:11ID: 21857409

Hi vdramu,

I still get the "Object reference not set to an instance of an object." but i have found a way to do it.

Putting the code in the databound event of the dropdownlist works fine. I tried this before but i had ddEmployeeList.DataBind(); in the ddCCList_DataBound event which causes problems. I have tried it again taking it out and it now works

Here is the code.

protected void ddCCList_DataBound(object sender, EventArgs e)
    {
        if (Session["CC"] != null)
        {
            ddCCList.SelectedValue = (string)Session["CC"];            
        }
    }
    protected void ddEmployeeList_DataBound(object sender, EventArgs e)
    {
        if (Session["EmpID"] != null)
        {
            ddEmployeeList.SelectedValue = (string)Session["EmpID"];
        }
    }  

Thanks for trying to help with this.

Anthony

20120131-EE-VQP-002

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