Cascading Combo Box

Harlem 98

I am trying to bind 2 combo box, being the value of the second dependent from de first.

All the solutions that i saw to this problem were by the use of Sql.Data (Datatable), which i cant use, due to the architecture of the application.

I can do it 2 ways, by c# or through ASP Object Data Source. I've trying this approach with any sucess. It is possible to do this?

...

if (!Page.IsPostBack)
{
 recursohumano rh = new RecursoHumano();
 rdpUnidade.DataValueField= "ID"
 rdpUnidade.DataTextField= "NomeUnidade"
 rdpUnidade.DataSource= new BLLUnidade().GetAll();
 rdpUnidade.DataBind();

 rdpInvestigador.DataValueField= "ID"
 rdpInvestigador.DataTextField= "Nome"
 rdpInvestigador.DataSource= new BLLRecursoHumano().GetAll();
 rdpInvestigador.DataBind();
 rdpInvestigador.Items.Insert(0, new RadComboBoxItem("", ""));

 //rdp investigador should depend on rdpUnidade

 private void rdpUnidade_SelectedIndexChanged(object sender, EventArgs e)
 {
 recursohumano rh = new RecursoHumano();

 var InvUnidade = from recursohumano in rh.recursohumano where recursohumano.id == Convert.ToInt32(rdpUnidade.SelectedValue) select recursohumano;
 rdpInvestigador.DataValueField= "ID";
 rdpInvestigador.DataTextField= "Nome";
 rdpInvestigador.DataSource = new BLLRecursoHumano().GetAll()
 }
...

6 Replies

Know the answer? Post it — somebody with the same question will find it here.

Sachin Singh4y ago
Accepted answer
if your GetAll() method returns a List and the list has multiple recursohumano.id, then the below code must return all the matching rows, otherwise, you need to look at the sql for GetAll() and what it returns, whether it includes the Id or not, also the selected value is giving you the id or not.

RecHumano.GetAll().where(x=>x.id==id).ToList();
Harlem 984y ago
Perfect! Thank you for the help!
Harlem 984y ago
@Sachin Singh

It works, but it's my fault that i forgot to mention a detail, the first comboBox selected value could match several values of the second ComboBox (rdpInvestigador), right now just evaluates the values, returning only 1 value in the second ComboBox.

So i believe the expression should evaluate bool, i've tried to do that but i still couldn't. Do you know how to do it (or another approach)?
Srinivasan Ramamoorthi4y ago
You have to pass the selected value from first combo box and filter the dataset binded to second combo box.
Rijwan Ansari4y ago
Hi

You can do filter in your query
private void rdpUnidade_SelectedIndexChanged(object sender, EventArgs e)
{
var recursohumanoId = Convert.ToInt32(rdpUnidade.SelectedValue);
recursohumano rh = new RecursoHumano();
rdpInvestigador.DataValueField= "ID";
rdpInvestigador.DataTextField= "Nome";
rdpInvestigador.DataSource = new BLLRecursoHumano().GetAll().where(x=>x.id = recursohumanoId).ToList();
}
Sachin Singh4y ago
your code is correct and should work. However you are not utilizing the rdpUnidade.SelectedValue in your code.
private void rdpUnidade_SelectedIndexChanged(object sender, EventArgs e)
{
var id=Convert.ToInt32(rdpUnidade.SelectedValue);
var RecHumano=new BLLRecursoHumano();
var res=RecHumano.GetAll().where(x=>x.id==id).ToList();

rdpInvestigador.DataValueField= "ID";
rdpInvestigador.DataTextField= "Nome";
rdpInvestigador.DataSource = res;
rdpInvestigador.DataBind();
}