如何从ASP.Net中的Class获取Listbox.selected项

Question

I've done a method that returns values from my "Person" class. I'm now trying to get a specific value from that class by selected item in the list and then be able to use that value. This is my code and the error i get is "Cannot convert type 'System.Web.UI.WebControls.ListItem to". This is my Code:

       private Person aktuellPerson;

    protected void Page_Load(object sender, EventArgs e)
    {
        ListBoxPersoner.DataSource = Databasfunktioner.getPersoner();
        ListBoxPersoner.DataBind();
    }

    protected void ListBoxPersoner_SelectedIndexChanged(object sender, EventArgs e)
    {
      //Error below Cannot convert  type 'System.Web.UI.WebControls.ListItem to 'Testgrupp2.Person'
        aktuellPerson = (Person)ListBoxPersoner.SelectedItem;       
        TextBoxFornamn.Text = aktuellPerson.Fornamn;
    }

}

And this is myclass

public class Person
{
    public int PersonId { get; set; }
    public string Personnummer { get; set; }
    public string Fornamn { get; set; }
    public string Efternamn { get; set; }

    public override string ToString()
    {
        return Personnummer + " " + Fornamn + " " + Efternamn;
    }

}

Answer 1

The error is quite clear - SelectedItem returns a ListItem, not a Person. You should post the code for the ListBoxPersoner class but i suspect you have the person name in the ListItem Text property and the person ID in the Value property. If you don't have the person name in the ListItem you could use the Value to find the corresponding Person. Again this is just speculation since i don't know the implementation of ListBoxPersoner.

Answer 2

You cannot convert like this.

you need to create a Person Object and assign to some property.

protected void ListBoxPersoner_SelectedIndexChanged(object sender, EventArgs e)
    {
       Person p = new Person();
       p.Fornamn = ListBoxPersoner.SelectedItem.ToString();       
        TextBoxFornamn.Text = p.Fornamn;
    }

Answer 3

You have also to make some changes in your binding mecanism

 private Person aktuellPerson;

protected void Page_Load(object sender, EventArgs e)
{
    ListBoxPersoner.DataSource = Databasfunktioner.getPersoner();
    ListBoxPersoner.DataValueField="PersonID";
    ListBoxPersoner.DataTextField="Fornamn";
    ListBoxPersoner.DataBind();
}

    protected void ListBoxPersoner_SelectedIndexChanged(object sender, EventArgs )
   {
       var temItem= sender as DropDownList;  // if you are talking about DropDownList
        TextBoxFornamn.Text = temItem.SelectedItem.Text;
    }

}