Question

I have created an user control for cascading two dropdownlists “province” and “city”. But everytime when I run it, the error message said “An unhandled exception of type ‘System.StackOverflowException’ occurred”
Here is my user control code

public partial class cascadingdropdownlist : System.Web.UI.UserControl
{
    public string province_selectedvalue
    {

        set
        {
            string province_selectedvalue = value;
        }
        get
        {
            return city_selectedvalue;
        }
    }

    public string city_selectedvalue
    {
        set
        {
            string city_selectedvalue = value;
        }
        get
        {
            return city_selectedvalue;
        }
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        string a = province_selectedvalue;
        ............
    }

}

In the host page

<uc1:cascadingdropdownlist ID="province_city" runat="server" OnPreLoad="province_city_OnPreLoad"/>

The code behind is

protected void province_city_OnPreLoad(object sender, EventArgs e)
    {
        province_city.province_selectedvalue = myReader["Province/State"].ToString();
        province_city.city_selectedvalue = myReader["City"].ToString();
    }

The error happened in calling user control the province_selectedvalue.get method. why I don’t understand why? Anyone can help me, thanks very much

Answer 1

The problem is in your property:

public string city_selectedvalue 
{ 
    set 
    { 
        string city_selectedvalue = value; 
    } 

Calls the setter (or the getter!) on city_selectedvalue over and over again resulting in a stack overflow.

Replace your property with this

public string city_selectedvalue { get; set; }

I also thought you could do the same with province_selectedvalue but its getter refers to city_selectedvalue – is that correct?