When do I set the value of a cascading drop down with an existing value?

Question

User-1423890915 posted

I have gotten cascading drop downs to work on my page.   The do fine when i am creating a new record.

 My problem is how to handle them when the user wants to edit an existing record.  I need to set drop down to show the existing value, but I can't figure out when to do that.  My first attempt was to do it in page_load - but at that point the first drop down has not yet been populated.

 What is the event that fires the population of the first drop down?

If i set the value of a cascading drop down in code, will that trigger the population of the dependent dropdown?

 Thanks,

Kirk

Answer 1

User-1087479560 posted

 Hi Kirk,

You need to achieve that in the method that fills the DDL by setting an item's isDefault property to true. For instance:

[System.Web.Services.WebMethod]
    [System.Web.Script.Services.ScriptMethod]
    public static AjaxControlToolkit.CascadingDropDownNameValue[]
        GetDropDownContentsPageMethod(string knownCategoryValues, string category, string contextKey)
    {
        AjaxControlToolkit.CascadingDropDownNameValue[] result =
            new AjaxControlToolkit.CascadingDropDownNameValue[10];
        for (int i = 0; i < 10; i++)
        {
            result[i] = new AjaxControlToolkit.CascadingDropDownNameValue();
            result[i].name = i.ToString();
            result[i].value = i.ToString();
            if (result[i].value == "???") // any criterion here
                result[i].isDefaultValue = true;
        }
        return result;
    }

Answer 2

User-1423890915 posted

Thank you!   That was exactly what I needed.

I declard some public variables in my service, and i set the value of the variables in Page_Load.

Then, as you suggest, In the loop that adds items to the list, I compare the value of each item against the value in the public variable.

Woiks like a charm! :)

Thanks again,

Kirk