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Asked: 2026-05-11T05:44:45+00:00

I have multiple drop down lists on a page. They all contain list of

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I have multiple drop down lists on a page. They all contain list of countries. So in the background I am getting countries from database and caching them. I would like to populate those drop down lists from another thread. I am also using AJAX controls so I wanted that it all happens at the same time. And also after a user selects a country I want that towns from that country show to the user, and I want that getting towns happens also in another thread so that user can fill other controls while the list is not yet loaded.
I have read somewhere that I should give Page as a parameter to that thread and then find that drop down lists and populate them. But that is not working.

Here is a function that is called when another thread starts:

protected void GetCountries(object o) {     if (Session['Countries'] == null)     {         Session['Countries'] = CountryRepository.Instance.GetAll();     }     if (o is Page)     {         Page p = (Page)o;         DropDownList ddl = (DropDownList)p.FindControl('ddlCountry');         ddl.DataSource = Session['Countries'] as List<Country>;         ddl.DataTextField = 'Name';         ddl.DataValueField = 'Id';         ddl.DataBind();     } }

Anyone sees a possible problem? Or perhaps my whole concept is wrong? Does anyone have an idea how to solve this problem?

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1 Answer

  1. Take a look at the CascadingDropDown Extender from the ASP.NET AJAX Control Toolkit. It uses web services to populate the dropdowns, so it can operate asynchronously (which I believe is what you’re after).

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