This is a migrated thread and some comments may be shown as answers.

Filter RadComboBox from another combobox

6 Answers 639 Views

ComboBox

This is a migrated thread and some comments may be shown as answers.

6 Answers, 1 is accepted

answered on 13 Jul 2020, 02:15 PM

Hi Ciupaz,

Here is an example for creating Cascading ComboBoxes using CheckBoxes:

Markup - ComboBoxes

<telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
</telerik:RadAjaxManager>
<telerik:RadComboBox ID="RadComboBox1" runat="server" AutoPostBack="true" OnLoad="RadComboBox1_Load" OnSelectedIndexChanged="RadComboBox1_SelectedIndexChanged" EmptyMessage="Select a Continent">
</telerik:RadComboBox>
<telerik:RadComboBox ID="RadComboBox2" runat="server" AutoPostBack="true" EmptyMessage="Select a Country" CheckBoxes="true" OnItemChecked="RadComboBox2_ItemChecked">
</telerik:RadComboBox>
<telerik:RadComboBox ID="RadComboBox3" runat="server" AutoPostBack="true" EmptyMessage="Select a City">
</telerik:RadComboBox>

C# - code behind

protected void RadComboBox1_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        var combo = (sender as RadComboBox);
        combo.DataSource = Enumerable.Range(1, 3).Select(x => new { value = x, text = "Continent " + x });
        combo.DataTextField = "text";
        combo.DataValueField = "value";
        combo.DataBind();
    }
}

protected void RadComboBox1_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
{
    RadComboBox2.ClearSelection();
    RadComboBox3.Items.Clear();
    RadComboBox3.ClearSelection();
    RadComboBox2.DataSource = Enumerable.Range(1, 3).Select(x => new { value = x, text = "Continent " + e.Value.ToString() + " Country " + x }); ;
    RadComboBox2.DataTextField = "text";
    RadComboBox2.DataValueField = "value";
    RadComboBox2.DataBind();
}

private List<dynamic> Cities()
{
    var cities = new List<dynamic>();

    cities.Add(new { value = 1, countrtyId = 1, text = "Country 1, City 1" });
    cities.Add(new { value = 2, countrtyId = 1, text = "Country 1, City 2" });
    cities.Add(new { value = 3, countrtyId = 1, text = "Country 1, City 3" });
    cities.Add(new { value = 4, countrtyId = 2, text = "Country 2, City 1" });
    cities.Add(new { value = 5, countrtyId = 2, text = "Country 2, City 2" });
    cities.Add(new { value = 6, countrtyId = 2, text = "Country 2, City 3" });
    cities.Add(new { value = 7, countrtyId = 3, text = "Country 3, City 1" });
    cities.Add(new { value = 8, countrtyId = 3, text = "Country 3, City 2" });
    cities.Add(new { value = 9, countrtyId = 3, text = "Country 3, City 3" });

    return cities;
}

protected void RadComboBox2_ItemChecked(object sender, RadComboBoxItemEventArgs e)
{
    var combo = (sender as RadComboBox);

    List<string> selectedCountries = new List<string>();

    foreach (var checkedItem in combo.CheckedItems)
    {
        selectedCountries.Add(checkedItem.Value.ToString());
    }

    RadComboBox3.DataSource = Cities().Where(x => selectedCountries.Contains(Convert.ToString(x.countrtyId)));
    RadComboBox3.DataTextField = "text";
    RadComboBox3.DataValueField = "value";
    RadComboBox3.DataBind();
}

Documentation for the APIs used in this scenario can be found below:

Kind regards,
Attila Antal
Progress Telerik