how to pass additional parameter to CascadingDropDown?

Question

below is my code, how can i pass Label1.text to CascadingDropDown?

<asp:DropDownList ID="ddl_category_parent" runat="server"></asp:DropDownList>                                                               
<cc1:CascadingDropDown ID="cdd_category_parent" runat="server" Enabled="false" category="ParentCat" loadingtext="loading..." 
 promptvalue="Select a parent category" servicemethod="GetParentCategory"
 servicepath="/webservices/category.asmx" targetcontrolid="ddl_category_parent">
</cc1:CascadingDropDown>


    <WebMethod()> _
    Public Function GetParentCategory(ByVal knownCategoryValues As String, ByVal category As String) As CascadingDropDownNameValue()

        Dim values As New List(Of CascadingDropDownNameValue)()
        Dim parent_cat_name As String

        Dim keyword as String = xxxxxx (Label1.text)

        DT = DBcategory.return_category_detail("Status", "Admin", keyword, "Product", "parent", "", "Active", "")

        For x As Integer = 0 To DT.Rows.Count - 1
            parent_cat_name = DT.Rows(x).Item("name1").ToString
            values.Add(New CascadingDropDownNameValue(HttpUtility.HtmlDecode(parent_cat_name), DT.Rows(x).Item("ID")))
        Next

        Return values.ToArray()

    End Function

Answer 1

Hi @WebSpider ,
As far as I think,you could use the ContextKey to pass the additional parameter.You need to do like this:

1. Set UseContextKey property on the CascadingDropDown to true
2. Change the method signature of your webmethod to accept the contextKey parameter:
   • Public Function GetParentCategory(ByVal knownCategoryValues As String, ByVal category As String,ByVal contextKey As String) As CascadingDropDownNameValue()
3. Set the ContextKey using JavaScript/Jquery. The AJAX CascadingDropDown exposes getter/setter for this property in the DOM:
   • document.getElementById('Label1').set_contextKey('valueyouwant');
   Just like this: <asp:DropDownList ID="ddl_category_parent" runat="server" o nchange="CategoryChanged()"></asp:DropDownList>
   <cc1:CascadingDropDown ID="cdd_category_parent" runat="server" Enabled="false" category="ParentCat" loadingtext="loading..."
   promptvalue="Select a parent category" servicemethod="GetParentCategory"
   servicepath="/webservices/category.asmx" targetcontrolid="ddl_category_parent">
   </cc1:CascadingDropDown>

Javascript:

<s cript type="text/javascript">  
    function CategoryChanged() {  
       $find('<%=Label1.ClientID%>').set_contextKey($get("<%=Label1.ClientID %>").value);  
    }  
</script>  

Code-behind:

 <WebMethod()> _  
             Public Function GetParentCategory(ByVal knownCategoryValues As String, ByVal contextKey As String) As CascadingDropDownNameValue()  
            ......  
            End Function  

Best regards,
Yijing Sun

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