CascadingDropDown Missing parameter: knownCategoryValues

I am having some trouble getting CascadingDropDown lists to work, its displaying the Method 500 error inside the list. I have tried all the common solutions to this and still no luck.

I was originally getting the following error:

System.ArgumentException: Invalid method name 'getcategories', method names are case sensitive. The method name 'GetCategories' with the same name but different casing was found. Parameter name: methodName

Which is odd because I am definately setting the method name in the correct case but it was sending it in lowercase (even though chrome showed the page as sending it in the correct case). Anyhow I worked around this by changing the method name itself to lowercase. This now brings up a new error:

System.InvalidOperationException: Missing parameter: knownCategoryValues.

If anyone could shed any light on either of these problems that would be a great help, I've spent way too long on this problem.

Thanks.

UPDATED Code:

<ajaxToolkit:ToolkitScriptManager EnablePageMethods="true" ID="ToolkitScriptManager1" runat="server">
</ajaxT开发者_开发问答oolkit:ToolkitScriptManager>
<ajaxToolkit:CascadingDropDown
    ID="CascadingDropDown1"
    runat="server"
    TargetControlID="mmCategory" 
    Category="Category" 
    PromptText="Select a category" 
    ServicePath="~/DropDownLists.asmx"
    ServiceMethod="GetCategories" />
<ajaxToolkit:CascadingDropDown
    ID="CascadingDropDown2"
    runat="server"
    TargetControlID="mmTemplate"
    ParentControlID="mmCategory"
    PromptText="Select a template"
    ServiceMethod="GetTemplates"
    ServicePath="~/DropDownLists.asmx"
    Category="Template" />
Category: <asp:DropDownList ID="mmCategory" runat="server"/><br/>
Template: <asp:DropDownList ID="mmTemplate" runat="server"/><br/>

Web Service File:

using System;
using System.Web;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Web.Services;
using System.Web.Services.Protocols;
using AjaxControlToolkit;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Linq;

/// <summary>
/// Summary description for TemplateData
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService()]

public class DropDownLists : System.Web.Services.WebService
{

    public DropDownLists()
    {
        //Uncomment the following line if using designed components 
        //InitializeComponent(); 
    }

    [System.Web.Services.WebMethod]
    [System.Web.Script.Services.ScriptMethod]
    public CascadingDropDownNameValue[] getcategories(string knownCategoryValues, string category)
    {

        List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>();
        values.Add(new CascadingDropDownNameValue("test 1", "1"));
        values.Add(new CascadingDropDownNameValue("test 2", "2"));
        return values.ToArray();

        /*using (MiscDataContext dc = new MiscDataContext())
        {
            var CatQuery = from D in dc.Templates
                        select new {  D.Category  }
                            into CatQueryResults
                                select CatQueryResults;

                foreach (var CatResult in CatQuery)
                {
                    string CatReturn = CatResult.Category;
                    values.Add(new CascadingDropDownNameValue(CatReturn, CatReturn));
                }
                return values.ToArray();
         }*/

    }


    [System.Web.Services.WebMethod]
    [System.Web.Script.Services.ScriptMethod]
    public CascadingDropDownNameValue[] GetTemplates(string knownCategoryValues, string category)
    {

        StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
        string varCat;
        varCat = kv["Category"];


        List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>();
        values.Add(new CascadingDropDownNameValue("test 3", "3"));
        values.Add(new CascadingDropDownNameValue("test 4", "4"));
        return values.ToArray();
        /*using (MiscDataContext dc = new MiscDataContext())
        {
            var CatQuery = from D in dc.Templates
                        where(D.Category == varCat)
                        select new {  D.ID, D.Name  }
                        into CatResult
                        select CatResult;

                foreach (var CatResult in CatQuery)
                    {
                        int ID = (int)CatResult.ID;
                        string Name = CatResult.Name;
                        values.Add(new CascadingDropDownNameValue(Name, Convert.ToString(ID)));
                    }
                    return values.ToArray();
            }*/
        }
}

In order to be usable with a CascadingDropDown, your web method's prototype must be:

[System.Web.Services.WebMethod]
[System.Web.Script.Services.ScriptMethod]
public CascadingDropDownNameValue[] GetCategories(
    string knownCategoryValues, string category)
{
}

If you assign something to the ContextKey property of the extender, that prototype becomes:

[System.Web.Services.WebMethod]
[System.Web.Script.Services.ScriptMethod]
public CascadingDropDownNameValue[] GetCategories(
    string knownCategoryValues, string category, string contextKey)
{
}

The knownCategoryValues parameter represents the current selection in the master dropdown. You should pass it to CascadingDropDown.ParseKnownCategoryValuesString() to obtain its actual value.