How to take selected value of dropdownlist in web method using cascading dropdownlist

Hi All,

I am using C# 2.0 and ajax1.0.I am trying to fill dropdownlist using ajax cascading toolkit but I am not able to populate the dropdownlist.  My question is how do I take input value of parent dropdownlist in web service the fill the data that is in my senario I have subprod parent (fill on page load) and then Prod fill on subprod selection.  The web service method I used is


public CascadingDropDownNameValue[] GetProd(string knownCategoryValues, string category)

        StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
        string subgrp = null ;
      //  if (!kv.ContainsKey("PGM_GRP_CODE") || !Int32.TryParse(kv["PGM_GRP_CODE"], out subgrp))
        if (!kv.ContainsKey("PGM_GRP_CODE") )
            return null;
        DsprdTableAdapters.SPGETPRODUCT_GIVENSUBTableAdapter prd = new DsprdTableAdapters.SPGETPRODUCT_GIVENSUBTableAdapter();
        Dsprd.SPGETPRODUCT_GIVENSUBDataTable prdgrp = prd.GetProd(subgrp);
        List values = new List();
        foreach (DataRow dr in prdgrp)
            values.Add(new CascadingDropDownNameValue((string)dr["PM_PRD_NAME"], dr["PM_PRD_CODE"].ToString()));
        return values.ToArray();


cascading toolkit I definded as 

                                       PromptText="Choose a Product...." 
                                       LoadingText="Please wait ..." 
Please suggest.
4/15/2008 6:23:19 AM 13973 articles. 1 followers. Follow

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Thank you for your post! 

Cascading dropdownlist use   StringDictionary kv = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues) to change it into a StringDictionary type ojbect. Here the source code shows how it works:

        public static StringDictionary ParseKnownCategoryValuesString(string knownCategoryValues)
            // Validate parameters
            if (null == knownCategoryValues)
                throw new ArgumentNullException("knownCategoryValues");

            StringDictionary dictionary = new StringDictionary();
            if (null != knownCategoryValues)
                // Split into category/value pairs
                foreach (string knownCategoryValue in knownCategoryValues.Split(';'))
                    // Split into category and value
                    string[] knownCategoryValuePair = knownCategoryValue.Split(':');
                    if (2 == knownCategoryValuePair.Length)
                        // Add the pair to the dictionary
                        dictionary.Add(knownCategoryValuePair[0].ToLowerInvariant(), knownCategoryValuePair[1]);
            return dictionary;

Please don't forget to reset your application by saving your web.config file without any modifications before you start your dubugging work. 

Another useful method is:

  1. Right click on your web service name, choose "view in broswer".
  2. Click "GetInstructorsForSchool"
  3. Add "category:selected option value(not text)" as the value of knownCategoryValues and set category to your category name, which was defined in your *.aspx file.   For example knownCategoryValues="school:1"   category ="school";

         cc1:CascadingDropDown ID="CascadingDropDown1" runat="server" TargetControlID="dlSchool"
            Category="School" PromptText="Select a school" ServicePath="WebSerivce/SchoolService.asmx"
            ServiceMethod="GetSchools" LoadingText="Load Text...">

     4.  Click "invoke" button and check if the result is what you want.

This method is usually used to check if your web service works properly.

 Best Regards,

Jin-Yu Yin
Microsoft Online Community Support
4/22/2008 2:00:39 AM

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