Problems with cascading dropdown and duplicate items

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Hi, I have a problem that my dynamic dropdowns make duplicate items.
I selected change event, where I fill in the dropdown number 2 based on what is selected in dropdown number 1. But every time I fill it, it makes double content. And I think I've tried everything.

C# code

SelectedIndexChanged

protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
   {
       //PlaceHolder1.Controls.Clear();

       XmlDocument doc = new XmlDocument();

       doc.Load(Server.MapPath("./xmlReBikeInfo/InfoBikeResponse.xml"));


       Table table = (Table)PlaceHolder1.FindControl("Table1");

       if (table != null)
       {


           for (int i = 0; i < Rows; i++)
           {

               DropDownList ddl = (DropDownList)PlaceHolder1.FindControl("ddlBike_" + i + "");

               //Use Request objects for getting the previous data of the dynamic textbox

               string biketype = ddl.SelectedValue;

               HiddenField hdnSize = (HiddenField)PlaceHolder1.FindControl("hdnSize_" + i + "");


               DropDownList ddlSize = (DropDownList)PlaceHolder1.FindControl("ddlSize_" + i + "");
               ddlSize.CssClass = "dropdown";
               //ddlSize.SelectedValue = "";
               ddlSize.Visible = true;


               TextBox txt = (TextBox)PlaceHolder1.FindControl("txtPrice_" + i + "");

               HiddenField hdnCykelPris = (HiddenField)PlaceHolder1.FindControl("txtHdnCykelPris_" + i);


               HiddenField hdnAccPris = (HiddenField)PlaceHolder1.FindControl("txtHdnAccPris_" + i);

               string number1;

               string number2;


               XDocument xdoc = XDocument.Load(Server.MapPath("./xmlReBikeInfo/InfoBikeResponse.xml"));
               var bikeSizes = xdoc.Descendants("BikeType")
                   .Where(x => x.Element("TypeName").Value == biketype)
                   .SelectMany(x => x.Descendants("SizeName").Select(y => y.Value))
                   .ToList();

               var bikePrice = xdoc.Descendants("BikeType")
                   .Where(x => x.Element("TypeName").Value == biketype)
                   .SelectMany(x => x.Descendants("TypePriceVat").Select(y => y.Value))
                   .ToList();

               var bikeAcc = xdoc.Descendants("Accessorie")
                   .Where(x => x.Element("AccessorieName").Value == biketype)
                   .SelectMany(x => x.Descendants("AccessoriePriceVat").Select(y => y.Value))
                   .ToList();
               decimal result = 0;
               if (biketype == "0")
               {

                   txt.Text = "";


               }
               if (biketype == "Touring")
               {


                   foreach (string s in bikeSizes)
                   {

                       ddlSize.Items.Add(new ListItem(s + ""));

                   }

                   foreach (string p in bikePrice)
                   {


                       hdnCykelPris.Value = p.ToString();
                       string accPrice = "";

                       if (hdnAccPris.Value == "")
                       {
                           accPrice = "0";
                       }
                       else
                       {
                           accPrice = hdnAccPris.Value;
                       }

                       number1 = hdnCykelPris.Value;
                       number2 = accPrice.ToString();

                       result = decimal.Parse(number1) + decimal.Parse(number2);


                       txt.Text = result.ToString();


                       //txt.Text = hdnCykelPris.Value;
                       //litSum.Text = txt.Text;


                   }

                   ddlSize.Visible = true;


               }
               if (biketype == "Junior Bike")
               {


                   foreach (string s in bikeSizes)
                   {

                       ddlSize.Items.Add(new ListItem(s + ""));

                   }


                   foreach (string p in bikePrice)
                   {

                       hdnCykelPris.Value = p.ToString();




                       string accPrice = "";

                       if (hdnAccPris.Value == "")
                       {
                           accPrice = "0";
                       }
                       else
                       {
                           accPrice = hdnAccPris.Value;
                       }

                       number1 = hdnCykelPris.Value;
                       number2 = accPrice.ToString();

                       result = decimal.Parse(number1) + decimal.Parse(number2);


                       txt.Text = result.ToString();

                       //txt.Text = hdnCykelPris.Value;
                   }

               }
               if (biketype == "MTB")
               {



                   foreach (string s in bikeSizes)
                   {


                       ddlSize.Items.Add(new ListItem(s + ""));


                   }

                   foreach (string p in bikePrice)
                   {

                       hdnCykelPris.Value = p.ToString();


                       string accPrice = "";

                       if (hdnAccPris.Value == "")
                       {
                           accPrice = "0";
                       }
                       else
                       {
                           accPrice = hdnAccPris.Value;
                       }

                       number1 = hdnCykelPris.Value;
                       number2 = accPrice.ToString();

                       result = decimal.Parse(number1) + decimal.Parse(number2);


                       txt.Text = result.ToString();

                       //txt.Text = hdnCykelPris.Value;
                   }


               }
               if (biketype == "Classic E")
               {





                   foreach (string s in bikeSizes)
                   {
                       ddlSize.Items.Clear();
                       ddlSize.Items.Add(new ListItem(s + ""));

                       //ddlSize.ClearSelection();
                   }
                   ddlSize.Visible = true;

                   foreach (string p in bikePrice)

                       hdnCykelPris.Value = p.ToString();


                   string accPrice = "";

                   if (hdnAccPris.Value == "")
                   {
                       accPrice = "0";
                   }
                   else
                   {
                       accPrice = hdnAccPris.Value;
                   }

                   number1 = hdnCykelPris.Value;
                   number2 = accPrice.ToString();

                   result = decimal.Parse(number1) + decimal.Parse(number2);


                   txt.Text = result.ToString();


               }


           }

What I have tried:

Clearselection method, clear items method before filling.

And this method

public static void RemoveDuplicateItems(DropDownList ddl)
{

for (int i = 0; i < ddl.Items.Count; i++)
{
ddl.SelectedIndex = i;
string str = ddl.SelectedItem.ToString();
for (int counter = i + 1; counter < ddl.Items.Count; counter++)
{
ddl.SelectedIndex = counter;
string compareStr = ddl.SelectedItem.ToString();
if (str == compareStr)
{
ddl.Items.RemoveAt(counter);
counter = counter - 1;
}
}
}
}

Posted 5-Mar-18 23:49pm

Martin Lauritsen

Updated 5-Mar-18 23:55pm

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#realJSOP · Answer 1 · 2018-03-05T23:54:00

Solution 1

You should remove the duplicates before binding the collection to the dropdownlist.

In all honestly if you don't want duplicates in your collection, maybe you should examine the mechanism that adds them to the database, and prevent them from being duplicated (if that's possible).

Posted 5-Mar-18 23:54pm

#realJSOP

Comments

Martin Lauritsen 6-Mar-18 6:00am

i triede that, with the method above. i callede the method as the first thing in the SelectedIndexChanged event. but it didtn work, it keeps duplicating items

Maciej Los · Answer 2 · 2018-03-05T23:56:00

Solution 2

I'm not sure i understand you well... But, if you would like to get unique data, you can use Distinct() method[^]:

C#

var bikeSizes = xdoc.Descendants("BikeType")
    .Where(x => x.Element("TypeName").Value == biketype)
    .SelectMany(x => x.Descendants("SizeName").Select(y => y.Value))
    .Distinct() //here!
    .ToList();

Posted 5-Mar-18 23:56pm

Maciej Los

Comments

Martin Lauritsen 6-Mar-18 6:03am

I have an dropdown, that every time i call the SelectedIndexChanged event, it duplicates items, so if i have 123 then i call SelectedIndexChanged and it becomes 123123, it keeps adding values to all dropdowns.

Martin Lauritsen 6-Mar-18 6:04am

distinct did not work

Maciej Los 6-Mar-18 6:15am

It works as expected. Your code is not working as you wish. Debug it to find out where you've made mistake(s).