handling drop down in asp.net/C#

Hi Swati,


I changed my code to support a web application.

Use it.



    private int numberofchangeddropdown = 0;
    private System.Collections.ArrayList dropdowns = new System.Collections.ArrayList();

    protected void Page_Load(object sender, EventArgs e)
    {
        foreach (Control c in this.Controls)
        {
            if (c is DropDownList)
            {
                DropDownList obj = (DropDownList)c;
                obj.SelectedIndexChanged += new System.EventHandler(this.Dropdownlist_SelectedIndexChanged);
                //You bind the same event to all the dropdowns.
            }
        }
    }
    protected void Dropdownlist_SelectedIndexChanged(object sender, EventArgs e)
    {
        //You check whether you already counted that dropdown. Otherwise if you change one dropdown two times it will count 2 which is not correct.

        if (!dropdowns.Contains(sender))
        {
            dropdowns.Add(sender);
            numberofchangeddropdown++;
        }
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        Page.RegisterClientScriptBlock("msg", "");
    }

Please try code first and let me know...i just tried it in my local and its working..
 

Hey to reply to urs answer..
I dont know the total number of drop-down to bind it in the code..Its dynamic..A page retrieves the number of drpdown according to some case..

Hi swati,

My code works for any number of dropdowns. You can use it. But please do not forget to tick Do you like this answer checkbox.

In my code you have only one event and you bind all the dropdowns to that event.

If you download the code from my previous reply, it will be easier for you.



If you are using a web application, replace ComboBox with DropDownList. There will be no other difference.




        private int numberofchangeddropdown = 0;
        private ArrayList dropdowns = new ArrayList();

        public Form1()
        {
            InitializeComponent();

            foreach (Control c in this.Controls)
            {
                if(c is ComboBox)
                {
                    ComboBox obj = (ComboBox)c;
                    obj.SelectedIndexChanged += new System.EventHandler(this.comboBox_SelectedIndexChanged);
                    //You bind the same event to all the dropdowns.
                }
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show("You changed "+ numberofchangeddropdown.ToString() + " dropdowns !");
        }

        private void comboBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            //You check whether you already counted that dropdown. Otherwise if you change one dropdown two times it will count 2 which is not correct.

            if (!dropdowns.Contains(sender))
            {
                dropdowns.Add(sender);
                numberofchangeddropdown++;
            }
        }

If you are having dynamic controls then you can use this ..
foreach (Control c in this.form1.Controls)
   if (c.GetType().Name == "DropDownList")
      if (((DropDownList)c).SelectedIndex != 0)
         cnt += 1;
Page.RegisterClientScriptBlock("msg", "");
cnt = 0;

Hey again to  clarify..I have a page which retrieves n number of dropdown .A user can change the value of any number of dropdown(Page is editable)..and same number should appear in the dialog box..whenever he saves changes..

Hi Swati,


It's not difficult.

I wrote a small application for you. Download it and check. It supports any number of dropdowns.


If my answer helps you, please do not forget to tick 'Do you like this answer' checkbox.

Have a global variables for the count and check the count and display the alert..
static int cnt = 0;
protected void Page_Load(object sender, EventArgs e)
{
//your page load code..
}
protected void Dropdownlist1_SelectedIndexChanged(object sender, EventArgs e)
{
cnt += 1;
}
protected void Dropdownlist2_SelectedIndexChanged(object sender, EventArgs e)
{
cnt += 1;
}
protected void Dropdownlist3_SelectedIndexChanged(object sender, EventArgs e)
{
cnt += 1;
}
protected void Button1_Click(object sender, EventArgs e)
{
Page.RegisterClientScriptBlock("msg", "");
}
and this can be customized properly to check if the dropdown is clicked twice by having a seperate variable for each dropdown and check in the button click..

Hey that was my supposition to alter the value of three no. of dropdown..A user can change 'n' no. of dropdown ..and the same should appear in the dialog box...Pls help me with this..
Thanks