How to hide Dropdownlists?

Hi,

Step 1:   Design All the drop down and do not use the different drop down for different purpose. Calculate the maximum number of drop downs required. You can assign the different data source to the same control...

Step 2:  Set the visible false to the unwanted drop down initially. Set the data source to the first control and try to use the DataTextField and DataValueField...Because the DataTextField should be used to display text and DataValueField is unique value.

Step3: Write the indexchanged event to the dropdown and enable the autopostback=true property. Then write the logics to get the value from the selected dropdown and populate the value to the subsequent dropdown and make that drop down as visible.

I would suggest you to use the update panel from the Ajax. Because it will be fast to render and avoid the post back. Otherwise it will take too much time to load and render every time when you select the drop down control.

yea., but i thought not only hiding dropdown's but also simultanious binding of respective drop down lists with previous ddl selected value

such case server side coding is necessary other wise client side coding can be done

hi,

Agree with pramod.

Only one thing wat add,
Hide show logic , you can also write using JAVA SCRIPT or JQuery,
it reduce ur server call. hence increace performance.

Hi , i didn't observe u r hide princeple here iam explaining it

First put all dropdown's visiblity false in page_load event except first drop down
then set every drop down visibility true in it's previous drop down selected index changed event like below

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
           
            DropDownList2.Visible = false;
            ...
            ...   
            DropDownList10.Visible = false;
           
        }
    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList2.Visible = true;
       
    }
    protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList3.Visible = true;
    }
    protected void DropDownList3_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList4.Visible = true;
    }

Bind the first drop down in page_load event and bind each other drop down in pervious drop down's "onselectedindexchanged" event like below

In each dropdown's selected index changed event the other drop down bind will occur
 
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DropDownList1.DataSource = datatable;
            DropDownList1.DataBind();
        }
    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
              //write sql query based on first drop down selected text or selected value
        string strsql = "Select * from table where coulumn=" + DropDownList1.SelectedItem.Text;
        ...
        ... //code to fill datatable2
        ...
        DropDownList2.DataSource = datatable2;
        DropDownList2.DataBind();
       
    }
    protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
    {
        string strsql = "Select * from table where coulumn=" + DropDownList2.SelectedItem.Text;
        ...
        ... //code to fill datatable3
        ...
        DropDownList3.DataSource = datatable3;
        DropDownList3.DataBind();
    }
    protected void DropDownList3_SelectedIndexChanged(object sender, EventArgs e)
    {
        string strsql = "Select * from table where coulumn=" + DropDownList3.SelectedItem.Text;
         ...
        ... //code to fill datatable4
        ...
        DropDownList4.DataSource = datatable;
        DropDownList4.DataBind();
    }


I hope you would understand...