.NET Tutorials, Forums, Interview Questions And Answers
Welcome :Guest
Sign In
Register
 
Win Surprise Gifts!!!
Congratulations!!!


Top 5 Contributors of the Month
Easy Web
Imran Ghani
Post New Web Links

Clear a DropDownList from code behind.

Posted By:      Posted Date: September 01, 2010    Points: 0   Category :ASP.Net
 
Hi All,I want to clear the value of DropDownList from codebehind and i have found followingsolution.ddl.Items.Clear(); andddl.DataSource=null; ddl.DataBind();Now the question is which is the best solution and why?


View Complete Post


More Related Resource Links

Dropdownlist appears to be null in code behind

  

I have a weird problem...

I have a web part form, with one of the dropdownlist, when referenced in code behind, happes to be null.

Common.bindMultiChoices(ddlPly4, oEnquiriesList, "Ply 4 Type (Paper)", "Select Ply 4", null); 

But at front user control file, I do have:

<tr><td><asp:DropDownList ID="ddlPly4" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlPly4_OnSelectedIndexChanged" /&

AJAX DropDownList won't populate.. error500.. code is working though.

  

Here's what I have.  I was able to debug and traverse through the webservice and return teh array back into the first call method of: return new CarsService()..  But back in the page_load method, I can't get it to update and show up in the page.  what am I doing wrong?!?!

thanks.


<asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional">
                 
                    <ContentTemplate>
                     
                    <cc1:CascadingDropDown ID="CascadingDropDown1" runat="server" TargetControlID="DropDownList1"
                     Category="Make" PromptText="Please select a make" LoadingText="[Loading makes...]"  
             

Items added through Javascript to a dropdownlist are not accessible through code behind

  

Hi All,

I am successfully able to add new items to a drop down list using Javascript.

The script I am using is 

        function FillJavaScriptValues() {
           
            var ddlDeliveryVan;
            ddlDeliveryVan = document.getElementById("DropDownList1");
            var opt = document.createElement("option");

Populating DropDownList in FormView from Code Behind

  

On my formview I have a drop down list that is populated with the names of the files in a certain directory. This works fine, but when the drop down list selected value is bound to the database field I get the following error :

'ImageFileDropDownList' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value

I have setup other drop down lists in the same formview populated from SqlDataSources and these all work fine. I can see perhaps why this is an issue because I have not specified a DataValueField or a DataTextField for this drop down that is populated in code (whereas I can for the SQL bound ones) because I'm not sure what these settings would be.

I need to have a "blank" option as well so that the field does not default to the first value in the list.

My code (I have stripped out some meaningless controls) :

<asp:FormView ID="FormView1" runat="server" DataKeyNames="BannerID" DataSourceID="SqlDataSource2" OnItemDeleted="FormView1_ItemDeleted">
  <EditItemTemplate>
    <table width="100%" cellspacing="0" cellpadding="4">                          
      <tr><td>ID:</td><td>
        <asp:Label 

Clear DropDownList on Postback

  
 

i have two radio button list on my page

on my Frist Index there is a panel with Drop Down List

and on Second Index there is a static variable in which i am storing value as Pending


now as soon as i select my Second RadioButtonList it also stores the DropDown List Value

how i can clear the DropDown List Value?

My Code

protected void Button2_Click(object sender, EventArgs e)
    {
        string day = DropDownList1.SelectedItem.Text;
        string day1 = DropDownList4.SelectedItem.Text;

        string month = DropDownList2.SelectedItem.Text;
        string month1 = DropDownList5.SelectedItem.Text;

        string year = DropDownList3.SelectedItem.Text;
        string year1 = DropDownList6.SelectedItem.Text;

        string date1 = day + "/" + month + "/" + year;
        string date2 = day1 + "/" + month1 + "/" + year1;
        DataSet ds = new DataSet();

        ds = ob.GetDate_Search("Death Certificate", pending, date1, date2);
        GridView1.DataSource = ds;
        GridView1.DataBind();

    }


protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (RadioButtonList1.SelectedIndex == 0)
        {
            pending = "Pending&quo

Code Optimized Web Development Profile (VS 2010 and .NET 4.0 Series)

  
When you first run VS 2010 it prompts you to select an IDE profile to use. The profile you select will configure how tool windows are displayed/docked in the IDE by default and set the default keyboard shortcuts. You can then customize any of these settings by using the Tools->Options menu within the IDE and then override/change them. You can also later reset your profile and pick a different one by choosing the Tools->Import and Export Settings menu command.

Free Code Snippets - ASP.NET

  
You Can Find Useful ASP.NET Related Posts on the above link.

Free Code Snippets - C#

  
Free C# Code Snippets

call JavaScript - jQuery code from ASP.NET Server-Side

  
jQuery got so close to me lately that I can see myself adding the scripts to my project almost unconsciously. The thing is, jQuery is very useful for me, in almost all situations and it has been a do or die enhancement for all my project since I first put my hands on it.

Of course while using it, you encounter few situations which need a bit of research to solve, mostly when you are trying to combine it with some other technologies like: UpdatePanels and ASP.NET Ajax. For instance there are many situations when I would like to run some jQuery magic based on some decision that I make on the server side.

jQuery: Styling DropDownList Alternating Items (Rows)

  
In the following example, I will show how you can style any asp:dropdownlist very easily.

The example demonstrates how you can change alternating row items background color, using the fadeTo() to add a nice touch in the dropdownlist. You can change alt rows with a couple lines.

call JavaScript - jQuery code from ASP.NET Server-Side

  
jQuery got so close to me lately that I can see myself adding the scripts to my project almost unconsciously. The thing is, jQuery is very useful for me, in almost all situations and it has been a do or die enhancement for all my project since I first put my hands on it.

Of course while using it, you encounter few situations which need a bit of research to solve, mostly when you are trying to combine it with some other technologies like: UpdatePanels and ASP.NET Ajax. For instance there are many situations when I would like to run some jQuery magic based on some decision that I make on the server side

Microsoft StyleCop: Source Code Analyzer for C#

  
StyleCop is similar in many ways to Microsoft Code Analysis (specifically FxCop), but there are some important distinctions. FxCop performs its analysis on compiled binaries, while StyleCop analyzes the source code directly. For this reason, FxCop focuses more on the design of the code, while StyleCop focuses on layout, readability and documentation. Most of that information is stripped away during the compilation process, and thus cannot be analyzed by FxCop.

Working with DropDownList and ListBox Controls in ASP.NET

  
"In my application i am using dropdownlist to display all categories from a table. When the user clicks this control I display all records in that category. Category table also contains column called color.

I wanted display some categories in dropdown list different color and others in different color using ASP.NET."-Anonymous

ASP.NET DropDownList Web Control, Part 1

  
Anybody with much experience in ASP has written an include file function for populating the contents of a SELECT dropdown list with entries from a database. Some of the more advanced users have even gone so far as to add caching to their function to reduce database hits for these rarely changing menu options. Naturally, these same techniques are going to be used with ASP.NET, but with a new programming object model. ASP.NET provides a web control, the DropDownList, which can be used for the same purposes as our custom built SELECT tag from Classic ASP.

Declaring a DropDownList in ASP .Net

  
A DropDownList is also commonly known as combo box. It can contain multiple data members, but unlike a normal list box the users can choose only one value from this control. Though the functionality of this DropDownList is much like a Single Row Select List Box, a DropDownList can save a lot of GUI space as it is rendered on a Single line and is expanded only when the user clicks on the Control

Multiple Column Dropdownlist for the ASP.NET DataGrid

  
Based on my previous control "Multiple Column DropDownList for ASP.NET", I received many emails asking for the same control to be used in the DataGrid for web applications. Here we go.. This control can be used as the regular MS DropDownList in the DataGrid and also as a regular dropdownlist. It has all the properties, like DataTextField, DataValueField, DataSource, SelectedIndex etc. The download file contains the samples both in VB.NET and C#. In this sample, I have used the Northwind database of SQL Server.
Categories: 
ASP.NetWindows Application  .NET Framework  C#  VB.Net  ADO.Net  
Sql Server  SharePoint  Silverlight  Others  All   

Hall of Fame    Twitter   Terms of Service    Privacy Policy    Contact Us    Archives   Tell A Friend