Asp.net web form dropdownlist not changing selected value

Question

0.00/5 (No votes)

See more:

I have this below code which I am using to change the selected value of dropdownlist. This dropdownlist items are not data-bound and I have added items to them at design time.

C#

if (dataTable.Rows.Count > 0 && dataTable.Columns.Count > 0)
{
  if (dataTable.Rows[0]["IsSpeechActive"].ToString().Equals(bool.TrueString)) { chkSpeechActive.Checked = true; } else { chkSpeechActive.Checked = false; }
  ddlSL1.SelectedValue = dataTable.Rows[0]["Value1"].ToString(); //en-us
  ddlSL2.SelectedValue = dataTable.Rows[0]["Value2"].ToString(); //1.0
  ddlSL3.SelectedValue = dataTable.Rows[0]["Value3"].ToString(); //1.5
  ddlSL4.SelectedValue = dataTable.Rows[0]["Value4"].ToString(); //default
  ddlSL5.SelectedValue = dataTable.Rows[0]["Value5"].ToString(); //0.5
}
else
{
  ShowMessage("Could not find user speech details");
}

ASP.NET

<asp:DropDownList ID="ddlSL5" CssClass="cm-input-dataform-select cm-input-font" runat="server">
  <asp:ListItem Text="0.0" Value="0.0"></asp:ListItem>
  <asp:ListItem Text="0.1" Value="0.1"></asp:ListItem>
  <asp:ListItem Text="0.2" Value="0.2"></asp:ListItem>
  <asp:ListItem Text="0.3" Value="0.3"></asp:ListItem>
  <asp:ListItem Text="0.4" Value="0.4"></asp:ListItem>
  <asp:ListItem Text="0.5" Value="0.5"></asp:ListItem>
  <asp:ListItem Text="0.6" Value="0.6"></asp:ListItem>
  <asp:ListItem Text="0.7" Value="0.7"></asp:ListItem>
  <asp:ListItem Text="0.8" Value="0.8"></asp:ListItem>
  <asp:ListItem Text="0.9" Value="0.9"></asp:ListItem>
  <asp:ListItem Text="1.0" Value="1.0"></asp:ListItem>
</asp:DropDownList>

In the code above the first dropdown works fine but others are not changing the value to the one that I am fetching from the DB and setting them to.

Please advise as to what is wrong? A weird error this is.

What I have tried:

I deleted the asp.net web form and re-created it.

Posted 16-Dec-18 2:51am

Christopher Fernandes

Updated 17-Dec-18 2:54am

Add a Solution

2 solutions

Solution 1

First off, if you are pre-selecting values at SelectedIndexChanged event of DropDownList, then you need to set AutoPostback to TRUE to trigger the SelectedIndexChanged event.

Second, if you are binding and doing the pre-selection at Page_Load event, then make sure you wrap your code within !IsPostback block.

Third, try to do something like this to pre-select value based from the data in your database:

C#

ListItem item = ddlSL5.Items.FindByValue(dataTable.Rows[0]["Value5"].ToString());
if (item != null){
     	ddlSL5.ClearSelection();
     	item.Selected = true;
}

Do the same for the rest of your DropDownLists.

Posted 16-Dec-18 16:11pm

Vincent Maverick Durano

Updated 16-Dec-18 16:12pm

v2

Comments

Christopher Fernandes 17-Dec-18 0:32am

All listitems in all dropdownlist are added at design time. There is no data binding & index change event that I am using in this form. Only trying to select values in all dropdownlist with what is fetched from the database table at page load & update button click event.

Vincent Maverick Durano 17-Dec-18 1:04am

The code provided doesn't matter if you were added items on design time. Have you tried it?

Christopher Fernandes 17-Dec-18 1:29am

I am trying this code now

string value = dataTable.Rows[0]["Value5"].ToString();
if (ddlSL5.Items.FindByValue(value) != null) { ddlSL5.Items.FindByValue(value).Selected = true; }

Even this is not working. Is this because the list items are hard coded and not databound to the dropdownlist.

Christopher Fernandes 17-Dec-18 1:53am

the above code does not work

Vincent Maverick Durano 17-Dec-18 7:57am

What is the value of the value variable? does the value of your value variable exists in one of your DropDownList?

Christopher Fernandes 17-Dec-18 8:42am

It is a temp string variable to check what value is fetched from the database.

Vincent Maverick Durano 17-Dec-18 8:49am

What is the value stored in it? Have you tried debugging it?

Christopher Fernandes 17-Dec-18 1:56am

The code is not working because the datarow type in the datatable is decimal. It work for text values only see the question and the commented part.

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Christopher Fernandes · Accepted Answer · 2018-12-17T02:54:00

Solution 2

This code below solved the issue

C#

string value = ""; decimal rowvalue;
rowvalue = decimal.Parse(dataTable.Rows[0]["Value5"].ToString());
value = Convert.ToString(rowvalue.ToString("0.0"));
if (ddlSL5.Items.FindByValue(value) != null) { ddlSL5.Items.FindByValue(value).Selected = true; }

Posted 17-Dec-18 2:54am

Christopher Fernandes