We Keep Coding

Having to click button twice to trigger postback in asp.net

I have some validation code in my searchbutton click event and have been having problems with it having to be clicked twice to work.
Asp Code:
<asp:Button ID="SearchButton" runat="server" Text="Search" Width="148px" OnClick="SearchButton_Click" style="height: 35px" />
Code Behind
protected void SearchButton_Click(object sender, EventArgs e)
{
string title = TitleSearch.Text;
Regex rgx = new Regex("^[0-9A-Za-z ]+$");
if (title != "" && !rgx.IsMatch(title))
{
ErrorLabel.Text = "Special characters are not allowed";
}
else
{
SearchButton.PostBackUrl = "results.aspx";
}
}

does the textbox have postback ? becaus if you change the text in the textbox it will do postback when you leave the textbox.so if you click the button the postback of the textbox fires.
I would check the textbox with java
Add in you page load event "Change EditGroup to the TextBoxName you want to check"
EditGroup.Attributes.Add("onchange", "return SomeTextChanged();");
This will add an onchange event to the textbox and it will call the java function in your aspx page when you click the button
Then in your aspx page you add "Again change EditGroup to the name of the TextBox you want to check"
<script type="text/javascript">
function SomeTextChanged() {
var Entered = document.getElementById('<%= EditGroup.ClientID %>');
if (Entered.value != "" && !Entered.value.match("^[0-9A-Za-z ]+$"))
{
alert("Special characters are not allowed");
document.getElementById('<%= EditGroup.ClientID %>').value = '';
}
else
{
}
}
</script>
So if you enter something that is not allowed you will get a message saying "Special characters are not allowed"
This will also stop you page from executing the rest of the code in the button click event.
And you also need to empty the textbox"i know this is maybe not the best way but if you don't empty the textbox and the user will click the button again it will not run the java code because the text didn't change"
So if if the text is good the java script will do nothing and the button click event will fire

Selected value from database in DropDownList (not GridView)

I work in ASP NET 4.0 and C-sharp.
I have one form page .aspx with this DropDownList (Inside is the ID) and save the value S or N in the matching field in database :
<asp:DropDownList ID="Inside" runat="server" Width="100" CssClass="ddl_Class">
<asp:ListItem Text="-------" Value=""></asp:ListItem>
<asp:ListItem Text="S" Value="S"></asp:ListItem>
<asp:ListItem Text="N" Value="N"></asp:ListItem>
</asp:DropDownList>
I need that when the value of field Inside in database is valid and is not null, in the DropDownList it's selected the value set in the database and disable the DropDownList.
I have tried this code in .cs page without success.
Anybody know how can I do that?
code-behind
InsideDB = dr["Inside"].ToString();
if (!string.IsNullOrEmpty(InsideDB.ToString()))
{
Inside.Text = InsideDB.ToString();
Inside.Enabled = false;
}
else
{
Inside.Enabled = true;
}

Try SelectedValue instead of Text property.
InsideDB = dr["Inside"].ToString();
Inside.Enabled = true;
if (!string.IsNullOrEmpty(InsideDB.ToString()))
{
Inside.SelectedValue = InsideDB.ToString();
Inside.Enabled = false;
}

Try something like
Inside.SelectedIndex = Inside.Items.IndexOf(Inside.Items.FindByText(InsideDB.ToString()));
instead of Inside.Text = InsideDB.ToString();
This assumes that you have an item with that text in the dropdownlist already.

I know this is old post. But this may help others.
Inside.Items.FindByText(InsideDB.ToString()).Selected=true;
Inside.Enabled = false;

Label Does Not Change After TextBox OnTextChanged Event ASP.NET

I have a username TextBox and a Label which should update to (V or X) when the TextBox text is changed. The label is updated only if, for example I press a button which automatically refreshes the page.
Here is the code:
<asp:TextBox ID="username" runat="server" OnTextChanged="checkUsername" Width="80%"></asp:TextBox>
<asp:Label ID="usernameCheck" runat="server" CssClass="checkL"></asp:Label>
And the aspx.cs
protected void checkUsername(object sender, EventArgs e)
{
if (username.Text.Length < 3 || username.Text.Length > 15)
{
//---Label = X (in red)
usernameCheck.Text = "\u2715";
}
else
{
if (myBl.checkUsername(Convert.ToString(username)))
{
//---Label = X (in red)
usernameCheck.Text = "\u2715";
}
else
{
//---Label = V (in green)
usernameCheck.Text = "\u2713";
}
}
}
Thanks for any help.

You need to add AutoPostBack="true" to your TextBox. This will cause it to post back and for that server side event to fire.
There are much better ways of doing what you are trying to accomplish though, most of which do not require a full page postback. I would try to make an AJAX call using the javascript change event, and using something like a callback method.

disable dropdownlist on page load

I have 2 dropdownlists populated from database:
what I want is to disable the second one on page load and when the value of the first one =="1".
here is my second dropdownlist:
<asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="True"
DataSourceID="SqlDataSource2" DataTextField="BName" DataValueField="BId"
OnDataBound="DownList2_DataBound"
OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged">
</asp:DropDownList>
This what I tried to disable the dropdownlist2 (javascript):
<script type="text/javascript">
window.onload = function () {
document.getElementById('DropDownList2').disabled = true;
}
</script>
Tried another thing in C# code:
protected void Page_Load(object sender, EventArgs e)
{
if (DropDownList1.SelectedValue.ToString() == "1")
{
DropDownList2.Enabled = false;
}
}
I even tried this alone in page_load:
DropDownList2.Enabled = false;
The problem is it's disabled on SelectedIndexChanged for dropdownlist1 but not on page load! Is there's something missing in my code?

This statement allow you to set the dropdown2 to disable at page load.
$('#' + '<%=DropDownList2.ClientID%>').attr('disabled',true);
you can do this using Jquery simply as follow:
$(document).ready(function () {
var isPostBack = '<%=IsPostBack%>';
if (isPostBack == 'False' || $('#' + '<%=DropDownList1.ClientID%>').val() == '1') {
//This statement allow you to set the dropdown2 to disable
$('#' + '<%=DropDownList2.ClientID%>').attr('disabled', true);
}
else {
$('#' + '<%=DropDownList2.ClientID%>').attr('disabled', false);
}
$('#' + '<%=DropDownList1.ClientID%>').on("change", function () {
//Your code here
if ($('#' + '<%=DropDownList1.ClientID%>').val() == '1') {
$('#' + '<%=DropDownList2.ClientID%>').attr('disabled', true);
}
else {
$('#' + '<%=DropDownList2.ClientID%>').attr('disabled', false);
}
});
});

It is likely that the DropDownList1.SelectedValue is not equal to "1" on Page Load as I guess you'd be DataBinding it somehow, which would take effect afterwards.
Try adding a SelectedIndexChanged function for DropDownList1 and dis/enabling DropDownList2 here. You can put Enabled="False" in the markup for DropDownList2 to ensure it starts off Disabled.

The issue is likely that document.getElementById('DropDownList2') doesn't find your dropdown list. The ID for the list is a server-side value that doesn't necessarily translate to the client-side ID. If you set ClientIDMode for the control to Static, then the client ID will be DropDownList2. Another option is to access the ClientID property of the control when outputting your JavaScript (if it's inline):
document.getElementById('<%=DropDownList2.ClientID%>').disabled = true;
All that being said, even if that's the case, it'd be better to just start with Enabled="False" as #aaroncatlin suggests so you don't have to wait for the JavaScript to execute before it is disabled.

in ASP.NET the generated ID differs from the asp ID on the component, to access the element from Javascript you need to use <%=DropDownList2.ClientID%> the corresponding javascript will be something like this :
document.getElementById(<%=DropDownList2.ClientID%>).disabled = true;

The DropDownList would have a default selected index of -1 and a null value for selected value. I usually check against the selected index, instead of by value. For example,
if(DropDownList1.SelectedIndex < 1){
// assuming that index 0 holds your value of "1"
DropDownList2.Enabled = false;
}
And #Jacob did rightly point out about you needing to get the proper ClientID for your JavaScript function.

problem with check box in asp .net c#?

The controls on aspx page are like this
Submitted
Submission Date
I want, if the check box is checked, then the textbox will be enabled I wrote
if(chkSubmitted.Checked)
{
txtSubmissionDate.Enabled = true;
}
in the page load event. But when the page is loaded this checkbox having no effect on. Whats going wrong?

If you want the action of clicking the checkbox to enable the textbox, you'll need to do a postback when the box is checked by setting AutoPostBack="True":
<asp:CheckBox runat="server" ID="chkSubmitted" AutoPostBack="True" />
Or, you could use JavaScript:
<asp:CheckBox runat="server" ID="chkSubmitted" onclick="setSubmissionDateEnabled()" />
function setSubmissionDateEnabled()
{
var chkSubmitted = document.getElementById("<%= chkSubmitted.ClientID %>");
var txtSubmissionDate = document.getElementById("<%= txtSubmissionDate.ClientID %>");
txtSubmissionDate.disabled = !chkSubmitted.checked;
}

First set autopostback property to true of checkbox
write following code in checkbox_Selectedindexchanged event
if(chkSubmitted.Checked)
{
txtSubmissionDate.Enabled = true;
}
else
{
txtSubmissionDate.Enabled = false;
}

Thats most likely because the default state of txtSubmissionDate is enabled already.
Try this in your page_load:
txtSubmissionDate.enabled = !chkSubmitted.Checked
To clarify, the textbox should not (!) be enabled when the Checkbox is.

Put this in Page_PreRender event. At this stage it will capture the user affected state of chkSubmitted.