Answer / guneetinder singh

By using custom validator.

Answer / swethasri

Client Side validation:
A Javascript function can be written to disable/enable the
text box and it can be called under
DrowpDownList_SelectIndexChanged event. We can provide an
if condition and get the required change in javascript
function.

or else

Server side validation:
we can make the dropdownlist 'AutoPostBack' property true.
and under the DrowpDownList_SelectIndexChanged event, we
can disable/enable the textbox.

Answer / rajesh

by using javascript function can be written to
disable/enable the text box and it can be called under
DrowpDownList_SelectIndexChanged event.

Answer / devkranth kishore

U can do it By Adding a Required validator To the textbox
with enabled is false...

no in the Drop downList selected IndexChanged make it
enable True... this will solve the Isssue

Answer / deepak

just write a javascript function like this
on button click or on onkeypress event of text box

function validate()
{
if(document.getelementbyid("ur dropdownlist").value=="other")
{
if(document.getelementbyid("ur textbox").value=="")
{
alert("please enter city name");
return false;
}

}

}

and call like this onkeypress='return validate()'

Answer / sai krishna

In aspx page

<asp:DropDownList ID="DropDownList1" runat="server"
Width="176px">
<asp:ListItem>Pune</asp:ListItem>
<asp:ListItem>Chennai</asp:ListItem>
<asp:ListItem>Hyderabad</asp:ListItem>
<asp:ListItem>Other</asp:ListItem>
</asp:DropDownList>
<asp:TextBox ID="TextBox2"
runat="server"></asp:TextBox>

<script language="javascript" type="text/javascript">
var other1 = window.document.getElementById("TextBox2");
other1.disabled = true;
function ValidateOtherCity()
{
var other = window.document.getElementById
("DropDownList1");
var other2 = window.document.getElementById
("TextBox2");
if(other.value == 'Other')
{
other2.disabled = false;
}
else
{
other2.disabled = true;
}
}
</script>


In aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
DropDownList1.Attributes.Add
("OnChange", "javascript:ValidateOtherCity();");
}

Answer / udai

On_page load
{
RequiredFieldValidator1.Enabled = false;
}

if (DropDownList1.SelectedItem.Text == "Other")
{
RequiredFieldValidator1.Enabled = true;
}
else
{
RequiredFieldValidator1.Enabled = false;
}

Answer / swetha v

Hi Friends,

I hope the below solution helps....

1. Please add the required field validator for the texbox.
2. In Page_Load method, we can add the below statement

Dropdownlist.Attributed.Add
("OnChange","javascript:ValidateOtherCity();")

Add the below javascript function on the aspx page

function ValidateOtherCity()
{
var other = window.document.getElementById
("DropdownlistName");

if(other.value == 'Other')
{
ValidatorEnable(RequiredFieldValidatorName,true);
}
else
{
ValidatorEnable(RequiredFieldValidatorName,false);
}
}

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