TextBox value not assigning to variable in asp.net

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JavaScript

function outputtax()
 {
 var tamount = parseFloat(document.getElementById('<%=txtpsubtotal.ClientID%>').value);
 var cash = parseFloat(document.getElementById('<%=txtpdiscount.ClientID%>').value);

 if (isNaN(tamount) != true && isNaN(cash) != true )
  {
    document.getElementById('<%=txtPtotalamout.ClientID%>').value =
       Math.round(parseFloat(document.getElementById('<%=txtpsubtotal.ClientID%>').value)
  - parseFloat(document.getElementById('<%=txtpdiscount.ClientID%>').value))
      return false;
    }

  }

<asp:TextBox ID="txtPtotalamout" runat="server" ReadOnly="true">
                                          </asp:TextBox>

**.CS**

C#

objsupplyPL.totalamount = Convert.ToDouble(txtPtotalamout.Text.ToString());

Value is displaying on the textbox but when i click save button `txtptotalamount` is getting
`null` value.If I placed `readonly="false"` it's working fine.

Posted 13-Sep-13 5:42am

Bhagavan Raju M

Updated 13-Sep-13 6:16am

v3

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Comments

Dholakiya Ankit 13-Sep-13 23:50pm

why you are assigning readonly to textbox?

Bhagavan Raju M 14-Sep-13 0:48am

User should not edit the text box

Dholakiya Ankit 14-Sep-13 0:55am

so you are adding value through javascript and then taking that value from c# so assingning readonly =false does not get a solution?

Bhagavan Raju M 15-Sep-13 9:59am

@dholakiya what you said is right.

3 solutions

Solution 3

Try adding

C#

protected void Page_Load(object sender, EventArgs e)

{
 if(!IsPostBack)
 {
   txtPtotalamout.Attributes.Add("readonly","readonly");
 }
}

Posted 13-Sep-13 10:04am

JoCodes

Comments

Bhagavan Raju M 14-Sep-13 0:50am

@jocodes its not working . I am getting empty string. Thanks for ur effort

Solution 1

please put more detail, are you sure you didn't make the other textboxes readonly=true ?

Posted 13-Sep-13 6:47am

Mehdy Moini

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Nitin Singh India · Accepted Answer · 2013-09-13T07:44:00

When you set the value of control through JavaScript it will get set regardless of the server side read-only property.
However when you do a postback through button's click, that value will be part of the postback variable. When the server will try to render the value inside the textbox, it will find it as readonly so it will not be able to set the value.

Also the value will never be "null" but an empty string.

Try setting this property upon PagePreRender rather than in aspx to delay the lockup on textbox. It will still be rendered as readonly for the end user, just that server will get a chance to put the value upon postback