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| Strauss, Jon (VIP) |
Hi,
I've created a composite server control that includes a textbox and a validator. However, I can't figure out how to access the textbox value from client-side javascript. The problem seems to be that the client id that get's generated doesn't match the id that I use when I declare my server control in my aspx page. So, when I try to access the control in javascript, I get "object is null or not an object". I also tried just deriving my control from the System.Web.UI.WebControls.TextBox, but I couldn't figure out a way to add a validator (without manually adding the equivalent javascript which seemed to defeat the purpose of using server controls).
I guess my question boils down to this:
*** Is there any way to access the value of one of the controls in a composite server control on the client-side? ***
Since I can do this with a TextBox server control (<asp:TextBox />), I figure there must be a way to do it with a composite control that contains a textbox. I just can't figure out how.
Any help would be greatly appreciated!
Thanks,
Jon
Here's some sample code of what I'm essentially trying to do...
.aspx page:
<%@ Register TagPrefix="Util" Namespace="MyControlLib" Assembly="MyControlLib" %>
<html>
<head>
<script language=javascript>
function TestAccess()
{
//this get's called, but displays "MyForm.cCompCtrl.value is null or not an object"
alert(MyForm.cCompCtrl.value);
}
</script>
</head>
<body MS_POSITIONING="GridLayout">
<form id="MyForm" method="post" runat="server">
<Util:TextCompControl runat=server id=cCompCtrl
onchange="javascript:TestAccess();" />
</form>
</body>
</html>
And here's my control:
using System;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace MyControlLib
{
/// <summary>
/// Summary description for TextCompControl.
/// </summary>
[ValidationPropertyAttribute("Text")]
public class TextCompControl: WebControl, INamingContainer
{
private TextBox m_TextBox = new TextBox();
private string m_OnChangeFunc;
public TextCompControl()
{
m_OnChangeFunc = null;
}
public string onchange
{
set
{
m_OnChangeFunc = value;
}
}
public string Text
{
get
{
return m_TextBox.Text;
}
set
{
m_TextBox.Text = value;
}
}
protected override void CreateChildControls()
{
m_TextBox.ID = this.ClientID;
if (m_OnChangeFunc != null)
m_TextBox.Attributes["onchange"] = m_OnChangeFunc;
this.Controls.Add(m_TextBox);
CustomValidator cv = new CustomValidator();
cv.ClientValidationFunction = "CheckVal";
cv.ControlToValidate = m_TextBox.ID;
cv.Display = ValidatorDisplay.Static;
cv.ErrorMessage = "Invalid value";
this.Controls.Add(cv);
}
}
}
|
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| |
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| Andy Smith |
The id of an inner control will concatenated with the id of the =
containing control.
This is so you won't get naming conflicts when multiple composite =
controls are placed on the form.
If you give your inner Textbox an ID, then the clientside id attribute =
will be CompositeControlID:TextBoxControlID. However, the name attribute =
will be CompositeControlID_TextBoxControlID.
( I may have those backwards, whatever, you'll see )
many times, control designers don't give the inner control ids, so the =
framework just makes one up.
If you give your control an ID, I don't think it'll be too hard to =
access it from client script.
__
Andy Smith
Chief Code Monkey
-----Original Message-----
From: Strauss, Jon [mailto:Click here to reveal e-mail address]
Sent: Friday, May 31, 2002 10:32 AM
To: aspngcontrolscs
Subject: [aspngcontrolscs] Accessing Server Control Value from
Client-Side
Hi,
I've created a composite server control that includes a textbox and a =
validator. However, I can't figure out how to access the textbox value =
from client-side javascript. The problem seems to be that the client id =
that get's generated doesn't match the id that I use when I declare my =
server control in my aspx page. So, when I try to access the control in =
javascript, I get "object is null or not an object". I also tried just =
deriving my control from the System.Web.UI.WebControls.TextBox, but I =
couldn't figure out a way to add a validator (without manually adding =
the equivalent javascript which seemed to defeat the purpose of using =
server controls). =20
I guess my question boils down to this: =20
*** Is there any way to access the value of one of the controls in a =
composite server control on the client-side? ***
Since I can do this with a TextBox server control (<asp:TextBox />), I =
figure there must be a way to do it with a composite control that =
contains a textbox. I just can't figure out how.
Any help would be greatly appreciated!
Thanks,
Jon
Here's some sample code of what I'm essentially trying to do...
.aspx page:
<%@ Register TagPrefix=3D"Util" Namespace=3D"MyControlLib" =
Assembly=3D"MyControlLib" %>
<html>
<head>
<script language=3Djavascript>
function TestAccess()
{
//this get's called, but displays "MyForm.cCompCtrl.value is null or =
not an object"
alert(MyForm.cCompCtrl.value);
}
</script>
</head>
<body MS_POSITIONING=3D"GridLayout">
=09
<form id=3D"MyForm" method=3D"post" runat=3D"server">
=09
<Util:TextCompControl runat=3Dserver id=3DcCompCtrl=20
onchange=3D"javascript:TestAccess();" />
</form>
=09
</body>
</html>
And here's my control:
using System;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace MyControlLib
{
/// <summary>
/// Summary description for TextCompControl.
/// </summary>
[ValidationPropertyAttribute("Text")]
public class TextCompControl: WebControl, INamingContainer
{
private TextBox m_TextBox =3D new TextBox();
private string m_OnChangeFunc;
public TextCompControl()
{
m_OnChangeFunc =3D null;
}
public string onchange
{
set
{
m_OnChangeFunc =3D value;
}
}
public string Text
{
get
{
return m_TextBox.Text;
}
set
{
m_TextBox.Text =3D value;
}
}
protected override void CreateChildControls()=20
{
m_TextBox.ID =3D this.ClientID;
if (m_OnChangeFunc !=3D null)
m_TextBox.Attributes["onchange"] =3D m_OnChangeFunc;
this.Controls.Add(m_TextBox);
CustomValidator cv =3D new CustomValidator();
cv.ClientValidationFunction =3D "CheckVal";
cv.ControlToValidate =3D m_TextBox.ID;
cv.Display =3D ValidatorDisplay.Static;
cv.ErrorMessage =3D "Invalid value";
this.Controls.Add(cv);
=09
}
}
}
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