Custom Control ClientID weirdness

  • Thread starter Thread starter Olorin
  • Start date Start date
O

Olorin

I'm encountering some weird behavior with the ClientID property. Let's
see if I can give you enough info and if anyone has ideas/suggestions.

I'm working in ASP.NET 2.0. I have a Web Project with a master page,
with a single ContentPlaceholder on it.
I have a page that uses that Master template, and is meant to place 2
controls of type Fred in the content placeholder. The .aspx for this
page goes like this:
[register tag prefix cc to grab custom controls from a separate
project]
....
<asp:Content ID="Content1"
ContentPlaceHolderID="contentPlaceholder_Workarea" runat="server">
<cc:Fred runat="Server" ID="fred_1" />
<cc:Fred runat="Server" ID="fred_2"></cc:Fred>
</asp:Content>

The Fred control is actually a custom control I defined as inheriting
from CompositeControl. Fred overrides TagKey to return
HtmlTextWriterTag.Div. It also overrides CreateChild Control to do a
few things, among which, it adds a System.Web.UI.WebControls.Panel
named Wilma to its Controls. When I add a Wilma to the controls, I add
an attribute to it like this:
myWilma.Attributes.Add("onclick", "alert('"+this.ClientID+"');");

It all works quite nicely, and the Wilma's have the Freds' mangled Ids
(e.g.: onclick="alert('ctl00_contentPlaceholder_Workarea_fred_1')")
available.

However, if I put anything (and I mean anything, even a space
character, a newline character, ...) between the opening and closing
tags of a Fred control, like this:
<cc:Fred runat="Server" ID="fred_2"> </cc:Fred>
Then Wilma's onclick event gets an un-mangled version of Fred's ID
(e.g.: onclick="alert('fred_2');" ).

It seems that I'm missing some crucial step/aspect that makes my
controls' Client IDs go out of sync.
I have checked fred_2's ClientID from the surrounding page Page_Load
method, and it is mangled at that time.
So, the difference is between the times when Page_Load and the
control's CreateChildControls methods run...

Any suggestion ?

Thanks in advance,
Frank
 
I'm encountering some weird behavior with the ClientID property. Let's
see if I can give you enough info and if anyone has ideas/suggestions.

I'm working in ASP.NET 2.0. I have a Web Project with a master page,
with a single ContentPlaceholder on it.
I have a page that uses that Master template, and is meant to place 2
controls of type Fred in the content placeholder. The .aspx for this
page goes like this:
[register tag prefix cc to grab custom controls from a separate
project]
...
<asp:Content ID="Content1"
ContentPlaceHolderID="contentPlaceholder_Workarea" runat="server">
<cc:Fred runat="Server" ID="fred_1" />
<cc:Fred runat="Server" ID="fred_2"></cc:Fred>
</asp:Content>

The Fred control is actually a custom control I defined as inheriting
from CompositeControl. Fred overrides TagKey to return
HtmlTextWriterTag.Div. It also overrides CreateChild Control to do a
few things, among which, it adds a System.Web.UI.WebControls.Panel
named Wilma to its Controls. When I add a Wilma to the controls, I add
an attribute to it like this:
myWilma.Attributes.Add("onclick", "alert('"+this.ClientID+"');");

It all works quite nicely, and the Wilma's have the Freds' mangled Ids
(e.g.: onclick="alert('ctl00_contentPlaceholder_Workarea_fred_1')")
available.

However, if I put anything (and I mean anything, even a space
character, a newline character, ...) between the opening and closing
tags of a Fred control, like this:
<cc:Fred runat="Server" ID="fred_2"> </cc:Fred>
Then Wilma's onclick event gets an un-mangled version of Fred's ID
(e.g.: onclick="alert('fred_2');" ).

It seems that I'm missing some crucial step/aspect that makes my
controls' Client IDs go out of sync.
I have checked fred_2's ClientID from the surrounding page Page_Load
method, and it is mangled at that time.
So, the difference is between the times when Page_Load and the
control's CreateChildControls methods run...

Any suggestion ?

Thanks in advance,
Frank
Click to expand...

Hi,

A asp,net controls client id is generated according to where the
control reside...
i.e. if i add the control in a panel and then add the panel in
usercontrol and at last in page
client id will be usercontrolclientid+panelclientid
+controlclientid.....
if i change my control from one panel to another panel it will change
accordingly...
so its better to generate any script in onrender method of control
life cycle...

Thanks
Masudur
 
so its better to generate any script in onrender method of control
life cycle...

Thanks
Masudur
Click to expand...
Thanks, Masudur, your hint helped me out and I was able to make the
Freds and Wilmas work out as intended.
I was assuming that the Render method in CompositeControl would call
the CreateChildControls method (which I was overriding), but it turns
out that's not the case.

Thanks again,
~O.
 
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