BackColor binding does not work on postback

[Dmitry Duginov]

Hi,

I have the following label markup (label is inside FormView):

<asp:Label
ID="lblIndicatorReady" runat="server" Text="RE" ToolTip="Ready"
BackColor='<%#
Eval("Ready").ToString()=="True"?System.Drawing.Color.FromName("#FFFF80"):System.Drawing.Color.White
%>'
Enabled='<%# Eval("Ready") %>'
Font-Bold='<%# Eval("Ready") %>'>
</asp:Label>

I.e. late binding for the "Ready" property used to determine should the
label be
(bold, highighted and enabled) or (plain, white background, disabled)

On initial load everything works as expected (for ready items label is
colored). But on postbacks BackColor is always white for some reason.
Enabled and Bold properties are shown correctly though.

Any ideas?

Dmitry.

 

[Steven Cheng[MSFT]]

Hi Dmitry,

As for the ASP.NET Label DataBinding backColor color problem, I have also
performed some tests on my side and did repro the same behavior. Actually,
here is something else I also got:

The problem is not specific to FormView but seems a binding issue of the
Label control. I can get this behavior even through the following simple
routine:

** put a Label on the top level of aspx form
** and use a page variable to perform databinding against the Label control
** After click another posback button, the previous bound color
lost(Forecolor property also suffers this problem)

Currently I'll do some further research on this and will update you if
there is any new finding or information.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead



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--------------------

 

[Dmitry Duginov]

Hi, Steven!

Anything new? Workarounds, suggestions?

Dmitry

 

[Steven Cheng[MSFT]]

Thanks for your followup Dmitry,

I'm still contacting some other ASP.NET engineers on this issue so as to
definitely confirm this issue.

For workarounds, currently what I have got is a possible means through
programmrtically update the TextBox's Color property through "PreRender"
event. The "PreRender" event is the latest event before the control being
rendered. Therefore, you can register this event for the textbox and detect
its value(through Text property) and programmaticlaly set its BackColor(or
other decorate properties...) at that time. e.g.

==============
protected void TextBox1_PreRender(object sender, EventArgs e)
{
TextBox txt = sender as TextBox;

if (txt.Text == ".....")
{
txt.BackColor = Color.Yellow;
}
else
{
txt.BackColor = Color.Maroon;
}
}
==============

In addition, by some futher testing, in some C# web site projects, I found
the problem is not always reproable. Therefore, I also suggest you to test
it in different projects and pages(you can use TextBox on page's top level
or inside a FormView). It would be helpful that if you can give me a
definite steps that can constantly repro the behavior.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead


This posting is provided "AS IS" with no warranties, and confers no rights.

--------------------

 

[Dmitry Duginov]

Thanks for your followup Dmitry,

I'm still contacting some other ASP.NET engineers on this issue so as to
definitely confirm this issue.

For workarounds, currently what I have got is a possible means through
programmrtically update the TextBox's Color property through "PreRender"
event. The "PreRender" event is the latest event before the control being
rendered. Therefore, you can register this event for the textbox and
detect
its value(through Text property) and programmaticlaly set its BackColor(or
other decorate properties...) at that time. e.g.

Sorry, Steven, but

- the issue is with the Label control, not a textbox
- highlighting has nothing to do with the value of its Text property, it is
bound to the property of a business object

Regards,
Dmitry

 

[Steven Cheng[MSFT]]

Hi Dmitry,

Sorry for keep you waiting.

After some further research, I got the cause of the problem. It is actually
caused by the "Color.FromName" function you used. In your original code,
you use it as below:

System.Drawing.Color.FromName("#FFFF80")

this is actually an incorrect and unsupported usage. Refer to the document
below:

#Color.FromName Method
http://msdn2.microsoft.com/en-us/library/system.drawing.color.fromname.aspx
Parameters
name
A string that is the name of a predefined color. Valid names are the same
as the names of the elements of the KnownColor enumeration.
<<<<<<<<<<<<<

Therefore, if you use the "#XXXXXX" like color, it will cause the problem
when serializing the viewstate. The color is unknown to the serializer and
it store the blank color into the view state(that's why you see the color
lost on postback). One quick resolution here(if you do need to specify the
"#xxxxxx" like html color instead of a known color name or RGB value, you
can use the ColorTranslator.FromHtml() method instead. e.g.

==================
<asp:Label ID="Label1" runat="server" Text="Label"
BackColor='<%#
TestBool.ToString()=="True"?System.Drawing.ColorTranslator.FromHtml("#FFFF80
") ystem.Drawing.Color.White %>' ........./>

==================

I've tested it and it works. Hope this helps.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead


This posting is provided "AS IS" with no warranties, and confers no rights.


--------------------

From: "Dmitry Duginov" <[email protected]>
Subject: Re: BackColor binding does not work on postback
Date: Thu, 4 Oct 2007 19:56:54 -0400

Thanks for your followup Dmitry,

I'm still contacting some other ASP.NET engineers on this issue so as to
definitely confirm this issue.

For workarounds, currently what I have got is a possible means through
programmrtically update the TextBox's Color property through "PreRender"
event. The "PreRender" event is the latest event before the control being
rendered. Therefore, you can register this event for the textbox and
detect
its value(through Text property) and programmaticlaly set its BackColor(or
other decorate properties...) at that time. e.g.

Sorry, Steven, but

- the issue is with the Label control, not a textbox
- highlighting has nothing to do with the value of its Text property, it is
bound to the property of a business object

Regards,
Dmitry

 

[Dmitry Duginov]

Hi Dmitry,

Sorry for keep you waiting.

After some further research, I got the cause of the problem. It is
actually
caused by the "Color.FromName" function you used. In your original code,
you use it as below:

System.Drawing.Color.FromName("#FFFF80")

lost on postback). One quick resolution here(if you do need to specify the
"#xxxxxx" like html color instead of a known color name or RGB value, you
can use the ColorTranslator.FromHtml() method instead. e.g.

Thank you! It resolved the issue.

Dmitry.

 

[Steven Cheng[MSFT]]

You're welcome!

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead


This posting is provided "AS IS" with no warranties, and confers no rights.
--------------------

From: "Dmitry Duginov" <[email protected]>
References: <#[email protected]>

Subject: Re: BackColor binding does not work on postback
Date: Tue, 9 Oct 2007 17:00:56 -0400