Can't change the Visible property of a control in ASP.NET Web Forms?

By · March 23, 2015 · 0 comments

If you come across a problem where you set the Visible property of an ASP.NET control to true in a code behind file, but even when you debug it still shows the value as being false then the problem is most likely to be that the control is inside another control such as a Panel or PlaceHolder that has its Visible property set to false.

It appears that the Visible property can be a little confusing. It has certainly tripped me up more than once.

When a value is set for this property it will be remembered. So if you set Visible to true or false for a control that is within another control that is set to not be visible, if you later set that container control to be visible the control within it will then be visible or not visible depending on what value you set.

However, when you get the value for the Visible property, you are actually getting the current visibility of the control, and if a container control is not visible then of course the control within will also not be visible, no matter whether you have set it to visible or not.

To avoid problems it is best not to use the Visible property for certain conditional logic. Please see the example below for what not to do and how to do it correctly.

Incorrect:

btnSubmit.Visible = someValue == 1;
If (btnSubmit.Visible)
{
//some code here
}

Correct:

btnSubmit.Visible = someValue == 1;
If (someValue == 1)
{
//some code here
}
Read more...
ASP.NET Web Forms

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John Avis ...mostly about web development and programming, with a little bit of anything else related to the Internet, computers and technology.

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