I have a div and I am trying to add a CSS class to it in code but I receive the following error when I try
Property or indexer 'System.Web.UI.HtmlControls.HtmlControl.Style' cannot be assigned to -- it is read only
I am using the following code:
protected void BTNEvent_Click(object sender, ImageClickEventArgs e)
{
BtnventCss.Style= "hom_but_a";
}
Can anyone please help me?
What if:
<asp:Button ID="Button1" runat="server" CssClass="test1 test3 test-test" />
To add or remove a class, instead of overwriting all classes with
BtnventCss.CssClass = "hom_but_a"
keep the HTML correct:
string classname = "TestClass";
// Add a class
BtnventCss.CssClass = String.Join(" ", Button1
.CssClass
.Split(' ')
.Except(new string[]{"",classname})
.Concat(new string[]{classname})
.ToArray()
);
// Remove a class
BtnventCss.CssClass = String.Join(" ", Button1
.CssClass
.Split(' ')
.Except(new string[]{"",classname})
.ToArray()
);
This assures
Especially when client-side development is using several classnames on one element.
In your example, use
string classname = "TestClass";
// Add a class
Button1.Attributes.Add("class", String.Join(" ", Button1
.Attributes["class"]
.Split(' ')
.Except(new string[]{"",classname})
.Concat(new string[]{classname})
.ToArray()
));
// Remove a class
Button1.Attributes.Add("class", String.Join(" ", Button1
.Attributes["class"]
.Split(' ')
.Except(new string[]{"",classname})
.ToArray()
));
You should wrap this in a method/property ;)
<div runat="server"> is mapped to a HtmlGenericControl.
Try using:
BtnventCss.Attributes.Add("class", "hom_but_a");
For a non ASP.NET control, i.e. HTML controls like div, table, td, tr, etc. you need to first make them a server control, assign an ID, and then assign a property from server code:
<head>
<style type="text/css">
.top_rounded
{
height: 75px;
width: 75px;
border: 2px solid;
border-radius: 5px;
-moz-border-radius: 5px; /* Firefox 3.6 and earlier */
border-color: #9c1c1f;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div runat="server" id="myDiv">This is my div</div>
</form>
</body>
myDiv.Attributes.Add("class", "top_rounded");
The Style property gets a collection of all the cascading style sheet (CSS) properties; you cannot set it.
Try BtnventCss.CssClass = "hom_but_a"; instead.
I'm assuming BtnventCss is a WebControl.
I have just seen you're probably using <div runat="server"...
If so, you can try:
BtnventCss.Attributes.Add("class", "hom_but_a");
You could make the div an asp:panel - they will render the same and you'll get better server-side support.
Here are two extension methods you can use. They ensure any existing classes are preserved and do not duplicate classes being added.
public static void RemoveCssClass(this WebControl control, String css) {
control.CssClass = String.Join(" ", control.CssClass.Split(' ').Where(x => x != css).ToArray());
}
public static void AddCssClass(this WebControl control, String css) {
control.RemoveCssClass(css);
css += " " + control.CssClass;
control.CssClass = css;
}
Usage: hlCreateNew.AddCssClass("disabled");
Usage: hlCreateNew.RemoveCssClass("disabled");
Button1.CssClass += " newClass";
This will not erase your original classes for that control. Try this, it should work.
To ADD classes to html elements see how to add css class to html generic control div?. There are answers similar to those given here but showing how to add classes to html elements.
I'm also looking for the same solution. And I think of
BtnventCss.CssClass = BtnventCss.CssClass + " hom_but_a";
It seems working fine but I'm not sure if it is a good practice
