How to use ASP.NET <%= tags in server control attributes?

This works:

<span value="<%= this.Text %>" />

This doesn’t work:
<asp:Label Text="<%= this.Text %>" runat="server" />

Why is that?

How can I make the second case work properly, i.e., set the label’s text to the value of the “Text” variable?

Answers:

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Method 1

Use Data binding expressions

<asp:Label ID="Label1" runat="server" Text="<%# DateTime.Now %>" ></asp:Label>

Code behind,
protected void Page_Load(object sender, EventArgs e){
  DataBind();
}

Method 2

you can do this

 <asp:Label ID="Label1" runat="server" ><%= variable%></asp:Label>

Method 3

You will need to set the value of the server control in code

First of all, assign an ID to the label control so you can access the control

<asp:Label ID="myLabel" runat="server" />

Then, in your Page_Load function, set the value of your labels ‘Text’ field
protected void Page_Load(object sender, EventArgs e)
{
    myLabel.Text = 'Whatever you want the label to display';
}

This function will be in your code behind file, or, if you are not using the code behind model, inside your aspx page you will need
<script runat="server">
    protected void Page_Load(object sender, EventArgs e)
    {
        myLabel.Text = 'Whatever you want the label to display';
    }
</script>

Good luck.

Method 4

In my code i am using something like this easily but in the databound control like ListView Item template

 <asp:HyperLink ID="EditAction" class="actionLinks" Visible='<%#Eval("IsTrue").ToString() != "True"%>' runat="server" NavigateUrl='<%# Eval("ContentId","/articles/edit.aspx?articleid={0}")%>' />

But when i tried to use outside the databound control using <%# .. %>, it simply doesn’t work.

You can easily do with

<a href="<%=myHref%>" rel="nofollow noreferrer noopener">My href</a>

But for server controls, and outside of databound control. We need to call DataBind() in pageload event explicitly
<asp:Hyperlink ID="aa" NavigateUrl='<%#myHref%>' >

Method 5

Not sure how to mark this as such, but this is a bit of a duplicate. See this thread.

I don’t think embedding code in to your markup will really make your markup any clearer or more elegant.

Method 6

<asp:Label> is compiling at runtime and converting to html tags. You can set text with codebehind or like this:

<asp:Label id="Text1" runat="server" />
<% Text1.Text = this.Text;%>

UPD: Seems like my variant doesnt work, this is better:
protected void Page_Load(object sender,EventArgs e) 
{
    Text1.Text = this.Text;
}

Method 7

Just pitching this little nugget in for those who want a good technical breakdown of the issue — https://blogs.msdn.microsoft.com/dancre/2007/02/13/the-difference-between-and-in-asp-net/

I think the crux is in pretty decent agreement with the other answers:

  • The <%= expressions are evaluated at render time
  • The <%# expressions are evaluated at DataBind() time and are not evaluated at all if DataBind() is not called.
  • <%# expressions can be used as properties in server-side controls. <%= expressions cannot.


All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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