i was trying to hide and show a button using following code
where AllowUpdate is a property of page.
now problem is This statement never get Executed.
I have used similar code on other pages but it is unreliable many times it just fails and hides buttons even if they must not be
<asp:Button runat="server" ValidationGroup="param" Text='<%$ Resources:Resources, Save%>' ID="btnsave" CssClass="btn btn-primary btn_round" OnClick="btnsave_Click" Visible="<%# AllowUpdate %>" />
If you're going to use the <%# %> syntax, you must call data bind.
<asp:Panel runat="server" ID="Panel1">
<%# SomeProperty %>
</asp:Panel>
Code behind:
Panel1.DataBind();
Alternatively, use the <%= %> syntax.
<%= SomeProperty %>
or as Cal279 points out in the comments, you can set it in your code behind on some event, such as Page_Load.
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
Butbtnsaveon1.Visible = AllowUpdate;
}
}
Related
I want to set CSS class to asp:Button control using Session value. I have tried this, but it does not works.
<asp:Button ID="btnSave" runat="server" Text="<%$ Resources:Application,Save %>" CssClass="<%# Common.SessionInfo.Button %>" ValidationGroup="save"
OnClick="btnSave_Click" />
It works fine, when I set it from code behind
btnSave.CssClass = Common.SessionInfo.Button;
Please help...
You need to call DataBind method from code behind as in code below. When you use expression like <%# %> then you need to call databind on that server control in your code-behind.
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
this.btnSave.DataBind();
}
}
You may create method in your code behind:
public string GetButtonClass(){
return Session["your_key"].ToString();
}
and call this method to your button:
<asp:Button ID="btnSave" runat="server" Text="<%$ Resources:Application,Save %>" CssClass="<%=GetButtonClass()%>" ValidationGroup="save"
OnClick="btnSave_Click" />
I have a simple ListView with an EmptyDataTemplate. In the EmptyDataTemplate, there is a LinkButton whose Visble property value is an expression that calls a method in my code behind. The problem is that the LinkButton is always visible regardless of whether the method returns true or false (my method isn't being called as I even set a breakpoint on it). Anyone come across this? What's happening here?
e.g.
<asp:ListView ID="peopleListView" runat="server" ...>
...
<EmptyDataTemplate>
Sorry, no people to view.<br />
<asp:LinkButton ID="newButton" runat="server" Visible='<%# EditPermitted() %>'>New Record</asp:LinkButton>
</EmptyDataTemplate>
</asp:ListView>
In the code behind, I have the method:
protected bool EditPermitted()
{
return false;
}
I don't think you can put scriplets <% %> inside of server controls.
You need to grab the RowDataBound event, and set the link button's visibility there
void gridView1_RowDataBound(object sender, GridViewRowEventArgs e) {
if (e.Row.RowType == DataControlRowType.EmptyDataRow) {
LinkButton lb = e.Row.FindControl("newButton");
lb.Visible = EditPErmitted();
}
}
You can't use code blocks like <% ... %> or <%= ... %> inside the attributes of server controls. Only data binding blocks like <%# ... %>. But you can use code blocks inside your EmptyDataTemplate, in this case a simple if statement should work:
<EmptyDataTemplate>
<% if(EditPermitted()) { %>
<asp:LinkButton ID="newButton" runat="server" ... />
<% } %>
</EmptyDataTemplate>
I have a case that I need to set the Text property for an asp label in the aspx page not from code behind. More exactly, I need to set a value to asp control in aspx page and this value is set by a property in the same page code behind.
so I need to use an expression to do that like:
<asp:Label Text="<%= MyProperty %>" ..../>
I use:
<%= MyProperty %> doesn't work.
<%# MyProperty %> doesn't also.
Default.aspx.cs
public partial class _Default : System.Web.UI.Page
{
public string CustomTitle = "This Is Title";
protected void Page_Load(object sender, EventArgs e)
{
Page.DataBind();
}
}
Default.aspx
<asp:Label Text='<%#CustomTitle %>' runat="server" />
You have to treat regular HTML and WebControls differently:
regular HTML:
Using <%= ... %> is sufficient:
<span><%= MyProperty %></span>
WebControls (stuff starting with <asp:...>):
<asp:Label Text='<%# MyProperty %>' />
In this case, you also have to call Me.DataBind() (VB) or this.DataBind(); (C#) in your codebehind, since <%# ... %> are data binding expressions.
Page.DataBind();
Do you call this in your code? It binds all variables set in code to your page.
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?
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();
}
you can do this
<asp:Label ID="Label1" runat="server" ><%= variable%></asp:Label>
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.
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
My href
But for server controls, and outside of databound control. We need to call DataBind() in pageload event explicitly
<asp:Hyperlink ID="aa" NavigateUrl='<%#myHref%>' >
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.
<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;
}
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.
I am trying to hide the button based on the user's role using the following code:
<asp:Button ID="btndisplayrole" Text="Admin Button" Visible='<%= WebApplication1.SiteHelper.IsUserInRole("Admin") %>' runat="server" OnClick="DisplayRoleClick" />
But when I run the above code I get the following error message:
Cannot create an object of type 'System.Boolean' from its string representation '<%= WebApplication1.SiteHelper.IsUserInRole("Admin") %>' for the 'Visible'
Kind of an interesting issue.. But as the error message states, the string <%= WebApplication1.SiteHelper.IsUserInRole("Admin") %> cannot be converted to a boolean.
Unfortunately i cannot explain why the expression isn't evaluated, but instead is treated like a string.
The reason why your <%# %> expression works as expected, is because it is treated much differently. When the Page is compiled into a class, then the compiler creates an event handler similar to this:
public void __DataBindingButton2(object sender, EventArgs e)
{
Button button = (Button) sender;
Page bindingContainer = (Page) button.BindingContainer;
button.Visible = HttpContext.Current.User.IsInRole("admin");
}
and hooks this method up to the Control.Databinding event on your control. As you can see, the <%# %> is this time properly treated as server code, and not just a random string.
So i guess the solution is either to use databinding, or go to the codebehind as AndreasKnudsen suggests.
As an alternative solution:
<% if (WebApplication1.SiteHelper.IsUserInRole("Admin"))
{%>
<asp:Button ID="btndisplayrole"
Text="Admin Button"
runat="server"
OnClick="DisplayRoleClick" />
<%} %>
The following code worked:
Visible='<%# WebApplication1.SiteHelper.IsUserInRole("Admin") %>'
Note that the aboe use the binding expression!
how about just doing it in the codebehind, for instance on Page_Load ?
public void Page_Load( object sender, EventArgs e )
{
btndisplayrole.Visible = WebApplication1.SiteHelper.IsUserInRole("Admin");
}
Visible='<%= WebApplication1.SiteHelper.IsUserInRole("Admin").ToString() %>'
OR
Visible=<%= WebApplication1.SiteHelper.IsUserInRole("Admin") %>