I'm trying to find a linkbutton inside on my aspx page.
I don't want to find the originator, like the specific sender, I just want to find the overall linkbutton in the itemtemplate and make them all invisible.
Here is the ASPX code where the linkbutton is
<ItemTemplate>
<table>
<tr>
<td>
<asp:TextBox ID="DisplayOP" runat="server" Text="test" Visible="false"></asp:TextBox>
</td>
</tr>
<tr>
<td><asp:Linkbutton ID="ItemEmneLabel" runat="server" Text='<%# Eval("Emne") %>' OnClick="ItemShowComments" CommandArgument='<%# Eval("OpslagsID") %>' Visible="true" /></td>
<--- Code Omitted --->
In my code behind .cs file I try to find it like this:
var lnkb = (LinkButton)ListView1.FindControl("ItemEmneLabel");
lnkb.Visible = false;
and this:
var lnkb = (LinkButton)this.ListView1.FindControl("ItemEmneLabel");
lnkb.Visible = false;
However whatever I try I get an error saying:
{"Object reference not set to an instance of an object."}
What am I doing wrong here?
it's impossible to find a control declared in an ItemTemplate like this.
You can only get the control with sender in ItemShowComments method.
Okay, so I found the solution to my problem.
Now I wanted to disable the visibility of the linkbuttons, when the listview was showing specific data. I kept looking for the answer in code behind, but found out that I could solve it in aspx.
What I did was add a statement to visibility like this:
Visible='<%# !Eval("Emne").Equals("") %>'
The exclamationmark (!) in front of Eval means, if it is NOT equal to "". This means that if "Emne" is not-empty, then the statement is true, thus visible is true. I could do it the other way around by coding it like this:
Visible='<%# Eval("Emne").Equals("") %>'
Related
Noob question.
Why does this not work into my .aspx file?
<body>
<asp:Label ID="Label1" runat="server" Text='<%=System.DateTime.Today.Day.ToString()%>' ></asp:Label>
</body>
It does display the <%=System.DateTime.Today.Day.ToString()%> string which is obviously not what I want.
Same result if I try to display the content of a code behind variable:
<asp:Label ID="label" runat="server" Text='<%= versionNumber %>' >
versionNumber being properly instanced and set into the code behind.
You cannot mix server controls with code blocks.
There are two ways to work around that limitation:
Just use <%=System.DateTime.Today.Day.ToString()%> without a Label around it
Use codebehind to set Label1.Text = System.DateTime.Today.Day.ToString();
The first way will display the date to the user, but you cannot further change it from codebehind.
The second way does enable you to alter the text from codebehind.
It is true you can't mix server controls with Code blocks,
If its compulsory for you to use Server side control, and you don't even want to set value from code behind then you can go for this solution.
<asp:Label ID="Label1" runat="server"><%=System.DateTime.Today.Day.ToString() %></asp:Label>
Similarly you can use code behind variable as follows ,
<asp:Label ID="Label1" runat="server"><%=versionNumber %></asp:Label>
If you really want to use a asp:Label
Use it as follows:
<asp:Label ID="Label1" runat="server"><%=System.DateTime.Today.Day.ToString() %></asp:Label>
Hello and thanks for taking your time to help me.
I'm trying to change the text of a textbox thats located inside my repeater.
<asp:Repeater runat="server" ID="rpCategories">
<HeaderTemplate>
<ul id="nav_down" class="nav_down">
</HeaderTemplate>
<ItemTemplate>
<li><%# Eval("Title") %></li>
</ItemTemplate>
<FooterTemplate>
<li></li>
<li>Contact</li>
<li><a id="cart_logo"></a>
<asp:Panel runat="server" ID="pnlBasket">
<asp:textbox runat="server" id="txtTotalCount" Enabled="false" CssClass="ltTotalCount"></asp:textbox>
</asp:Panel>
</li>
</ul>
</FooterTemplate>
</asp:Repeater>
It's the asp:textbox with the id="txtTotalCount" that I want to change the text of.
Here is my C# code:
TextBox ltTotalCount = (TextBox)FindControl("lblTotalCount");
ltTotalCount.Text = "1";
But if I run the code I get this error : Object reference not set to an instance of an object.
Would be so happy if someone could tell me what I'm doing wrong.
Becuase lblTotalCount is inside a parent control - the repeater, you have to reference it through the repeater.
You should be able to just add the id of your repeater before FindControl, like this...
TextBox ltTotalCount = (TextBox)rpCategories.FindControl("lblTotalCount");
You have to specify the repeater as the parent control to look for the text box and also since it's repeater its quite possible to have more than one text box with that Id so you have to specify which repeater item to look into like so:
TextBox ltTotalCount = rpCategories.Items[0].FindControl("txtTotalCount") as TextBox;
This will return the textbox in the first row of the repeater.
And you should use the Id value not the CssClass value
The ID is probably being 'enhanced' to prevent duplicate IDs in the rendered HTML. You can verify this by looking at the html.
You can add this to the textbox: ClientIDMode="Static" to make the ID stay the same.
You are getting the error because FindControl is returning a null but you are trying to access it anyway.
[Edit] Someone pointed out that this shouldn't work. I agree, here is what does work:
Control FooterTemplate = rpCategories.Controls[rpCategories.Controls.Count - 1].Controls[0];
TextBox MyTextBox = FooterTemplate.FindControl("txtTotalCount") as TextBox;
Is it possible to programatically insert C# Inline Expressions as the values for ASP.NET Controls in your server-side code?
I'm currently using a DataList to display a lot of data in a table. I want to be able to dynamically change the columns of that table, so I need to be able to edit what controls are in its ItemTemplate.
However, in addition to editing the controls in the ItemTemplate, I need to be able to alter the value that is binded to each control in the template, because I want to dynamically change what is being displayed.
So what I currently have is a static table that doesn't change:
<asp:DataList ID="dataList" runat="server" OnSelectedIndexChanged="dataList_OnSelectedIndexChanged" DataSourceID="peopleData">
<ItemTemplate>
<table>
<tr>
<td>
<asp:LinkButton ID="NameLink" OnClientClick="onPageUpdate()" CommandName="Select" Text='<%# Eval(this.Name) %>' ForeColor='<%# Eval("this.NameColor") %>' runat=Server" />
</td>
<td>
<asp:Label Text='<%# Eval("this.Values[\"Age\"]") %>' ForeColor='<%# Eval("this.ValueColors[\"Age\"]") %>' runat="Server">
</td>
// OTHER COLUMNS WITH DIFFERENT DATA
</tr>
</table>
</ItemTemplate>
</asp:DataList>
// OBJECT DATA SOURCE CODE
I know how to dynamically add Controls to the ASPX web page. However, I don't know how to add the inline expressions.
I've tried doing the following but it doesn't work because of the type mismatches:
Label label = new Label();
label.Text = "<%# Eval(\"this.Values[\\\"Age\\\"]\") %>";
label.ForeColor = "<%# Eval(\"this.ValueColors[\\\"Age\\\"]\") %>";
Is there a way of achieving this or doing something similar?
My only other option that I can think of right now is to scrap using the DataList and ItemTemplate and just generate each row myself.. That's a lot more coding versus just using the ItemTemplate.
Not sure if this would help you, but look at http://msdn.microsoft.com/en-us/library/system.web.ui.databinder(v=vs.100).aspx
It is showing using of the hand-written exposure of properties. If your property were always call "magic" and you return the appropriate value for magic within your code would that get you what you need?
Here is an example. The problem is that the Label2 has always Visible=true, regardless of the if-else result. How can i know if its visible or not?
<asp:GridView runat="server" ID="gdv">
<asp:TemplateField>
<ItemTemplate>
<%if (!IsItem)
{%>
<asp:TextBox runat="server" Text='<%# Eval("Qtde") %>'></asp:TextBox>
<%}
else
{ %>
<asp:Label ID="Label2" runat="server" Text='<%# Eval("Qtde") %>'></asp:Label>
<%} %>
</EditItemTemplate>
</asp:TemplateField>
I cannot access IsItem, since the class where i want to check the label for visibility is not the page code-behind. Also these controls are in a gridview.
The class method that checks for visibility is not called directly by the page, its a private method of a server control that extends a grid view and is supposed to work with a varierty of cases.
Thanks.
EDIT------------
I have found an alternative, decent solution. Still, i'm curious to know if it's possible to do the aforementioned. Thanks you for your time,
You are displaying that Label based on a variable called "IsItem." Why can't you use that to determine the Label's visibility?
Can somebody please explain this to me:
I have a label and I want to be able to set the Text property by calling a method in the aspx file. It works fine if I set the property in code behind, but I really want to set this property in the aspx file.
I have tried a couple of things, but what I expected to work was this:
<asp:Label ID="Label1" runat="server" Text=<%# GetMyText("LabelText") %> />
I get no errors when doing this, but my method is never called and the Text property is left empty.
Is it not possible to set property values to server side controls directly in the aspx without using resources or use hard coded values?
Update: My first try was:
<asp:Label ID="Label1" runat="server" Text=<%= GetMyText("LabelText") %> />
But that results in the following error:
Server tags cannot contain <% ... %> constructs.
The syntax =<%# ... %> is Data binding syntax used to bind values to control properties when the DataBind method is called.
You need to call DataBind - either Page.DataBind to bind all the controls on your page, or Label1.DataBind() to bind just the label. E.g. add the following to your Page_Load event handler:
if (!IsPostBack)
{
this.DataBind();
// ... or Label1.DataBind() if you only want to databind the label
}
Using Text='<%= GetMyText("LabelText") %>' as others have proposed won't work as you'll find out. This syntax is inherited from classic ASP. It can be used in some circumstances in ASP.NET for inserting dynamic values in static HTML, but can not be used for setting propeties of server controls.
The sysntax you are looking for is <%= %> the # is for data binding. So your code should read:
<asp:Label ID="Label1" runat="server" Text='<%= GetMyText("LabelText") %>' />
EDIT: This answere is incrrect
I am leaving this answer here because lots of people agreed with me that this is infact the correct answer, but it will not work. This line of code will produce the following HTML output:
<span id="Label1"><%= GetMyText("LabelText") %></span>
Try this:
<asp:Label ID="Label1" runat="server" Text='<%= GetMyText("LabelText") %>' />
Edit
Yep. I was wrong. #Joe was right.
However, THIS works (and I'm not sure what the difference is):
<asp:Label ID="Label1" runat="server"><%= GetMyText("LabelText") %></asp:Label>
CodeBehind:
protected string GetMyText(string input)
{
return "Hello " + HttpUtility.HtmlEncode(input);
}