I am scratching my head over this, but have no idea what the problem is.
My actual code is
<asp:Label ID="Label1" runat="server" Text="abc"
Visible='<%#Request.QueryString["ListName"] == null %>' />
<asp:GridView ID="gvLists" runat="server"
Visible='<%#Request.QueryString["ListName"] == null %>' />
As you can see, i am trying to only make the visibility of the object be driven by the querystring. It works fine for the GridView, but doesn't work for a label. I also tried Panel and HyperLink with the same results.
I am sure I could get this working by putting my code in the code-behind, but it won't be as clean.
<%# %> works only on databound items.
you need to change it to <%= %> (Notice the "=")
<%= is uses to print to the page directly and the <%# is used for data binding elements. Here is a great explanation of all the inline code directives.
Thanks to Alison for pointing me in the right direction.
I needed to add Page.DataBind() to my Page_Load event in order for the expression to be evaluated.
Related
I have the following control in ASP.Net
<asp:Button ID="btnDownload" runat="server" Text="Run" CssClass="button" OnClientClick='Download( <%# Eval("ID") %> )' />
When I run the page, the following details are being outputted to the browser.
<input type="submit" name="gvMaster$ctl02$btnDownload" value="Run" onclick="DownloadReport( <%# Eval("ID") %> );" id="gvMaster_btnDownload_0" class="button" />
Why isn't the <%# Eval("ID") %> actually evaluating? To be clear, originally I had a small JS snippet within this statement. I had to make a minor modification, so I moved it to a JS method. After moving the code and leaving just the ID as a parameter, this result started showing up where, before, it was actually evaluating to the value in the associated record.
What could be going on? I've not seen this before.
Reposting comment as answer:
I don't think you can set properties on server side controls using data-binding like that (mixing static text and dynamic Eval values). You should use the OnItemDataBound event for the parent repeater/datagrid/etc and set it in the code behind, or use OnClientClick='<%# Eval("ID", "Download({0})") %>', where the entire value is evaluated and sent to the attribute all at once.
try OnClientClick='<%# "Download(" +Eval("ID") + " );" %>' i suspect you need the server code to evaluate the whole expression in javascript so when rendered by the browser it will correctly trigger the function.
Does anyone know what is wrong with the following two lines of code? In both cases, there is no href in the anchor links when i view it in the browser:
<asp:HyperLink runat="server" NavigateUrl='<%# Eval(Request.QueryString["conferenceId"], "~/Cms/schedule-edit.aspx?conferenceId={0}&type=workshopStream") %>' Text="Create Workshop Stream"></asp:HyperLink>
<asp:HyperLink runat="server" NavigateUrl='<%# String.Format("~/Cms/schedule-edit.aspx?conferenceId={0}&type=scheduleItem", Request.QueryString["conferenceId"]) %>' Text="Create Schedule Item"></asp:HyperLink>
This exact same code seems to work fine when I put it into the ItemTemplate of a Listview though. But it doesn't work when used on it's own in an aspx file.
What's wrong with it?
Also if i replace the navigateUrl with a hardcoded string ~/cms/schedule-edit.aspx?conferenceId=2&type=stuff then the href shows up. It just doesn't work when i have the Eval or String.Format in there.
If those HyperLink server controls are located outside of DataBound controls like GridView, there are two problems in our code -
You want to use <%= %> instead of <%# %> which is used in DataBound controls.
You cannot use <%= %> to set property of a server control. Basically, you cannot mix runat="server" with <%= %>.
Solution
<a href='<%= String.Format("~/Cms/schedule-edit.aspx?conferenceId={0}&type=scheduleItem",
Request.QueryString["conferenceId"]) %>'>Create Workshop Stream</a>
The anchor syntax NavigateUrl='<%#...%> is only valid inside a GridView, ListView, etc. When it is not inside such controls, you can set its NavigateUrl property via code. Obviously, you also need to give an ID to your HyperLink.
The markup:
<asp:HyperLink ID="HyperLink1" runat="server" Text="Create Schedule Item"></asp:HyperLink>
The code behind:
HyperLink1.NavigateUrl = String.Format("~/Cms/schedule-edit.aspx?conferenceId={0}&type=scheduleItem", Request.QueryString["conferenceId"])
You are using a data-binding expression here. This is denoted in the following syntax:
<%# [code] %>
The code inside is evaluated only when the containing control, or any of its ancestors have their .DataBind() method called.
To work this around, you can:
Call Page.DataBind()
This could have some unwanted consequences if you have other data-bound controls on the page, as this method will cause all of them to have their data-binding events fired. Usually, this approach is applied if you have minimalistic code-behind and the entire page relies on data-binding expressions.
Give each HyperLink an ID and call HyperLinkID.DataBind();
Stick to the approach in codingstill's answer by setting the NavigateUrl property in the code behind of your page/user control.
i'm in a asp.net listview, in the itemtemplate.
<asp:ListView runat="server" ClientIDMode="Predictable" ClientIDRowSuffix="Texttranslations_key"ID="lvwTextitems">
This is my code in the itemtemplate:
<span runat="server" onclick="openDiv('<%= EditItemDiv.ClientID%>')" style="width: 450px;"><%# Eval("Translation")%></span>
<asp:panel runat="server" id="EditItemDiv" style="display:none">
<asp:TextBox runat="server" ID = "EditItemArea" TextMode ="MultiLine" Rows="12" Columns="50" Text="<%# Eval("Translation")%>">
</asp:TextBox>
Now i have two problems.
First the span: i want the clientID of the asp:panel in the function openDiv(), so i can create some show hide functionality.
However, i get this as result:
<span onclick="openDiv('<%= EditItemDiv.ClientID%>')" style="width: 450px;">
my code isn't seen as code, but as plain text, and i don't know why?
Second, this line gets me a runtime error (The server tag is not well formed):
<asp:TextBox runat="server" ID = "EditItemArea" TextMode ="MultiLine" Rows="12" Columns="50" Text="<%# Eval("Translation")%>">
Can somebody help me out?
ps
at first i used this code for the generation of the id's: "myid<%# Eval("Id")%>" but that didn't workout either...
ps
i'm always getting in to trouble when using the Eval and the <%# %>, so it's probably some stupid thing (i hope)
For the first part, you definitely need to be using a binding expression:
<%# EditItemDiv.ClientID %>
The <%= %> scriptlet will have no context for each item. I assume you were "paraphrasing" the syntax you say you tried, so what didn't work before?
The "server tag is not well formed" is because you are trying to use double-quotes inside double-quotes. Change the outer to single-quotes:
Text='<%# Eval("Translation")%>'>
Basically, you can't nest similar quote types. Inline script will usually demand you use double-quotes, since single-quotes have a different meaning in c#, but you can use either double or single for markup parameter quoting. The upshot is that if you need to have inline script, use single quotes to wrap the markup parameter, which frees you to use double-quotes inside it.
If you need further single quotes in the output, e.g. to render a javascript parameter, just use '. You could also use " if you wanted to render double-quotes.
OnClientClick='openDiv('EditItem(<%# Eval("something") %>');'
As stated in my comment and by jamietre to fix the binding problem you need to change the code from:
Text="<%# Eval("Translation")%>"
to
Text='<%# Eval("Translation")%>'
As for the problem with the onclick of the span, it should work as you want if you just remove the runat="server" portion. I am not sure why, but it seems that adding this causes the controls to encode the onclick property.
If you need the runat="server" on the span then I will attempt to find another solution, but there are not guarantees.
I'm a bit new to .Net development, been working in Java for some time now. I have an aspx page and we need to externalize some strings to make it more flexible.
If I have a table somewhere and there is just a string sitting outside an asp tag, I can replace it so that
<th> Specific Foo String </th>
becomes
<th> <%= Strings.foo %> </th>
and everything is fine, the problem I'm running into is how do you do this kind of interpolation on an asp tag property
I tried changing
<asp:Label runat="server" ID="lblFoo" Text="Specific Foo String Entry" />
to
<asp:Label runat="server" ID="lblFoo" Text='<%= Strings.foo %> Entry' />
and
<asp:Label runat="server" ID="lblFoo" Text='<%#Eval("Strings.foo") %> Entry' />
but neither worked. Is what I'm doing not possible in the aspx file, I know that I can simulate this by rewriting their properties in the code behind, but that's a level of overhead I'd rather not deal with.
Thanks
I think you are looking to do this:
<asp:Label runat="server" id="label1" Text='<%# Strings.Foo + " Entry"%>' />
Then in your code behind (most likely in your OnPageLoad) you need to call
if(!Page.IsPostBack) Page.DataBind();
You need to be cautious however as calling DataBind on controls like textboxes or any labels that may have changed due to logic in the code behind will have their values overwritten with the bound values. Checking that you are not on a post back can help with this, but there are still gotchas.
Also note that I had to move the " Entry" text into the binding statement. If it is placed outside the last '%>' then the binding does not work and it will spit out:
<%# Strings.foo %> Entry
In the codebehind of the page you would do this:
lblFoo.Text = Strings.foo + " Entry";
A good place to put this code would be in the overriden OnLoad method but that is simply a suggestion as I am unfamiliar with your application and the life cycle needs of your page.
If you want to do all this in the aspx page then simply do this:
<span><%= Strings.foo %> Entry</span>
as a Label renders as a span anyhow.
If your objective is an HTML table of strings, then you can create either a ListView or a GridView and DataBind to that. It would save you the trouble of writing out all of your properties and will also produce the correct table tags for the data.
Without knowing more about your data, I cannot provide a detailed code snippet.
You're talking about resources. Read Basic Instincts Resources and Localization in ASP.NET 2.0 which shows you the built in resource editor, and how to use the "<%$ ... %>"-binding, or using meta:resourceKey attribute.
I can't seem to figure out why this does not work below. I need to bind the text box to a value from an inline expression. Seems like a simple thing right? But neither of these work. Any ideas? Thanks in advance.
<asp:textbox id="tbName" runat="server" Text='<%# Eval("test") %>' />
<asp:textbox id="tbName" runat="server" Text='<%= "test" %>' />
Edit:
I should mention that this page has no code behind and only the following directives at the top.
<%# Import Namespace="System" %>
<%# Import Namespace="System.Web" %>
<%# Page Language="C#" %>
Edit:
The only workable solution that I could come up with short of adding a code behind is adding an inline server script, like this one. I wish I knew why the inline expressions won't work unless you're in a data binding context.
<script language="C#" runat="server">
private void Page_Load(object sender, System.EventArgs e)
{
tbName.Text = "test";
}
</script>
In the Page_Load of you will have to make a call to Page.DataBind() for
<asp:textbox id="tbName" runat="server" Text='<%# Eval("test") %>' />
to work.
<%= %> is a shortened response.Write() and is never valid as an attribute, for any server tag.
<%# %> can be used, only if the conatainer is databound (the page in your case).
<%$ %> can be used to access data in resources files.
EDIT: You can also take a look at How to 'bind' Text property of a label in markup which is a smimilar question.
As stated, <%= %> is illegal anywhere within a server control declaration, except where inner markup is being parsed as content (eg <ItemTemplate> within a Repeater).
<%# %> is valid as an expression for control properties, as these expressions will be evaluated when DataBind() is called on the control.
Your use of Eval() looks a little suspect though. Per the example, Eval() will use the current Page object as the binding context, which means that the value of the public property named "test" will be bound to when DataBind() is called. Unless you actually have this property defined on the Page class, the expression will never evaluate to anything.
Eval() is mainly intended for use in expressions within controls such as Repeater, GridView, ListView, etc, where there is a list of data items being bound using templates, and you need a method to be able to access the properties of the current data item.
For all other controls, just use normal code expressions inside a data-binding expression - it's much faster, and more intuitive than Eval(), which relies on runtime reflection.
If you want a more clever alternative using <%$ %> syntax that avoids data-binding altogether, go here:
http://weblogs.asp.net/infinitiesloop/archive/2006/08/09/The-CodeExpressionBuilder.aspx
Use <asp:textbox id="tbName" runat="server" Text='<%# Eval("test") %>' />
and set tbName.DataBind(); in page load event.
For those who are searching for more info about inline expressions, refer to the following links.
ASP.net have the following inline expressions
Embedded code blocks <% ... %>
Displaying expression <%= ... %>
Directive expression <%# ... %>
Data-binding expression <%# ... %>
Expression builder <%$ ... %>
Server-side comments block <%-- ... --%>
You might need the namespace for the textbox control
<%# Import "System.Web.UI.WebControls" %>
Try adding runat="server" to the server elements.
Otherwise, this element will not be processed at server.
EDIT: Actually, "its correct" that this doesn't work; code <%=...%> cannot be evaluated in a server tag, only expressions like for instance <%$ Resources: h1 %>
<asp:textbox id="tbName" runat="server"><%="test"%></asp:textbox>