I have a literal in my aspx called xxx.
Now lets go into the JS world.
I always used :
alert('audit.aspx?claim_id=<%= xxx.Text%>');
But Ive seen a code like this :
alert('audit.aspx?claim_id=<asp:Literal id="xxx" runat="server" />');
This is also working.
Can I conclude that the <asp:Literal is equal to <%= syntax ?
I know that he is a RUNAT server Item...
but again - I want to see the differences.
The asp:Literal control simply outputs the value of its Text property when the page is rendered. That's why the resulting JavaScript looks the same when viewed by the client. But the two are not the same, no.
<%= xxx.Text %> explicitly reads the value of this text property and writes it out. The Literal control will be elsewhere on the page, where its Text property will also be written out.
Placing the asp:Literal control within your JavaScript relies on the rendering of this control to place the value there, and because this is its location within your page, there's no need to have the same content rendered elsewhere.
However, neither taken in isolation seems an appropriate use of this control to my mind. If you have simple text you want written out, then expose it as a property of your Page-derived code-behind class.
The Literal class is basically a placeholder for text, but it also exposes events which you can hook into for greater control.
Have a look at the API here http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.literal.aspx
Related
I'm making a user control to gather all the functionality for popups on my website in one place. When someone instantiates the control, they'll pass in a PopupID attribute, which is assigned to the id of a div inside the control, and will be used to call show() and hide() functions in javascript. I'm going to use content templates so that different stuff can be put inside the control by different kinds of popups.
The html for the popup will look something like this:
<div id="<%=PopupID %>" class="popup box" runat="server">
<asp:PlaceHolder runat="server" ID="popupPlaceHolder"></asp:PlaceHolder>
</div>
However, there is a problem: asp.net has the habit of giving controls different IDs when served up to the client than what you write in the html. So the ID of that div might not be <%=PopupID%> It could be somethling like #ctl00_whatever_<%=PopupID%>. Usually I get around this by putting something like:
<script type="text/javascript">
var ddlCountry0 = '<%=ddlCountry0.ClientID%>';
var ddlActivity0 = '<%=ddlActivity0.ClientID%>';
var chkPrivateContacts = '<%=chkPrivateContacts.ClientID%>';;
</script>
In the header for the page. Then when refering to things in the javascript you just do $(ddlCountry0) instead of $('ddlCountry0'). However, I don't see how I can do that in this case, As I don't know the ID of the element until someone instantiates it. What do I do to get around this?
Does the user control have CreateChildControls and OnPreRender methods you can override?
If a control is added and ID set correctly during CreateChildControls...the ClientID property is populated during OnPreRender, at which point the control itself could inject the necessary script block into the body or page header. People often use jQuery to help with this situation:
headerScript.AddLine("var ddlCountry0 = $('[ID$=" & Control.ClientID & "]').attr('id');")
Is that along the right lines?
In the end, I used ClientIDMode=Static to get around these problems.
Page_Load generates a string of HTML for a dashboard. (html)
What control on an aspx page to bind that "text" to so when the page renders you see the tables, and buttons within?
Tried
With dhtml.Text = html but I don't see the buttons. I do see the tables as well as the borders of cells that I expect.
Any ideas?
TIA
You can inject any text/html into your ASPX page using: <% =GetMyText() %> where "GetMyText()" is a public or protected method in your code behind that returns a string.
You can also drop a Literal control onto a form and set the text via its "Text" property.
But if you want to do things the ASP.NET way, you might use a Gridview or Repeater to display tabular/repeating data, and Databind to it with some data.
If you are starting out with ASP.NET, you would probably be better off learning ASP.NET MVC as it is easier to get your head around if you are used to writing HTML. ASP.NET Web Forms, which you are using, generally tries to insulate you from HTML, CSS, and Javascript by giving you controls that you drop onto the page and bind data to. The controls do a lot of work for you, but take away almost all control of your HTML, CSS and Javascript.
I use javascript to dynamically create html elements. Your page_load function could register a javascript function which creates the elements you need.
Not sure why you were downvoted, but a very simple one to use is the HtmlGenericControl.
Basically, just add a span or div to your .aspx file and give it an ID and the runat="server" attribute.
Then, in your code behind just set the InnerHtml property of that control to your generated html.
Ok, so here is the setup. I have a master page. The page is assigned to a aspx file programatically in the PreInit function. This all works as expected.
I have a function that runs through all the controls on the page an looks for ContentPlaceHolder controls with specific IDs. When a specific ID is found the control is processed (specific content is placed there based on the ID and other information). This all works as expected.
I have a situation where I would like to pass information to my processor function from the control. I would like to be able to, based on an attribute, do different things. For example I would like to be able to put something like this on the masterpage:
<asp:ContentPlaceHolder id="CMS_EXTRABLOCK1" type="text" runat="server"></asp:ContentPlaceHolder>
Note that the type="text" attribute is not a standard attribute. I would like to be able to in the c# code do something like where ctrl is the ContentPlaceHolder.
if (ctrl.Attributes["type"] == "text") {} else {}
Now none of that will work as I get a parse error with the added attribute. So is there a way around the problem while still using the ContentPlaceHolder control? If at all possible I would like to continue using the ContentPlaceHolder control type for consistency with the rest of the code. If I can't use the ContentPlaceHolder in any manner then what would be an equally ideal asp control for this type of situation?
Its simple if I have an ASP.net page with an ASP.net linkbutton / hyperlink
and I obtain a value from say a SQL Database and I store it in the label...
For example:
this.myLabel.Text = someValueReturnedFromADatabase
This is simple because it goes right to the code behind page and set the text value
to the value returned from my database (aside from going into more details with data access layer, etc).
What I was wondering is what if I dont want to use an ASP.net linkbutton and I simply want to use an HTML link button (as I need to call the jquery fade function). How would I set the value someValueReturnedFromADatabase to a control that is not runat=server?
Have a variable in your codebehind:
protected string TextForLabel
Set it in Page_Load, or wherever:
TextForLabel = someValueReturnedFromADatabase;
Reference it with pointy-bracket percent notation:
<% =TextForLabel %>
You can set runat="server" on standard html controls. I do it all the time. Then you will be able to access their properties in your code behind just like you do for asp controls.
If I am not mistaken, for labels you can use .InnerText or .InnerHTML to change the text.
From what I know of, you need to make some sort of relation between your HTML document and the code behind to interact with data from a SQL database. Either that or you'll have to make the entire database connection etc. in the HTML header using script type="text/javascript" and script type="text/C#" or whatever language you use to develop.
I've noticed that on most, if not all, standard web controls in the System.Web.UI.WebControls namespace, you can add any properties you want to them without crashing the page.
Take the asp:Button control for an example.
This code is perfectly valid:
<form runat="server">
<asp:Button runat="server" Text="Test button" crapAttribute="crapValue" />
</form>
Now, I've got a custom server control which crashes if I add arbitrary attributes to it. It only accepts attributes which have a corresponding public property defined.
The error I get is something like this "The control does not have a public property named "crapAttribute" ".
I would like my custom controls to accept any attribute without crashing. What do I need to do for that to work?
I've looked at the standard controls in Reflector and they do have all kinds of attributes and stuff but there was nothing that I saw which immediately caught my eye.
My custom controls are inheriting from WebControl for what it's worth.
You don't have to do anything in particular to allow arbitary attributes to be added the control markup. Things deriving from WebControl would normally scoop up these attributes and dump them in the Attributes collection.
I can't think of reason why this would fail. You would have to remember to render the Attributes collection in your implementation of Render if you have one.
Can you add a simple example of the code of a new control that fails to your question?
One way of doing it is adding the custom property in code behind
myCustomControl.Attributes.Add("customproperty", "value");
This should do the job for you.
However, I am interested in knowing how to do it in the server control itself.