Simple HTML construction in ASP.NET ?

Question

A simple question, I think:

I want to put a tag into an ASP.NET app I've been asked to maintain, so I'm coming at this from a newbie point of view just tinkering around the edges without knowing a lot.

I wrote an old ASP application back in 1998, so I am just running on memory...

How do I write some output to the webpage?

I know I can use an

<asp:label id="blah">

but then I need to define a Label blah; in my code behind and then assign it.

I believe that I can put in-place:

<% Response.Write("sometext"); %>

and that will write sometext in the location within the page. (Am I correct?)

Lastly, I remember there was a syntax to the effect of

<%= "some string" %>

but I can't find the documentation on it, to say either it is deprecated, unadvised, or the rationale for such a decision.

I have tried googling for "ASP.NET grammar" but I can't even find a good description that "<%=" even exists, though it is mentioned in a few blogs.

For something simple, like inject the global version number, or the current date, then I can't see anything particularly wrong with in-place composition - it would save me defining 15 labels and having to initialise them all - though perhaps the asp:label approach could reference one global instance of a label?

Just asking for opinions on good practices :)

Answer 1

<%= string %> is perfectly valid ASP.NET syntax. The reason you will often find references to problems with using that is people use <%= (equivalent to Response.Write) when they should use <%# (for databinding) or vice-versa.

For example, we use it very extensively in our content managed site, where we pull in values from a global settings repository:

<%= SiteContext.Current.GetSetting("SiteTitle") %>

MSDN:

• MSDN entry on <%= (this is under the JScript.NET section but still applies)
• MSDN entry on <%#

Some others suggest <%= is not a "best practice" or a very good approach, but I strongly disagree with that sentiment. For an MVC-ish type site (especially a site that is template- or view-driven in some way), the most direct approach is frequently more effective than using server controls.

Answer 2

Look up the term "render blocks" for the <% %> syntax.

How about using

<asp:Literal id="z" text="goofy" runat="server" />?

Labels are usually used with forms.

Answer 3

There are lots of options. You could use a single label, and string concatenate all the data you want displayed in that location.

You could create a user control with the layout you want and assign values that way.

You could inject it directly with response.write or the <%= %> syntax

You could create an HtmlGenericControl in your code behind (it's a div), add some text to it, and inject it into the pages controls collection.

Whatever you pick, try and go with the existing style of the coded page.

Answer 4

Go with the <asp:label /> (or a literal control if you want to customize some html in the content). Seriously. I'ts not that hard: when you put label in your markup visual studio will create it in the code-behind for you, so there's no extra work involved.

You could use the <%= "some string" %> syntax in web forms, but there can be issues when mixing that with the asp controls and there's a good reason new frameworks moved away from mixing logic like that in with your markup.

Answer 5

Just be mindful that when you use an <asp:Label /> it renders the .Text inside the <span> tag whereas an <asp:Literal /> adds no extraneous HTML to the string passed to it.
For example, if you were building a content management system and wanted to display user-driven HTML, a Label control would not correctly display the output from a WYSIWYG type rich textbox whereas a Literal control is the appropriate choice.

The <%= %> is the late-bound equivalent of the Literal's .Text property. The only difference here is when the value is placed in the page (aside from obvious syntax and separation of concerns paradigm) during the course of the page lifecycle.

Since the .Text property is on a control inherited from WebControl, it can be set/read/manipulated during any of the events following the control's Load event (wherever/whenever you load the control inside the page), but the <%= %> text cannot be directly read/used/manipulated by the code-behind without referencing some other control to get to it (like a containing div's InnerHtml property).

Answer 6

You can also take full control of the rendering of your pages and controls and compose whatever you need to. You control the HTML, the order of rendering your controls, etc...