Reusing ASP.NET code in multiple pages

Question

Is there a way to reuse a piece of ASP.NET code (that tag-based code, not the code-behind) in many different pages? For example I have a <div> with some contents in it that appears in 5 different pages of my site. I'm looking for a technique through which I could save this <div> in a separate web-content file so to speak, with maybe a different extension like MyDiv.ASPC and could then do a server-side tag anywhere in a webpage like:

<asp:Import href="~/MyDiv.aspc" />

and ASP.NET would inject the entire content of this file at that point where this tag appears.

I thought of creating a user control for this, but I'm not sure if a user control always injects precisely what is written in its body, or could there sometimes be unwanted tags generated by user control itself.

Or are there existing better ways of doing this?

Edit

About Master Pages, they are far away from what I'm looking for. They are actually good for a common basic layout of your website. My idea is quite opposite of that. My pages do not have a common layout; it is just that they have one common <div>. It is more closely fulfilled by a UserControl.

For UCs, my fear is that they generate more than what is written in their body, whereas what I'm after is a simple text injection. To put it technically, what I'm looking for is basically a preprocessor step (kind of #include thing in C++) rather than a compiler step, if you see what I mean.

Answer 1

You need to use ASP.NET User Controls, as these are specifically created to be the solution to the problem you are describing. For more information, see MS Documentation.

From their documentation...

In addition to using Web server controls in your ASP.NET Web pages, you can create your own custom, reusable controls using the same techniques you use for creating ASP.NET Web pages. These controls are called user controls.

A user control is a kind of composite control that works much like an ASP.NET Web page—you can add existing Web server controls and markup to a user control, and define properties and methods for the control. You can then embed them in ASP.NET Web pages, where they act as a unit.

Answer 2

An empty userControl would do just that - nothing. A user Control just adds it's contents to the page, or usercontrol hosting it. It adds nothing extra.

UserControls give you a nice easy page fragment type approach to reusing content. They work great within a project & most people use them for just that.

If you wanted to make something more reusable across projects, you could write server control. It's more involved, but much more reusable. Google should be able to find you many tutorials on how to do this.

Answer 3

Ran a short test. User Controls do not enter extra tags as long as you don't place any Runat="Server" tags in it, so this would indeed be a solution I guess.

You can also read output from a cache object where you would read your files.

So

<%= Static.ContentXyz %>

would mean:

public static class Static
{
    public static string ContentXyz
    {
        get
        {
            string s;

            if (!this.cacheDictionary.TryGetValue("ContentXyz", out s))
            {
                s = File.ReadAllText(Server.MapPath("ContentXyz.html"));
                this.cacheDictionary("ContentXyz", s);
            }

            return s;
        }
    }
}