How powerful is the <script> tag in ASP.NET?_问答_开发者

I'm new at web development with .NET, an开发者_C百科d I'm currently studying a page where I have both separated codebehinds (in my case, a .CS file associated to the ASPX file), and codebehind that is inside the ASPX file inside tags like this:

<script runat="server">
//code
</script>

Q1:What is the main difference (besides logical matters like organization, readability and ETC), what could be done in one way that could not be done in another? What is each mode best suited for ?

Q2:If I'm going to develop a simple page with database connection, library imports, access to controls (ascx) and image access in other folders.. which method should I choose ?

Anything you can do in a code-behind, you can do in an inline script like what you posted. But you should use a code-behind most of the time anyway. Some things (like using directives) are just a little easier there, and it helps keep your code organized.

Q1: Nothing. Aside from what you and the others have mentioned (separation, readability), you can do everything "code behind" can do with "inline" (code within page itself) coding.

Inline coding doesn't necessarily mean its like "spaghetti code" where UI and code are mixed in (like old-school ASP). All your code can live outside of UI/HTML but still be inline. You can copy/paste all the code-behind code into your inline page and make a few adjustments (wiring, namespaces, import declarations, etc.) and that's that.

The other comments hit the nail: portability and quick fixes/modifications. Depending on your use case, you may not want certain sections of code exposed (proprietary), but available for use. This is common for web dev professionals. Inline code allows your customers to quickly/easily customize functionality any way they want to, and can use some of your (proprietary) libraries (dlls) whenever they want to, without having to be code jocks (if they were, they wouldn't have hired you in the first place).

So in practical terms, it's like sending off an "html" file to clients containing instructions on how to change things around (without breaking things)...instead of sending off source code files along with html (aspx) pages and hoping your clients know what to do with them....

Q2: While either style (inline or code-behind) will work, its really a matter of looking at your application in "tiers". Usually, it will be: UI, business logic and data tiers. Thinking about things this way will save you a lot of time.

Practical examples:

If more than one page of your web app must expose/access data, then having a data tier is the best approach. Actually, even if you currently have a 1 page need, its likely never going to stay that way, so think of it as best practice.
If more than one page of your web app will collect input from users (i.e. contact us, registration/sign up, etc.) then you're likely going to need to validate input. So instead of doing this on a page by page basis, a common input validation library will save you time, and lessen the amount of code you need.

In the above examples, you've "separated" a lot of the processing into their own tiers. Your individual html/aspx pages can then use the "code libraries" (data and input validation) quickly with minimal code at the "page level". Then the decision to use either inline or code-behind styles at the "page level" wouldn't matter much - you've essentially "dumbed it down" to whatever your use case is at the time.

Hope this helps....

Keep it separated. Use the .aspx page for your layout, use the .aspx.cs page for any page specific code and for preference, pull your data access/business logic out into their own layer, makes for much simpler maintenance/re-use later on.

Slight caveat there - ASP.net MVC uses inline scripts in it's views, and I've really come round to that idea - it can keep the simple stuff simple, but the architecture used in MVC ensures that your business code remains separate from your presentation code.

I'm not saying you should ever be hacking live code... but one bit of flexibility from having the "code behind" as in-line script is that you could hack in changes without having to rebuild/publish the site.

Personally, I don't ever do this but I've heard instances where people have done it to get in an emergency fix.

There is no difference between the script tag and code behind. The code behind option actually came out of using the script tag or the <% %> from "Classic ASP". A lot of developers didn't like the fact that they server side code sat along side the UI code, because it made the file look messy, and it was a lot more difficult for the HTML people (web designers or whatever you would like to call them) to develop on the same page as the developers at the same time.

Most people like using the code behind option (It's actually considered the standard way of doing things), because it keeps the UI and the Code separate. It's what I prefer, but you really can use either.

You can use all the same stuff
Always try to keep the code separated unless you have a compelling reason not to

Funnily enough, I used the <script runat="server"> in the code infront only today! I did this because you do not need to Build the whole web application to deploy a fix that needs code behind. Yes- it was a bug fix ;)