How do I code a MVC3 Helper - database

Question

I’ve just build my first Helper in MVC, it’s very basic and just displays a string where ever I use it. So it’s a .cshtml file in my App_Code folder, I think that is how it's supposed to be set up, with the following code in it,
#helper DisplaySelect() {
#:This text is coming from an helper class.
}
Now I am a wiz with helpers how do I make it do things. E.g.. say I want it to query the database and display something, I would normally do that work in my controller. How do I do that with helpers, do I create a helper controller and then treat the helper like a partial view???
Any help would be greatly appreciated.
Cheers,
Mike.
Thanks guys,
I’ve asked that question before Shark “Why would you use a helper and not a partial view” the answer I got there was a partial view is more for just displaying common HTML where as a Helper can have a bunch of code in it and do all kinds of great processing stuff. Now it seems that’s not true and they are pretty much the same thing, in some respect, except in Link664’s case!
I like what you’re saying Link664 that makes sense as it cleans up the code nicely.
What I was going to do was try and populate a drop down list in a helper and then use it in multiple places, but from my research today that’s not what helpers are for.
Cheers,
Mike.

Answer 1

I'm a bit confused by what you want to do and why you want to do it but I'll give it a go. As you mentioned, you would normally do that work in your controller. It is very poor design to make database calls from a partial view/html helper created client-side.
The #helper syntax is to be used only for simplifying view code, not for implementing code that should be in the controllers or models in the view. See this article for a better idea of when you should be using them.
As for your example, I recommend you pass the data that you want from your controller and create an extension method on HtmlHelper to render it in your view. For example if you wanted to display a list of the most recent 10 posts on your view:
public static HtmlString RecentPostsDisplay(this HtmlHelper html, string name,
List<Post> values, object htmlAttributes)
{
var tag = new TagBuilder("ul");
...
//build list content by looping through values and adding to TagBuilder
...
return new HtmlString(tag.ToString(TagRenderMode.SelfClosing));
}
and in your controller
public ActionResult Blah()
{
ViewBag.posts = _db.GetMostRecentPosts();
return View();
}
Then in your view you can put
#Html.RecentPostsDisplay(ViewBag.RecentPosts)
Hopefully that is what you are looking for, if not update your question so it's not so ambiguous and I'll try again!