在ASP.NET MVC中，View中的IF..ELSE语句是否被否决？

Question

I know that you want to keep logic out of your views. I can elimate most loops by using DisplayFor/EditorFor and passing IEnumerables to the view.

What about IF statements? should they be avoided completely in views? used sparingly? as a last resort?

Say you wanted to show hide an element based on a User role...How would u go about doing this without an IF statement...a completely seperate view perhaps?

Just trying to get an idea of best practices.

Thanks!

Answer 1

Be consistent, and keep in mind the purpose of the view - to produce your HTML. Toward that end, certainly you will need some if constructs here or there. I think some people are suggesting you stick to some pie-in-the-sky, ultra-nitpicky purism here at the expense of usable, functional, well-defined code.

Answer 2

只要您不最终将后端逻辑放入视图中，就可以在视图中使用if 。

Answer 3

Rob Conery has a rule of thumb that states "if there's and IF, make a helper" . Personally, I would say "use sparingly". I avoid it as much as possible because it makes things more difficult to unit test.

For the situation where you want to hide elements based on user roles: For simple scenarios, I would probably put the check directly in the view. Usually I try to still make these more terse and testable, though. So instead of:

@if (HttpContext.Current.User.IsInRole("admin")
{
    // Show admin stuff
}

I would do something like:

@if (Model.UserIsAdmin)
{
    // Show admin stuff
}

On the other hand, if these kinds of checks started getting speckled all over your views, I'd probably create the elements conditionally in the viewmodel first, and then just display what's been built. Hope that helps.

Answer 4

Basically every View should display whats passed in ViewModel. If ViewModel is not enough, then I would look for a way of improving the ViewModel creation itself, not the View's logic.

All conditionals CAN be evaluated upon ViewModel creation.

Of course, It all depends on how much custom-logic in View does Your project organization tolerates.

Answer 5

If / else can be used sparingly, in my opinion, but for the example you mention, hide an element based on role - the if check should definitely not be in the view. Write extensions and helpers where needed.

Answer 6

我认为最好避免在视图中使用，在示例中应避免在视图中使用business（Model）或application（Controller）逻辑，可以创建不同的Partial View以显示某些依赖于用户角色的视图，并在Controller中放置您需要显示的视图的逻辑

Answer 7

我建议在视图中通过“ if”隐藏元素，但是在代码中必须禁用由隐藏元素激活的功能（方法）。