C# and ASP.NET MVC: Using #if directive in a view

Question

I've got a conditional compilation symbol I'm using called "RELEASE", that I indicated in my project's properties in Visual Studio. I want some particular CSS to be applied to elements when the RELEASE symbol is defined, and I was trying to do that from the view, but it doesn't seem to be working.

My view code looks like this (shortened a bit for demo purposes):

<% #if (RELEASE) %>
    <div class="releaseBanner">Banner text here</div>
<% #else %>
    <div class="debugBanner">Banner text here</div>
<% #endif %>

With this code, and with the RELEASE symbol set, the 'else' code is running and I'm getting a div with the debugBanner class. So it doesn't seem to think that RELEASE is defined. It's worth noting that my actual C# code in .cs files is recognizing RELEASE and runs the correct code. It's only the view that is giving me the problem.

Does anyone have any insight into this? Any help would be appreciated. Thanks.

Clarification: I should have mentioned that this view is already a partial view, and I'll simply render it in pages where I need it. That's because these banners will be on certain pages and not others. So even when rendering it as a partial view via:

Html.RenderPartial("BannerView");

it's not working.

Jenifferjenilee

Why don't you create a html helper method and put your code in there? You can then do the if and do a render partial to keep the HTML – Select

Not too familiar with html helper methods. I did clarify my question to indicate that this is a partial view I'm working with. Can you elaborate a bit on your suggestion? – Jenifferjenilee

preprocessor directives only work @ compile-time... @DeveloperArt has an elegant solution... – Delightful

Adding the keyword "constant" to this page so it gets returned for searches for "compiler constants". (hopefully) – Birdie

See: https://mcmap.net/q/112070/-using-conditional-compilation-symbols-in-mvc-views for another alternative to using conditional compilation in views. – Boogiewoogie

Answer 1

In your model:

bool isRelease = false;

<% #if (RELEASE) %>
    isRelease = true;
<% #endif %>

In your view:

<% if (Model.isRelease) { %>
    <div class="releaseBanner">Banner text here</div>
<% } else { %>
    <div class="debugBanner">Banner text here</div>
<% } %>

Lactobacillus

I'm gathering from this answer that it's not possible to check compilation symbols from a view, and that is must be done from a .cs file. Is this true? – Jenifferjenilee

Nice solution, but what about placing this logic in a base controller that all Controllers inherit. Then you could have access of this property through all Controllers... – Delightful

well, not sure that would completely work xander. To have access to it from the view, we would need a Model with that property, not a Controller with that property. So I'd really have to pass that same Model from multiple controllers and render that view, which would be sort of a pain. – Jenifferjenilee

If you place that logic in a base controller and access it from a derived controller then you could assign it to ViewData or some custom ViewModel – Delightful

So actually, what I'm going to do is set a property in one of our Global files, which should solve the problem. Same general principle as Develop Art's solution, but slightly tweaked. Thanks for the responses. – Jenifferjenilee

I think creating an HtmlHelper extension will be better, but good to know that views are always in Debug – Denominator

Answer 2

I recently discovered that you can simply test:

HttpContext.Current.IsDebuggingEnabled

in Views, which saves you checking symbols in other parts of your app.

Rabush

This is the best approach, IMO. – Carduaceous

Shouldn't you use this.Context.IsDebuggingEnabled instead? Really only applicable if you've mocked the context or somehow used razor views outside of a webapp – Moorer

I've tested this in development environment, and by publishing locally (my machine, to a folder, .pubxml) using IIS , and it works just fine. Year 2022, using VS22, in NET Framework 4.8 project. – Aplomb

Answer 3

A better, more generic solution is to use an extension method, so all views have access to it:

public static bool IsReleaseBuild(this HtmlHelper helper)
{
#if DEBUG
    return false;
#else
    return true;
#endif
}

You can then use it like follows in any view (razor syntax):

@if(Html.IsReleaseBuild())
...

Spreader

of course, the caveat is that it depends on where this method is -- if it's in a shared library that has been compiled in release mode, it'll return false when included in a project compiled in debug mode. – Moorer

Please check this question #28400635 – Clout

Where this method should be placed? In a controller? A separate class? – Libriform

Answer 4

@if (HttpContext.Current.IsDebuggingEnabled)
{
    // Debug mode enabled. Your code here. Texts enclosed with <text> tag
}

Winifredwinikka

Answer 5

You can use ViewBag instead of viewmodel (but viewmodel-like approach is better) :

Controller :

View :

@{
   bool hideYoutubeVideos = ViewBag.hideYoutubeVideos ?? false;     
}

Usage :

@if (!hideYoutubeVideos)
{
     <span>hello youtube</span>
}

Also, be sure, that NIKITA_DEBUG variable exist in build tab of your project :

Deportment

Answer 6

For me, the code below has worked very well. When the application is Debugging my buttons appear, when is Release, don't.

@if (this.Context.IsDebuggingEnabled)
{
    <button type="button" class="btn btn-warning">Fill file</button>
    <button type="button" class="btn btn-info">Export file</button>
} 

Arin

Answer 7

You can use Debugger.IsAttached like this:

@using System.Diagnostics

@{
    string gridID = $"the-grid-7";

    if (Debugger.IsAttached)
        gridID = gridID + new Random().Next(1, 1000).ToString();

    var loadUrl = ViewBag.LoadUrl;
}

Schroeder

Answer 8

Below is the Razor syntax for conditional compiler directives. It loads the developer version of jquery when DEBUG variable is set in VS profile or web.config. Otherwise the min version is loaded.

    @{
#if (DEBUG)
    }
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.6/jquery.js"></script>
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.12/jquery-ui.js"></script>
    @{    
#else
    }
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.6/jquery.min.js"></script>
       <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.12/jquery-ui.min.js"></script>
    @{
#endif
    }

Sidon

don't think this will work since the views aren't compiled and if(DEBUG) is a compiler directive? – Badillo

That does not work in Razor. That is exactly what the original question about. – Pauwles

I edited the post to match the current razor sytnax, which this answer was for. This is not "classic ASP" syntax, but it is the "ASP.NET Web Pages (Razor) 3", which is the current one I believe. – Alligator

You will need to recompile the views and it does not seem to consistently work either, so better go with the Helper approach. – Alligator