how to get server.MapPath in asp.net core from inside a helper

Question

having a helper method like this:

 public static IHtmlContent Source(this IHtmlHelper html, string s)
 {
     var path = ServerMapPath() + "Views\\" + s;

I need to get the equivalent of Server.MapPath in asp.net core

Answer 1

You need to inject IHostingEnvironment. Then:

var path = env.ContentRootPath + "Views\\" + s;

in an html helper you can do this:

((IHostingEnvironment)html.ViewContext.HttpContext.RequestServices.GetService(typeof(IHostingEnvironment))).ContentRootPath;

Answer 2

recommended Solution

I recommend Don't use a static class. You can keep something similar to your class, and register it as a singleton.

public class SourceClass
{
    private readonly IWebHostEnvironment _webHostEnvironment;

    public SourceClass (IWebHostEnvironment webHostEnvironment)
    {
         _webHostEnvironment= webHostEnvironment;
    }

    private IHtmlContent Source(this IHtmlHelper html, string s)
    {
        string contentRootPath = _webHostEnvironment.ContentRootPath;
        Path.Combine(contentRootPath,"Views",s)
    }
}

Then, in Startup.ConfigureServices:

services.AddSingleton<SourceClass>();

Finally, inject SourceClass where you need it, instead of just statically referencing the class.

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Another Solution

(Note :@regnauld provided this solution, but it had some drawbacks, which I thought would be fully answered)

But if you want to use a static method you can do(Note: In .Net Core 3 IHostingEnvironment is absolute and IWebHostEnvironment must be used instead ):

• for ServerPath ,use

  ((IWebHostEnvironment)html.ViewContext.HttpContext.RequestServices.GetService(typeof(IWebHostEnvironment))).ContentRootPath
  

OR

• for WebRootPath (wwwroot) ,use

  ((IWebHostEnvironment)html.ViewContext.HttpContext.RequestServices.GetService(typeof(IWebHostEnvironment))).WebRootPath
  

in this answer you can find more details.

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I also recommend that you use this code:

var path = Path.Combine(WebRootPath,"Views",s)

instead of

var path = WebRootPath + "Views\\" + s

to run the code on all operating systems.