ASP.NET MVC - Find Absolute Path to the App_Data folder from Controller

Question

What is the correct way to find the absolute path to the App_Data folder from a Controller in an ASP.NET MVC project? I'd like to be able to temporarily work with an .xml file and I don't want to hardcode the path.

This does not work:

[HandleError]
public class HomeController : Controller
{
    public ActionResult Index()
    {
        string path = VirtualPathUtility.ToAbsolute("~/App_Data/somedata.xml");

        //.... do whatever 

        return View();
    }

}

I think outside of the web context VirtualPathUtility.ToAbsolute() doesn't work. string path comes back as "C:\App_Data\somedata.xml"

Where should I determine the path of the .xml file in an MVC app? global.asax and stick it an application-level variable?

I guess in a Seperation of Concerns & Testability sense - VirtualPathUtility.ToAbsolute() shouldn't work. But then what is the right way to do this? — BuddyJoe, Aug 12 '09 at 21:09

score 417 · Accepted Answer · edited Dec 10 '16 at 02:39

417

ASP.NET MVC1 -> MVC3

string path = HttpContext.Current.Server.MapPath("~/App_Data/somedata.xml");

ASP.NET MVC4

string path = Server.MapPath("~/App_Data/somedata.xml");

MSDN Reference:

HttpServerUtility.MapPath Method

edited Dec 10 '16 at 02:39

Loudenvier

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answered Aug 12 '09 at 21:12

eu-ge-ne

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@Cleiton Except that Url.Content gives a URL, not a server path. – Andrew Dunkman Apr 16 '12 at 14:43
8

for mvc4 it is only Server.MapPath() – SeriousM Nov 14 '12 at 13:19
I used this in MVC3 and only needed `HttpContext.Server.MapPath` Adding `Current` gave an error. – Paul Jan 18 '13 at 21:10
6

The MVC4 way didn't work, I either had to use `Current` or `Server.MapPath(...)` as SeriousM mentioned. – gligoran Jan 22 '13 at 21:44
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Use `System.Web.Hosting.HostingEnvironment.MapPath()` – Razor Apr 23 '13 at 23:56
What is the difference between this methods? Is it just name spaces? – Johnny_D Sep 12 '13 at 13:13
1

Calls to HttpContext.Current don't work in some situations where there isn't an HttpContext (application_start etc) – mcintyre321 Sep 15 '14 at 12:18
For those who have App_Data located in class library project and running the code locally doesn't work, can try `Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().CodeBase), "App_Data/somedata.xml")` – SpringMaple Aug 29 '22 at 05:45

Alex from Jitbit · Answer 2 · 2019-06-07T10:18:28.910

280

string path = AppDomain.CurrentDomain.GetData("DataDirectory").ToString();

This is probably a more "correct" way of getting it.

edited Jun 07 '19 at 10:18

answered Nov 22 '10 at 09:13

Alex from Jitbit

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May I ask why? A short explanation would be nice. – winsmith May 26 '11 at 09:44
25

Because it's not hardcoding the "App_Data" string. That can change in the future versions, or be different in Mono etc. etc. – Alex from Jitbit May 27 '11 at 05:32
20

The nice thing about this answer is that I can use it in my Model project _without_ referencing system.web, thus helping to keep a clean separation. Nice one! – flytzen Nov 06 '11 at 10:11
1

Great answer thank you - this is perfect for finding App_Data directory from within a WCF Workflow Service. – David Clarke Nov 30 '11 at 02:13
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This blog post explains this solution http://vaultofthoughts.net/GettingTheLocationOfAppDataFolder.aspx – Pete Davis Jan 09 '12 at 03:09
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The blog post Pete refers to also talks about why using this might not be a great idea. – Andy Apr 06 '12 at 16:45
13

Not documented in [MSDN](http://msdn.microsoft.com/en-us/library/system.appdomain.getdata.aspx), therefore should not be used. – Alexander Abramov Apr 10 '12 at 10:14
The benefit of MapPath, is that you can mix-in your full path, otherwise you would be forced to use Path.Combine to build up the path using this answer here. – Kind Contributor Mar 25 '14 at 05:06
2

the nice thing about hardcoding 'App_Data' (and I admit I hate some of these strins) is that anybody looking at this code in future will be able to instantly see what it is you're doing - whereas "DataDirectory" quite likely might confuse people – Simon_Weaver Feb 09 '15 at 20:21
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Hard-coding another string instead of "App_Data" is not a "correct" way. Besides, there are no more app domains in .NET Core. – UserControl Sep 23 '15 at 19:56
I think this is the correct way to do it. It works when I run "update-database" in the package manager console to seed my database using data in a CSV file in the app_data folder. At that point, there is no HttpContext. Thank you so much! – user275801 Nov 14 '16 at 08:45

Simon_Weaver · Answer 3 · 2016-07-06T05:29:53.920

146

I try to get in the habit of using HostingEnvironment instead of Server as it works within the context of WCF services too.

 HostingEnvironment.MapPath(@"~/App_Data/PriceModels.xml");

edited Jul 06 '16 at 05:29

answered Apr 10 '10 at 10:27

Simon_Weaver

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Server.MapPath() ultimately calls HostingEnvironment.MapPath(), see http://stackoverflow.com/questions/944219/what-is-the-difference-between-server-mappath-and-hostingenvironment-mappath – Kind Contributor Mar 25 '14 at 05:09
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This is my favorite since I can use it outside of my controllers. This is in the `System.Web.Hosting` namespace in case anyone needs to know the relevant `using`. Ref: https://learn.microsoft.com/en-us/dotnet/api/system.web.hosting.hostingenvironment – MDMower Feb 18 '19 at 19:27

score 9 · Answer 4 · answered Oct 23 '12 at 11:05

9

The most correct way is to use HttpContext.Current.Server.MapPath("~/App_Data");. This means you can only retrieve the path from a method where the HttpContext is available. It makes sense: the App_Data directory is a web project folder structure [1].

If you need the path to ~/App_Data from a class where you don't have access to the HttpContext you can always inject a provider interface using your IoC container:

public interface IAppDataPathProvider
{
    string GetAppDataPath();
}

Implement it using your HttpApplication:

public class AppDataPathProvider : IAppDataPathProvider
{
    public string GetAppDataPath()
    {
        return MyHttpApplication.GetAppDataPath();
    }
}

Where MyHttpApplication.GetAppDataPath looks like:

public class MyHttpApplication : HttpApplication
{
    // of course you can fetch&store the value at Application_Start
    public static string GetAppDataPath()
    {
        return HttpContext.Current.Server.MapPath("~/App_Data");
    }
}

[1] http://msdn.microsoft.com/en-us/library/ex526337%28v=vs.100%29.aspx

answered Oct 23 '12 at 11:05

Daniel Lidström

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How could static `HttpContext.Current` ever _not_ be available in one place if you are using it - via an IoC container - in another place? Where would the static property not be available? – M. Mimpen Mar 10 '15 at 10:44
It will only be available in web project. Does this answer your question? I'm not sure I understand fully. Today I think I might have solved this (admittedly simple) problem a bit different. I probably would have used the same provider interface but set it up in Application_Start with application root path. – Daniel Lidström Mar 11 '15 at 11:18
No, HttpContext.Current is not only available in the web project... If you reference a project which has GetAppDataPath(), it will always need to reference HttpContext.Current as well. I.e. if you use library A that uses library B, your application will need references to library A *and* B. – M. Mimpen Mar 11 '15 at 13:17
It is sometimes convenient to not access HttpContext directly, instead going through a level of indirection. Think unit tests for example. Testability is usually why I do things in this way. But I think you are incorrect regarding your statement. Only the interface needs to be shared between assemblies. That's the reason you can mock it for tests, i.e. you don't need HttpContext.Current for the tests. Sorry if I'm confusing things for you... – Daniel Lidström Mar 12 '15 at 12:19

Rudy Lattae · Answer 5 · 2010-11-16T21:38:38.217

Phil Haak has an example that I think is a bit more stable when dealing with paths with crazy "\" style directory separators. It also safely handles path concatenation. It comes for free in System.IO

var fileName = Path.GetFileName(file.FileName);
var path = Path.Combine(Server.MapPath("~/App_Data/uploads"), fileName);

However, you could also try "AppDomain.CurrentDomain.BaseDirector" instead of "Server.MapPath".

score 5 · Answer 6 · answered Jul 13 '16 at 08:02

5

string filePath = HttpContext.Current.Server.MapPath("~/folderName/filename.extension");

OR

string filePath = HttpContext.Server.MapPath("~/folderName/filename.extension");

answered Jul 13 '16 at 08:02

Dipak Delvadiya

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Although this code may help to solve the problem, providing additional context regarding why and/or how it answers the question would significantly improve its long-term value. Please edit your answer to add some explanation. – oɔɯǝɹ Jul 13 '16 at 21:45

score 1 · Answer 7 · answered Jul 21 '21 at 12:22

This way i got the hosting path.

using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;

namespace IHostingEnvironmentExample.Controllers
{
    public class HomeController : Controller
    {
        private IHostingEnvironment _env;
        public HomeController(IHostingEnvironment env)
        {
            _env = env;
        }
        public IActionResult Index()
        {
            var webRoot = _env.WebRootPath;
            var file = System.IO.Path.Combine(webRoot, "test.txt");
            System.IO.File.WriteAllText(file, "Hello World!");
            return View();
        }
    }
}

https://forums.asp.net/t/1696005.aspx?How+to+get+Local+Server+path+in+mvc

score 0 · Answer 8 · answered Dec 07 '17 at 05:22

string Index = i;
            string FileName = "Mutton" + Index + ".xml";
            XmlDocument xmlDoc = new XmlDocument();

            var path = Path.Combine(Server.MapPath("~/Content/FilesXML"), FileName);
            xmlDoc.Load(path); // Can use xmlDoc.LoadXml(YourString);

this is the best Solution to get the path what is exactly need for now

ASP.NET MVC - Find Absolute Path to the App_Data folder from Controller

8 Answers8

ASP.NET MVC1 -> MVC3

ASP.NET MVC4

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