ChatGPT解决这个技术问题 Extra ChatGPT

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

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?

L
Loudenvier

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");

HttpServerUtility.MapPath Method


@Cleiton Except that Url.Content gives a URL, not a server path.
for mvc4 it is only Server.MapPath()
The MVC4 way didn't work, I either had to use Current or Server.MapPath(...) as SeriousM mentioned.
Use System.Web.Hosting.HostingEnvironment.MapPath()
Calls to HttpContext.Current don't work in some situations where there isn't an HttpContext (application_start etc)
A
Alex from Jitbit
string path = AppDomain.CurrentDomain.GetData("DataDirectory").ToString();

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


Because it's not hardcoding the "App_Data" string. That can change in the future versions, or be different in Mono etc. etc.
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!
The blog post Pete refers to also talks about why using this might not be a great idea.
Not documented in MSDN, therefore should not be used.
Hard-coding another string instead of "App_Data" is not a "correct" way. Besides, there are no more app domains in .NET Core.
S
Simon_Weaver

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");

Server.MapPath() ultimately calls HostingEnvironment.MapPath(), see stackoverflow.com/questions/944219/…
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: docs.microsoft.com/en-us/dotnet/api/…
D
Daniel Lidström

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


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?
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.
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.
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...
R
Rudy Lattae

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".


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

OR

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

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.
佚名

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


S
Shahbaz Pirzada
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