Read solution data files ASP.Net Core

You can get the enviroment with Dependency Injection in your controller:

using Microsoft.AspNetCore.Hosting;
....

public class HomeController: Controller
{
   private IHostingEnvironment _env;

   public HomeController(IHostingEnvironment env)
   {
   _env = env;
   }   
...

Then you can get the wwwroot location in your actions: _env.WebRootPath

var owners =   System.IO.File.ReadAllLines(System.IO.Path.Combine(_env.WebRootPath,"File.txt"));

This has always worked for me locally and on IIS.

AppDomain.CurrentDomain.BaseDirectory

To access your file, you could simply do the following:

import System.IO
...
var owners = File.ReadAllLines(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "File.txt"))

in your controller you could take a dependency on IApplicationEnvironment and have it injected into the constructor then you can use it to establish the path to your file so your file can live in a folder within the project. In the example below "env" is the instance of IApplicationEnvironment

using Microsoft.Extensions.PlatformAbstractions;

var pathToFile = env.ApplicationBasePath 
   + Path.DirectorySeparatorChar.ToString() 
   + "yourfolder"
   + Path.DirectorySeparatorChar.ToString() 
   + "yourfilename.txt";

string fileContent;

using (StreamReader reader = File.OpenText(pathToFile))
{
    fileContent = reader.ReadToEnd();
}

ApplicationBasePath represents the applicationRootFolder

note that there also exists IHostingEnvironment which has the familiar .MapPath method, but it is for things stored below the wwwroot folder. You should only store things below the wwwroot folder that you want to serve with http requests so it is better to keep your list of strings in a different folder.

IApplicationEnvironment and IRuntimeEnvironment have been removed as of an announcement on github on 2016/04/26.

I replaced @JoeAudette's code with this

private readonly string pathToFile;

public UsersController(IHostingEnvironment env)
{
    pathToFile = env.ContentRootPath
       + Path.DirectorySeparatorChar.ToString()
       + "Data"
       + Path.DirectorySeparatorChar.ToString()
       + "users.json";
}

Where my .json file is located at src/WebApplication/Data/users.json

I then read/parse this data like so

private async Task<IEnumerable<User>> GetDataSet()
{
    string source = "";

    using (StreamReader SourceReader = File.OpenText(pathToFile))
    {
        source = await SourceReader.ReadToEndAsync();
    }

    return await Task.FromResult(JsonConvert.DeserializeObject<IEnumerable<User>>(source)));
}

This method worked for me locally and on Azure environment. It is taken from Joe's answer above

public static string ReadFile(string FileName)
    {
        try
        {
            using (StreamReader reader = File.OpenText(FileName))
            {
                string fileContent = reader.ReadToEnd();
                if (fileContent != null && fileContent != "")
                {
                    return fileContent;
                }
            }
        }
        catch (Exception ex)
        {
            //Log
            throw ex;
        }
        return null;
    }

And this is how invoked that method

string emailContent = ReadFile("./wwwroot/EmailTemplates/UpdateDetails.html");