ASP.NET Core 1.0 ConfigurationBuilder().AddJsonFile(“appsettings.json”); 找不到文件

Question

So I've finally got round to looking at Core and I've fallen at the first hurdle. I'm following the Pluralsight ASP.NET Core Fundamentals course and I'm getting an exception when trying too add the appsettings.json file to the configuration builder.

public Startup()
{
    var builder = new ConfigurationBuilder()
        .AddJsonFile("appsettings.json");

    Configuration = builder.Build();
}

The error I'm getting is The configuration file 'appsettings.json' was not found and is not optional. But I have created the directly under my solution just like in the course video.

Answer 1

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json");

    Configuration = builder.Build();
}

This seems to do the trick. However unsure this is the proper way to do it. Kinda feels like a hack.

Answer 2

您需要添加以下包：

    "Microsoft.Extensions.Configuration.Json": "1.0.0"

Answer 3

Another way:

appsettings.json :

{
    "greeting": "A configurable hello, to you!"
}

Startup.cs :

using Microsoft.Extensions.Configuration; // for using IConfiguration
using System.IO; // for using Directory

public class Startup
{
    public IConfiguration Configuration { get; set; }

    public Startup()
    {
        var builder = new ConfigurationBuilder();
        builder.SetBasePath(Directory.GetCurrentDirectory());
        builder.AddJsonFile("appsettings.json");

        Configuration = builder.Build();
    }    
}

In the Configure method:

app.Run(async (context) =>
{
    // Don't use:
    // string greeting = Configuration["greeting"]; // null

    string greeting = Configuration.GetSection("greeting").Value;
    await context.Response.WriteAsync(greeting)
});

Answer 4

An alternative solution I found from this blog post works as well. It has the added benefit of not needing to modify the Startup.cs file's Startup method signature.

In the buildOptions section add copyToOutput with the name of the file.

{
  "version": "1.0.0-*",
  "buildOptions": {
    "emitEntryPoint": true,
    "copyToOutput": "appsettings.json"
  },
  .... The rest of the file goes here ....

Answer 5

Actually for this you need to provide root path from your environment variable so you need to pass IHostingEnvironment reference to provide root path:

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder()
                          .SetBasePath(env.ContentRootPath)
                          .AddJsonFile("appsettings.json");
    Configuration = builder.Build();
}

and if you can't find AddJsonFile method then you have to add using Microsoft.Extensions.Configuration.Json;

Answer 6

右键单击 appsettings.json -> 属性，然后确保将复制到输出目录设置为“始终复制”

Answer 7

In .NET Core 2.0, you would update the .csproj file to copy the JSON file to the output directory so that it can be accessed, like so:

<ItemGroup>
    <Folder Include="wwwroot\" />
    <None Include="appsettings.json" CopyToOutputDirectory="Always" />
</ItemGroup>

Answer 8

The answers that suggest adding .SetBasePath(env.ContentRootPath) in Startup.cs depend upon a prior step.

First , add the line .UseContentRoot(Directory.GetCurrentDirectory()) to your WebHostBuilder construction in Program.cs like so:

public class Program
{
    public static void Main(string[] args)
    {
        var config = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddEnvironmentVariables()
            .Build();

        var host = new WebHostBuilder()
            .UseConfiguration(config)
            .UseKestrel()
            .UseContentRoot(Directory.GetCurrentDirectory())
            .UseStartup<Startup>()
            .Build();

        host.Run();
    }
}

Then the following will work:

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json");

    Configuration = builder.Build();
}

Answer 9

If you have done anything with Project Debug Properties, then you may have inadvertently overwritten the starting directory:

Project -> Right-click -> Properties -> Debug -> Profile and then look at the entry in Working Directory .

The simplest is that it be blank.

Answer 10

你需要从Microsoft.Extensions中获取Configuration.Json包，或者只是将Microsoft.Extensions.Configuration.Json添加到y