How to get setting from appsettings.json

Question

Hi all

I am working in a Web API project. I have a class library in the solution. In this library I want to get a setting from the appSettings.json.

The only options I have seen so far seem to revolve around passing the IConfiguration object down from the web api. This is annoying.

Is there a way to just get the configuration in the class library without passing it in?

It used to be easy with the previous configuration settings - can't understand why it is so hard now...

Thanks

Answer 1

Hi @William Buchanan ,

In the Class Library, you can install the Microsoft.Extensions.Configuration and Microsoft.Extensions.Configuration.Json package via NuGet.

Then refer to the following code to add the appSettings.json file and read the configuration.

public interface IDataRepository  
{  
    string GetConnection();  
}  

public class DataRepository : IDataRepository  
{  
    private readonly IConfiguration _config;  
    public DataRepository(IConfiguration configuration)  
    {  
        _config= configuration;  
    }  
    public string GetConnection()  
    {  
        string c = Directory.GetCurrentDirectory();  
        IConfigurationRoot configuration = new ConfigurationBuilder().SetBasePath(c).AddJsonFile("appSettings.json").Build();  
        string connectionStringIs = configuration.GetConnectionString("WebApplication1Context");  
        return connectionStringIs;  
    }  
}  

In the API application, add the Class Library reference, and register the above repository.

builder.Services.AddScoped<IDataRepository, DataRepository>();  

In the appSetting.json file, add the connection string like this:

"ConnectionStrings": {  
 "WebApplication1Context": "Server=(localdb)\\mssqllocaldb;Database=WebApplication1;Trusted_Connection=True;MultipleActiveResultSets=true"   
  },  

Then, in the API controller, call the Class Library method:

[ApiController]  
public class UsersController : ControllerBase  
{  
    private readonly IDataRepository _repo;  
    public UsersController(IDataRepository dataRepository)  
    {  
        _repo = dataRepository;  
    }  

    [HttpGet]  
    [Route("getconnectionstring")]  
    public IActionResult GetCurrentUserGroups()  
    {  
        var connection = _repo.GetConnection();  
        return Ok(connection);  
    }   
}  

The result as below:

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Best regards,
Dillion

Answer 2

it considered a bad practice to tie a library to a configuration system and DI should be used instead. if you want static setup, define a config poco object for your library, and make it a static, that can be set in startup.