How to get values from appsettings.json in .NET Core?

 In .NET Core, you can access values from the appsettings.json file using the Configuration object, which is available through the IConfiguration interface.

Here are the steps to get values from appsettings.json in .NET Core:

1. Add a reference to the Microsoft.Extensions.Configuration.Json package in your project.

2. Create an appsettings.json file in your project root folder, and add your key-value pairs to it:

{
  "MySetting": "MyValue",
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=MyServer;Initial Catalog=MyDb;Integrated Security=True;"
  }
}

3. In your code, create an instance of IConfiguration by adding it to the dependency injection container. This can be done in the ConfigureServices method of the Startup class:

using Microsoft.Extensions.Configuration;

public class Startup
{
  public Startup(IConfiguration configuration)
  {
    Configuration = configuration;
  }

  public IConfiguration Configuration { get; }

  public void ConfigureServices(IServiceCollection services)
  {
    // Add IConfiguration to the service container
    services.AddSingleton(Configuration);
  }

  // ...
}

4. Use the GetValue extension method of IConfiguration to get the value of a setting:

string mySettingValue = Configuration.GetValue<string>("MySetting");
string connectionString = Configuration.GetConnectionString("DefaultConnection");

You can also bind a configuration section to a strongly-typed class using the Bind method:

public class ConnectionStrings
{
  public string DefaultConnection { get; set; }
}

ConnectionStrings connectionStrings = new ConnectionStrings();
Configuration.GetSection("ConnectionStrings").Bind(connectionStrings);

This approach allows you to access the settings through properties of the strongly-typed class, rather than using strings to access keys.