无法从appsettings.json读取数据

Question

I'm sure I've got something basic wrong but I can't spot it, sorry. Stepping into the startup code suggests the appsettings.json is being correctly loaded, but the test class then gets null for the config class.

Startup:

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        var builder = new ConfigurationBuilder().AddJsonFile("appSettings.json");
        Configuration = builder.Build();
    }

    public IConfiguration Configuration { get; set; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc().AddSessionStateTempDataProvider();
        services.AddSession();

        services.Configure<EnvironmentConfig>(Configuration.GetSection("EnvironmentConfig"));
    }
}

ConfigTester:

public class ConfigTester
{
    private readonly IOptions<EnvironmentConfig> _environmentConfig;

    public ConfigTester(IOptions<EnvironmentConfig> environmentConfig)
    {
        _environmentConfig = environmentConfig;
    }

    public string ConfigName()
    {
        return _environmentConfig.Value.Name;         //_environmentConfig.Value is set, but Name is null
    }
}

EnvironmentConfig:

public class EnvironmentConfig
{
    public string Name;

}

appSettings.json:

{
  "Logging": {
    "IncludeScopes": false,
    "Debug": {
      "LogLevel": {
        "Default": "Warning"
      }
    },
    "Console": {
      "LogLevel": {
        "Default": "Warning"
      }
    }
  },
  "EnvironmentConfig": {
    "Name": "develop"
  }
}

What have I missed?

Answer 1

Add the following line in your ConfigureServices method before you configure your Options using serives.Configure<T>() . To use the Options feature you have to enable it.

services.AddOptions();

Answer 2

When using IServiceCollection.Configure , the ConfigurationBinder class that ends up doing the work of binding the values in your appSettings.json file to your EnvironmentConfig class only binds against properties . That means all you have to do is change your public field to a public property :

public class EnvironmentConfig
{
    public string Name { get; set; }
}