Apq.Cfg/docs/site/en/guide/dependency-injection.md

Dependency Injection

Apq.Cfg integrates seamlessly with ASP.NET Core dependency injection.

Basic Integration

var builder = WebApplication.CreateBuilder(args);

// Register Apq.Cfg
builder.Services.AddApqCfg(cfg => cfg
    .AddJson("config.json", level: 0, writeable: false)
    .AddEnvironmentVariables(level: 1, prefix: "APP_"));

var app = builder.Build();

Inject ICfgRoot

public class MyService
{
    private readonly ICfgRoot _cfg;

    public MyService(ICfgRoot cfg)
    {
        _cfg = cfg;
    }

    public string GetAppName()
    {
        return _cfg.Get("App:Name") ?? "DefaultApp";
    }
}

Options Pattern

Configure Options

public class DatabaseOptions
{
    public string Host { get; set; } = "localhost";
    public int Port { get; set; } = 5432;
    public string Name { get; set; } = "";
}

builder.Services.AddApqCfg(cfg => cfg
    .AddJson("config.json", level: 0, writeable: false));

builder.Services.ConfigureApqCfg<DatabaseOptions>("Database");

Use Options

public class DatabaseService
{
    private readonly DatabaseOptions _options;

    public DatabaseService(IOptions<DatabaseOptions> options)
    {
        _options = options.Value;
    }

    public string GetConnectionString()
    {
        return $"Host={_options.Host};Port={_options.Port};Database={_options.Name}";
    }
}

IConfiguration Compatibility

// Apq.Cfg also registers IConfiguration
public class LegacyService
{
    private readonly IConfiguration _config;

    public LegacyService(IConfiguration config)
    {
        _config = config;
    }
}

Scoped Configuration

For request-scoped configuration:

builder.Services.AddScoped<RequestConfig>(sp =>
{
    var cfg = sp.GetRequiredService<ICfgRoot>();
    return new RequestConfig
    {
        Timeout = cfg.Get<int>("Request:Timeout")
    };
});

Next Steps

• Best Practices - Configuration best practices
• Dynamic Reload - Hot reload with DI