How to organize your dependencies in .NET

In the world of .NET development, it’s a common practice to establish registrations for dependencies, ranging from basic services to third-party components obtained through NuGet packages.

1/ Inline Dependency Registration

Consider a straightforward example of dependency registration. Below is an illustration of how dependencies would be registered in a Program.cs file.

builder.Services.AddScoped<IUserService, UserService>();
builder.Services.AddScoped<IRoleService, RoleService>();
builder.Services.AddScoped<AddSecurityHeader>();
builder.Services.AddScoped<HttpClient>();
builder.Services.AddScoped<IValidator<CreateUserCommand>, CreateUserCommandValidator>();

2/ Extension Method Dependency Registration

The previous approach is suitable but becomes less efficient as the number of dependencies increases.

A more effective strategy involves relocating these dependencies into an extension method and then invoking that extension method within the Program file.

public static IServiceCollection AddApplication Dependencies( this IServiceCollection services)
{
services.AddScoped<IUserService, UserService>();
services.AddScoped<IRoleService, RoleService>();
services.AddScoped<AddSecurityHeader>();
services.AddScoped<HttpClient>();
services.AddScoped<IValidator<CreateUserCommad>, CreateUserCommadValidator>();
return services;
}

Add in Program

builder.Services.AddApplicationDependencies();

3/ Modularized Dependency Registration

I prefer to create distinct extension methods for each concern.

Then, I consolidate the invocation of these methods into a single method, and only this method is called in the Program file.

This ensures a more organized and modular approach to dependency registration.

public static IServiceCollection AddApiDependencies(this IServiceCollection services)
{
    services.AddServices();
    services.AddDelegateHandlers();
    services.AddValidators();
    return services;
}
public static IServiceCollection AddServices(this IServiceCollection services)
{
    services.AddScoped<IUserService, UserService>();
    services.AddScoped<IRoleService, RoleService>();
    return services;
}
public static IServiceCollection AddDelegateHandlers(this IServiceCollection services)
{
    services.AddScoped<AddSecurityHeader>();
    return services;
}
public static IServiceCollection AddValidators(this IServiceCollection services)
{
    services.AddScoped<IValidator<CreateUserCommand>, CreateUserCommandValidator>();
    return services;
}

Add in Program file

builder.Services.AddApiDependencies();

This way dependencies becomes :

• More clean

• Easy to manage