Dependency Injection — Animate | AI Wisdom

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🎞 ANIMATE · Mode 3 of 5 · +100 XP— .NET Dependency Injection
📋Register
⚙️Lifetimes
🔄Factory
✅Inject
🎯 Next: Test →
Step 1 / 4
Speed
Register Services
Add services to IServiceCollection with AddSingleton/Scoped/Transient💡 Analogy
Like a staffing agency register — you list the roles and which person fills each role.
Services are registered in Program.cs. The DI container knows which concrete class to create when an interface is requested.
Console Output
> ICacheService → RedisCacheService (Singleton)
> IOrderRepository → SqlOrderRepository (Scoped)
> IEmailBuilder → HtmlEmailBuilder (Transient)
●DependencyInjection.cs
Register ServicesL1–13
1// Registration in Program.cs
2var builder = WebApplication.CreateBuilder(args);
3 
4// Singleton: one instance for the app lifetime
5builder.Services.AddSingleton<IConfiguration>(builder.Configuration);
6builder.Services.AddSingleton<ICacheService, RedisCacheService>();
7 
8// Scoped: one instance per HTTP request
9builder.Services.AddScoped<IOrderRepository, SqlOrderRepository>();
10builder.Services.AddScoped<IUnitOfWork, EfCoreUnitOfWork>();
11 
12// Transient: new instance every time it's requested
13builder.Services.AddTransient<IEmailBuilder, HtmlEmailBuilder>();
14builder.Services.AddTransient<IValidator<Order>, OrderValidator>();
15 
16// Factory registration for conditional dependencies
17builder.Services.AddTransient<IPaymentGateway>(sp =>
18{
19    var config = sp.GetRequiredService<IConfiguration>();
20    return config["Payment:Provider"] == "stripe"
21        ? new StripeGateway(config["Payment:StripeKey"])
22        : new PayPalGateway(config["Payment:PayPalKey"]);
23});
24 
25var app = builder.Build();
26 
27// Usage: constructor injection
28public class OrderService(
29    IOrderRepository orders,    // Scoped: same instance in this request
30    ICacheService cache,        // Singleton: shared across all requests
31    IEmailBuilder emailBuilder  // Transient: fresh every time
32)
33{
34    public async Task ProcessAsync(Guid orderId)
35    {
36        var order = await orders.GetAsync(orderId); // injected repo
37        await cache.SetAsync($"order:{orderId}", order); // injected cache
38    }
39}
39 lines
Timeline — 4 Steps
Register Services
Add services to IServiceCollection with AddSingleton/Scoped/Transient💡 Analogy
Like a staffing agency register — you list the roles and which person fills each role.
Services are registered in Program.cs. The DI container knows which concrete class to create when an interface is requested.
Console Output
> ICacheService → RedisCacheService (Singleton)
> IOrderRepository → SqlOrderRepository (Scoped)
> IEmailBuilder → HtmlEmailBuilder (Transient)

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Discussion

Add services to IServiceCollection with AddSingleton/Scoped/Transient

💡 Analogy

Like a staffing agency register — you list the roles and which person fills each role.

Services are registered in Program.cs. The DI container knows which concrete class to create when an interface is requested.

Console Output

> ICacheService → RedisCacheService (Singleton)
> IOrderRepository → SqlOrderRepository (Scoped)
> IEmailBuilder → HtmlEmailBuilder (Transient)

Add services to IServiceCollection with AddSingleton/Scoped/Transient

💡 Analogy

Like a staffing agency register — you list the roles and which person fills each role.

Services are registered in Program.cs. The DI container knows which concrete class to create when an interface is requested.

Console Output

> ICacheService → RedisCacheService (Singleton)
> IOrderRepository → SqlOrderRepository (Scoped)
> IEmailBuilder → HtmlEmailBuilder (Transient)