#4284 Support DI-backed composite projections

src/DaemonTests/Composites/Feature_4284_composite_projection_with_services.cs

@@ -0,0 +1,147 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using JasperFx.Core;
+using JasperFx.Events;
+using Marten;
+using Marten.Events.Aggregation;
+using Marten.Events.Projections;
+using Marten.Testing.Harness;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Shouldly;
+using Xunit;
+
+namespace DaemonTests.Composites;
+
+public class Feature_4284_composite_projection_with_services
+{
+    [Fact]
+    public async Task can_use_scoped_services_in_projection_registered_under_composite()
+    {
+        using var host = await Host.CreateDefaultBuilder()
+            .ConfigureServices(services =>
+            {
+                services.AddScoped<ICompositePriceLookup, CompositePriceLookup>();
+
+                services.AddMarten(opts =>
+                    {
+                        opts.Connection(ConnectionSource.ConnectionString);
+                        opts.DatabaseSchemaName = "feature_4284_net" + Environment.Version.Major;
+                        opts.Projections.CompositeProjectionFor("Feature4284Products", projection =>
+                        {
+                            projection.AddProjectionWithServices<CompositeProductProjection>(ServiceLifetime.Scoped);
+                            projection.AddProjectionWithServices<CompositeProductMetricProjection>(ServiceLifetime.Scoped);
+                        });
+                    })
+                    .ApplyAllDatabaseChangesOnStartup();
+            })
+            .StartAsync();
+
+        var store = host.Services.GetRequiredService<IDocumentStore>();
+        await store.Advanced.Clean.CompletelyRemoveAllAsync();
+
+        await using var session = store.LightweightSession();
+        var streamId = session.Events.StartStream<CompositeProduct>(
+            new CompositeProductRegistered("Ankle Socks", "Socks")).Id;
+        await session.SaveChangesAsync();
+
+        using var daemon = await store.BuildProjectionDaemonAsync();
+        await daemon.StartAllAsync();
+        await daemon.WaitForNonStaleData(10.Seconds());
+        await daemon.StopAllAsync();
+
+        var product = await session.LoadAsync<CompositeProduct>(streamId);
+        product.ShouldNotBeNull();
+        product.Name.ShouldBe("Ankle Socks");
+        product.Category.ShouldBe("Socks");
+        product.Price.ShouldBe(12.5);
+
+        var metric = await session.LoadAsync<CompositeProductMetric>(streamId);
+        metric.ShouldNotBeNull();
+        metric.Price.ShouldBe(12.5);
+    }
+}
+
+public interface ICompositePriceLookup
+{
+    double PriceFor(string category);
+}
+
+public class CompositePriceLookup: ICompositePriceLookup
+{
+    public double PriceFor(string category)
+    {
+        return category == "Socks" ? 12.5 : 5;
+    }
+}
+
+public class CompositeProduct
+{
+    public Guid Id { get; set; }
+    public double Price { get; set; }
+    public string Category { get; set; }
+    public string Name { get; set; }
+}
+
+public record CompositeProductRegistered(string Name, string Category);
+
+public class CompositeProductMetric
+{
+    public Guid Id { get; set; }
+    public double Price { get; set; }
+}
+
+public class CompositeProductProjection: SingleStreamProjection<CompositeProduct, Guid>
+{
+    private readonly ICompositePriceLookup _lookup;
+
+    public CompositeProductProjection(ICompositePriceLookup lookup)
+    {
+        _lookup = lookup;
+        Name = "Feature4284Product";
+    }
+
+    public override CompositeProduct Evolve(CompositeProduct snapshot, Guid id, IEvent e)
+    {
+        snapshot ??= new CompositeProduct { Id = id };
+
+        if (e.Data is CompositeProductRegistered registered)
+        {
+            snapshot.Price = _lookup.PriceFor(registered.Category);
+            snapshot.Name = registered.Name;
+            snapshot.Category = registered.Category;
+        }
+
+        return snapshot;
+    }
+}
+
+public class CompositeProductMetricProjection: IProjection
+{
+    private readonly ICompositePriceLookup _lookup;
+
+    public CompositeProductMetricProjection(ICompositePriceLookup lookup)
+    {
+        _lookup = lookup;
+    }
+
+    public Task ApplyAsync(IDocumentOperations operations, IReadOnlyList<IEvent> events,
+        CancellationToken cancellation)
+    {
+        foreach (var e in events)
+        {
+            if (e.Data is CompositeProductRegistered registered)
+            {
+                operations.Store(new CompositeProductMetric
+                {
+                    Id = e.StreamId,
+                    Price = _lookup.PriceFor(registered.Category)
+                });
+            }
+        }
+
+        return Task.CompletedTask;
+    }
+}