Add WithChildRelationship methods for parent-child relationships

src/Aspire.Hosting/ResourceBuilderExtensions.cs

@@ -2239,6 +2239,70 @@ public static IResourceBuilder<T> WithParentRelationship<T>(
         return builder.WithRelationship(parent, KnownRelationshipTypes.Parent);
     }
 
+    /// <summary>
+    /// Adds a <see cref="ResourceRelationshipAnnotation"/> to the resource annotations to add a parent-child relationship.
+    /// </summary>
+    /// <typeparam name="T">The type of the resource.</typeparam>
+    /// <param name="builder">The resource builder.</param>
+    /// <param name="child">The child of <paramref name="builder"/>.</param>
+    /// <returns>A resource builder.</returns>
+    /// <remarks>
+    /// <para>
+    /// The <c>WithChildRelationship</c> method is used to add child relationships to the resource. Relationships are used to link
+    /// resources together in UI.
+    /// </para>
+    /// <example>
+    /// This example shows adding a relationship between two resources.
+    /// <code lang="C#">
+    /// var builder = DistributedApplication.CreateBuilder(args);
+    ///
+    /// var parameter = builder.AddParameter("parameter");
+    ///
+    /// var backend = builder.AddProject&lt;Projects.Backend&gt;("backend");
+    ///                      .WithChildRelationship(parameter);
+    /// </code>
+    /// </example>
+    /// </remarks>
+    public static IResourceBuilder<T> WithChildRelationship<T>(
+        this IResourceBuilder<T> builder,
+        IResourceBuilder<IResource> child) where T : IResource
+    {
+        child.WithRelationship(builder.Resource, KnownRelationshipTypes.Parent);
+        return builder;
+    }
+
+    /// <summary>
+    /// Adds a <see cref="ResourceRelationshipAnnotation"/> to the resource annotations to add a parent-child relationship.
+    /// </summary>
+    /// <typeparam name="T">The type of the resource.</typeparam>
+    /// <param name="builder">The resource builder.</param>
+    /// <param name="child">The child of <paramref name="builder"/>.</param>
+    /// <returns>A resource builder.</returns>
+    /// <remarks>
+    /// <para>
+    /// The <c>WithChildRelationship</c> method is used to add child relationships to the resource. Relationships are used to link
+    /// resources together in UI.
+    /// </para>
+    /// <example>
+    /// This example shows adding a relationship between two resources.
+    /// <code lang="C#">
+    /// var builder = DistributedApplication.CreateBuilder(args);
+    ///
+    /// var parameter = builder.AddParameter("parameter");
+    ///
+    /// var backend = builder.AddProject&lt;Projects.Backend&gt;("backend");
+    ///                     .WithChildRelationship(parameter.Resource);
+    /// </code>
+    /// </example>
+    /// </remarks>
+    public static IResourceBuilder<T> WithChildRelationship<T>(
+         this IResourceBuilder<T> builder,
+         IResource child) where T : IResource
+    {
+        var childBuilder = builder.ApplicationBuilder.CreateResourceBuilder(child);
+        return builder.WithChildRelationship(childBuilder);
+    }
+
     /// <summary>
     /// Specifies the icon to use when displaying the resource in the dashboard.
     /// </summary>

tests/Aspire.Hosting.Tests/Orchestrator/ApplicationOrchestratorTests.cs

@@ -350,10 +350,10 @@ public async Task GrandChildResourceWithConnectionString()
 
         var parentResource = builder.AddResource(new ParentResourceWithConnectionString("parent"));
         var childResource = builder.AddResource(
-            new ChildResourceWithConnectionString("child", new Dictionary<string, string> { {"Namespace", "ns"} }, parentResource.Resource)
+            new ChildResourceWithConnectionString("child", new Dictionary<string, string> { { "Namespace", "ns" } }, parentResource.Resource)
         );
         var grandChildResource = builder.AddResource(
-            new ChildResourceWithConnectionString("grand-child", new Dictionary<string, string> { {"Database", "db"} }, childResource.Resource)
+            new ChildResourceWithConnectionString("grand-child", new Dictionary<string, string> { { "Database", "db" } }, childResource.Resource)
         );
 
         await using var app = builder.Build();
@@ -589,10 +589,10 @@ await events.PublishAsync(new OnResourceChangedContext(
 
         // Parent should have the new state
         Assert.Equal(KnownResourceStates.FailedToStart, parentState);
-        
+
         // Child container (has own lifetime) should NOT receive parent state
         Assert.NotEqual(KnownResourceStates.Running, childContainerState);
-        
+
         // Custom child (does not have own lifetime) SHOULD receive parent state
         Assert.Equal(KnownResourceStates.FailedToStart, customChildState);
     }
@@ -635,11 +635,171 @@ await events.PublishAsync(new OnResourceChangedContext(
 
         // Parent should have the new state
         Assert.Equal(KnownResourceStates.FailedToStart, parentState);
-        
+
         // Child project (has own lifetime) should NOT receive parent state
         Assert.NotEqual(KnownResourceStates.Running, childProjectState);
-        
+
         // Custom child (does not have own lifetime) SHOULD receive parent state
         Assert.Equal(KnownResourceStates.FailedToStart, customChildState);
     }
+
+    [Fact]
+    public async Task WithChildRelationshipUsingResourceBuilderSetsParentPropertyCorrectly()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        var parent = builder.AddContainer("parent", "image");
+        var child = builder.AddContainer("child", "image");
+        var child2 = builder.AddContainer("child2", "image");
+
+        parent.WithChildRelationship(child)
+              .WithChildRelationship(child2);
+
+        using var app = builder.Build();
+        var distributedAppModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var events = new DcpExecutorEvents();
+        var resourceNotificationService = ResourceNotificationServiceTestHelpers.Create();
+
+        var appOrchestrator = CreateOrchestrator(distributedAppModel, notificationService: resourceNotificationService, dcpEvents: events);
+        await appOrchestrator.RunApplicationAsync();
+
+        string? parentResourceId = null;
+        string? childParentResourceId = null;
+        string? child2ParentResourceId = null;
+        var watchResourceTask = Task.Run(async () =>
+        {
+            await foreach (var item in resourceNotificationService.WatchAsync())
+            {
+                if (item.Resource == parent.Resource)
+                {
+                    parentResourceId = item.ResourceId;
+                }
+                else if (item.Resource == child.Resource)
+                {
+                    childParentResourceId = item.Snapshot.Properties.SingleOrDefault(p => p.Name == KnownProperties.Resource.ParentName)?.Value?.ToString();
+                }
+                else if (item.Resource == child2.Resource)
+                {
+                    child2ParentResourceId = item.Snapshot.Properties.SingleOrDefault(p => p.Name == KnownProperties.Resource.ParentName)?.Value?.ToString();
+                }
+
+                if (parentResourceId != null && childParentResourceId != null && child2ParentResourceId != null)
+                {
+                    return;
+                }
+            }
+        });
+
+        await events.PublishAsync(new OnResourcesPreparedContext(CancellationToken.None));
+
+        await watchResourceTask.DefaultTimeout();
+
+        Assert.Equal(parentResourceId, childParentResourceId);
+        Assert.Equal(parentResourceId, child2ParentResourceId);
+    }
+
+    [Fact]
+    public async Task WithChildRelationshipUsingResourceSetsParentPropertyCorrectly()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        var parent = builder.AddContainer("parent", "image");
+        var child = builder.AddContainer("child", "image");
+        var child2 = builder.AddContainer("child2", "image");
+
+        parent.WithChildRelationship(child.Resource)
+              .WithChildRelationship(child2.Resource);
+
+        using var app = builder.Build();
+        var distributedAppModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var events = new DcpExecutorEvents();
+        var resourceNotificationService = ResourceNotificationServiceTestHelpers.Create();
+
+        var appOrchestrator = CreateOrchestrator(distributedAppModel, notificationService: resourceNotificationService, dcpEvents: events);
+        await appOrchestrator.RunApplicationAsync();
+
+        string? parentResourceId = null;
+        string? childParentResourceId = null;
+        string? child2ParentResourceId = null;
+        var watchResourceTask = Task.Run(async () =>
+        {
+            await foreach (var item in resourceNotificationService.WatchAsync())
+            {
+                if (item.Resource == parent.Resource)
+                {
+                    parentResourceId = item.ResourceId;
+                }
+                else if (item.Resource == child.Resource)
+                {
+                    childParentResourceId = item.Snapshot.Properties.SingleOrDefault(p => p.Name == KnownProperties.Resource.ParentName)?.Value?.ToString();
+                }
+                else if (item.Resource == child2.Resource)
+                {
+                    child2ParentResourceId = item.Snapshot.Properties.SingleOrDefault(p => p.Name == KnownProperties.Resource.ParentName)?.Value?.ToString();
+                }
+
+                if (parentResourceId != null && childParentResourceId != null && child2ParentResourceId != null)
+                {
+                    return;
+                }
+            }
+        });
+
+        await events.PublishAsync(new OnResourcesPreparedContext(CancellationToken.None));
+
+        await watchResourceTask.DefaultTimeout();
+
+        Assert.Equal(parentResourceId, childParentResourceId);
+        Assert.Equal(parentResourceId, child2ParentResourceId);
+    }
+
+    [Fact]
+    public async Task WithChildRelationshipWorksWithProjects()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        var parentProject = builder.AddProject<ProjectA>("parent-project");
+        var childProject = builder.AddProject<ProjectB>("child-project");
+
+        parentProject.WithChildRelationship(childProject);
+
+        using var app = builder.Build();
+        var distributedAppModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var events = new DcpExecutorEvents();
+        var resourceNotificationService = ResourceNotificationServiceTestHelpers.Create();
+
+        var appOrchestrator = CreateOrchestrator(distributedAppModel, notificationService: resourceNotificationService, dcpEvents: events);
+        await appOrchestrator.RunApplicationAsync();
+
+        string? parentProjectResourceId = null;
+        string? childProjectParentResourceId = null;
+        var watchResourceTask = Task.Run(async () =>
+        {
+            await foreach (var item in resourceNotificationService.WatchAsync())
+            {
+                if (item.Resource == parentProject.Resource)
+                {
+                    parentProjectResourceId = item.ResourceId;
+                }
+                else if (item.Resource == childProject.Resource)
+                {
+                    childProjectParentResourceId = item.Snapshot.Properties.SingleOrDefault(p => p.Name == KnownProperties.Resource.ParentName)?.Value?.ToString();
+                }
+
+                if (parentProjectResourceId != null && childProjectParentResourceId != null)
+                {
+                    return;
+                }
+            }
+        });
+
+        await events.PublishAsync(new OnResourcesPreparedContext(CancellationToken.None));
+
+        await watchResourceTask.DefaultTimeout();
+
+        Assert.Equal(parentProjectResourceId, childProjectParentResourceId);
+    }
 }

tests/Aspire.Hosting.Tests/Orchestrator/RelationshipEvaluatorTests.cs

@@ -44,6 +44,97 @@ public void HandlesNestedChildren()
         Assert.Empty(parentChildLookup[grandChildWithAnnotationsResource.Resource]);
     }
 
+    [Fact]
+    public void WithChildRelationshipUsingResourceBuilderCreatesCorrectParentChildLookup()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        var parentResource = builder.AddContainer("parent", "image");
+        var child1Resource = builder.AddContainer("child1", "image");
+        var child2Resource = builder.AddContainer("child2", "image");
+
+        parentResource.WithChildRelationship(child1Resource)
+                     .WithChildRelationship(child2Resource);
+
+        using var app = builder.Build();
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var parentChildLookup = RelationshipEvaluator.GetParentChildLookup(appModel);
+        Assert.Equal(1, parentChildLookup.Count);
+
+        Assert.Collection(parentChildLookup[parentResource.Resource],
+            x => Assert.Equal(child1Resource.Resource, x),
+            x => Assert.Equal(child2Resource.Resource, x));
+    }
+
+    [Fact]
+    public void WithChildRelationshipUsingResourceCreatesCorrectParentChildLookup()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        var parentResource = builder.AddContainer("parent", "image");
+        var child1Resource = builder.AddContainer("child1", "image");
+        var child2Resource = builder.AddContainer("child2", "image");
+
+        parentResource.WithChildRelationship(child1Resource.Resource)
+                     .WithChildRelationship(child2Resource.Resource);
+
+        using var app = builder.Build();
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var parentChildLookup = RelationshipEvaluator.GetParentChildLookup(appModel);
+        Assert.Equal(1, parentChildLookup.Count);
+
+        Assert.Collection(parentChildLookup[parentResource.Resource],
+            x => Assert.Equal(child1Resource.Resource, x),
+            x => Assert.Equal(child2Resource.Resource, x));
+    }
+
+    [Fact]
+    public void WithChildRelationshipAndWithParentRelationshipWorkTogether()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        var parentResource = builder.AddContainer("parent", "image");
+        var child1Resource = builder.AddContainer("child1", "image");
+        var child2Resource = builder.AddContainer("child2", "image")
+            .WithParentRelationship(parentResource);
+
+        parentResource.WithChildRelationship(child1Resource);
+
+        using var app = builder.Build();
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var parentChildLookup = RelationshipEvaluator.GetParentChildLookup(appModel);
+        Assert.Equal(1, parentChildLookup.Count);
+
+        Assert.Collection(parentChildLookup[parentResource.Resource],
+            x => Assert.Equal(child1Resource.Resource, x),
+            x => Assert.Equal(child2Resource.Resource, x));
+    }
+
+    [Fact]
+    public void WithChildRelationshipHandlesNestedRelationships()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        var grandParentResource = builder.AddContainer("grandparent", "image");
+        var parentResource = builder.AddContainer("parent", "image");
+        var childResource = builder.AddContainer("child", "image");
+
+        grandParentResource.WithChildRelationship(parentResource);
+        parentResource.WithChildRelationship(childResource);
+
+        using var app = builder.Build();
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var parentChildLookup = RelationshipEvaluator.GetParentChildLookup(appModel);
+        Assert.Equal(2, parentChildLookup.Count);
+
+        Assert.Single(parentChildLookup[grandParentResource.Resource], parentResource.Resource);
+        Assert.Single(parentChildLookup[parentResource.Resource], childResource.Resource);
+    }
+
     private sealed class CustomChildResource(string name, IResource parent) : Resource(name), IResourceWithParent
     {
         public IResource Parent => parent;