Infer Entity Resolvers with Patterns

src/HotChocolate/Core/src/Abstractions/Execution/ISourceStream.cs

@@ -11,5 +11,5 @@ public interface ISourceStream : IAsyncDisposable
     /// <summary>
     /// Reads the subscription result from the pub/sub system.
     /// </summary>
-    IAsyncEnumerable<object> ReadEventsAsync();
+    IAsyncEnumerable<object?> ReadEventsAsync();
 }

src/HotChocolate/Core/src/Execution/Processing/SubscriptionExecutor.Subscription.cs

@@ -362,15 +362,15 @@ public IAsyncEnumerator<IQueryResult> GetAsyncEnumerator(
 
     private sealed class SubscriptionEnumerator : IAsyncEnumerator<IQueryResult>
     {
-        private readonly IAsyncEnumerator<object> _eventEnumerator;
+        private readonly IAsyncEnumerator<object?> _eventEnumerator;
         private readonly Func<object, Task<IQueryResult>> _onEvent;
         private readonly Subscription _subscription;
         private readonly IExecutionDiagnosticEvents _diagnosticEvents;
         private readonly CancellationToken _requestAborted;
         private bool _disposed;
 
         public SubscriptionEnumerator(
-            IAsyncEnumerator<object> eventEnumerator,
+            IAsyncEnumerator<object?> eventEnumerator,
             Func<object, Task<IQueryResult>> onEvent,
             Subscription subscription,
             IExecutionDiagnosticEvents diagnosticEvents,

src/HotChocolate/Fusion/src/Composition/Entities/EntityMetadata.cs

@@ -10,7 +10,7 @@ internal sealed class EntityMetadata
     /// <summary>
     /// Gets the list of entity resolvers associated with this entity.
     /// </summary>
-    public List<EntityResolver> EntityResolvers { get; } = new();
+    public EntityResolversCollection EntityResolvers { get; } = new();
 
     /// <summary>
     /// Gets fields that have dependencies on other fields.
@@ -37,4 +37,4 @@ public override string ToString()
 
         return sb.ToString();
     }
-}
+}

src/HotChocolate/Fusion/src/Composition/Entities/EntityResolversCollection.cs

@@ -0,0 +1,96 @@
+using System.Collections;
+using System.Text;
+using HotChocolate.Language;
+
+namespace HotChocolate.Fusion.Composition;
+
+internal class EntityResolversCollection : ICollection<EntityResolver>
+{
+    private readonly List<EntityResolver> _resolvers = new();
+    private readonly Dictionary<ResolverKey, EntityResolver> _map = new();
+
+    public int Count => _resolvers.Count;
+
+    public bool IsReadOnly => false;
+
+    public bool Contains(EntityResolver item)
+        => _map.ContainsKey(item);
+
+    public void Add(EntityResolver item)
+    {
+        _map.Add(item, item);
+        _resolvers.Add(item);
+    }
+
+    public bool TryAdd(EntityResolver item)
+    {
+        if (_map.TryAdd(item, item))
+        {
+            _resolvers.Add(item);
+            return true;
+        }
+
+        return false;
+    }
+
+    public bool Remove(EntityResolver item)
+    {
+        if(_map.TryGetValue(item, out var resolver))
+        {
+            _map.Remove(item);
+            _resolvers.Remove(resolver);
+            return true;
+        }
+
+        return false;
+    }
+
+    public void Clear()
+    {
+        _resolvers.Clear();
+        _map.Clear();
+    }
+
+    public void CopyTo(EntityResolver[] array, int arrayIndex)
+        => _resolvers.CopyTo(array, arrayIndex);
+
+    public IEnumerator<EntityResolver> GetEnumerator()
+        => _resolvers.GetEnumerator();
+
+    IEnumerator IEnumerable.GetEnumerator()
+        => GetEnumerator();
+
+    private readonly record struct ResolverKey(string SubgraphName, SelectionSetNode SelectionSet)
+    {
+        public bool Equals(ResolverKey? other)
+        {
+            if (other is null)
+            {
+                return false;
+            }
+
+            return string.Equals(SubgraphName, other.Value.SubgraphName) &&
+                SyntaxComparer.BySyntax.Equals(SelectionSet, other.Value.SelectionSet);
+        }
+
+        public override int GetHashCode()
+            => HashCode.Combine(SubgraphName, SyntaxComparer.BySyntax.GetHashCode(SelectionSet));
+
+        private bool PrintMembers(StringBuilder builder)
+        {
+            builder.AppendLine(SubgraphName);
+            builder.AppendLine(SelectionSet.ToString());
+            return true;
+        }
+
+        public override string ToString()
+        {
+            var builder = new StringBuilder();
+            PrintMembers(builder);
+            return builder.ToString();
+        }
+
+        public static implicit operator ResolverKey(EntityResolver value)
+            => new(value.SubgraphName, value.SelectionSet); 
+    }
+}

src/HotChocolate/Fusion/src/Composition/Extensions/SchemaExtensions.cs

@@ -33,7 +33,7 @@ public static string CreateVariableName(
         context.Name.Insert(0, type.Name);
         return context.Name.ToString();
     }
-
+    
     public static VariableDefinition CreateVariableField(
         this InputField argument,
         IsDirective directive,
@@ -85,4 +85,4 @@ private sealed class FieldVariableNameContext : ISyntaxVisitorContext
     {
         public StringBuilder Name { get; } = new();
     }
-}
+}

src/HotChocolate/Fusion/src/Composition/FusionGraphComposer.cs

@@ -35,6 +35,7 @@ public FusionGraphComposer(
             new IEntityEnricher[]
             {
                 new RefResolverEntityEnricher(),
+                new PatternEntityEnricher(),
                 new RequireEnricher(),
                 new NodeEntityEnricher()
             },

src/HotChocolate/Fusion/src/Composition/Pipeline/Enrichers/NodeEntityEnricher.cs

@@ -105,7 +105,7 @@ private static void ResolveWithNode(
                 _idVariable.WithVariable(varNode)));
 
         // Add the new EntityResolver to the entity metadata
-        entity.Metadata.EntityResolvers.Add(resolver);
+        entity.Metadata.EntityResolvers.TryAdd(resolver);
     }
 
     private static void ResolveWithNodes(
@@ -159,6 +159,6 @@ private static void ResolveWithNodes(
                 _idsVariable.WithVariable(varNode)));
 
         // Add the new EntityResolver to the entity metadata
-        entity.Metadata.EntityResolvers.Add(resolver);
+        entity.Metadata.EntityResolvers.TryAdd(resolver);
     }
 }