[Fusion] Support abstract lookups

src/HotChocolate/Fusion-vnext/src/Fusion.Composition/Extensions/MutableObjectTypeDefinitionExtensions.cs

@@ -34,6 +34,8 @@ public static IEnumerable<IDirective> GetFusionLookupDirectives(
                 .ToList();
 
         // To use an abstract lookup, the type must exist in the source schema.
+        // TODO: For abstract lookups we also need to validate that the type
+        //       is part of the abstract type's possible types in the specific source schema.
         if (type.ExistsInSchema(schemaName))
         {
             // Interface lookups.

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Collections/SourceInterfaceTypeCollection.cs

@@ -3,16 +3,11 @@
 
 namespace HotChocolate.Fusion.Types.Collections;
 
-public class SourceInterfaceTypeCollection
-    : SourceMemberCollection<SourceInterfaceType>
+public class SourceInterfaceTypeCollection(IEnumerable<SourceInterfaceType> members)
+    : SourceMemberCollection<SourceInterfaceType>(members)
     , ISourceComplexTypeCollection<SourceInterfaceType>
     , ISourceComplexTypeCollection<ISourceComplexType>
 {
-    public SourceInterfaceTypeCollection(IEnumerable<SourceInterfaceType> members)
-        : base(members)
-    {
-    }
-
     ISourceComplexType ISourceMemberCollection<ISourceComplexType>.this[string schemaName]
         => this[schemaName];
 
@@ -22,12 +17,9 @@ public ImmutableArray<SourceInterfaceType> Types
     ImmutableArray<ISourceComplexType> ISourceComplexTypeCollection<ISourceComplexType>.Types
         => [.. Members];
 
-    public bool TryGetType(string schemaName, [NotNullWhen(true)] out SourceInterfaceType? type)
-        => TryGetMember(schemaName, out type);
-
-    public bool TryGetType(string schemaName, [NotNullWhen(true)] out ISourceComplexType? type)
+    public bool TryGetMember(string schemaName, [NotNullWhen(true)] out ISourceComplexType? type)
     {
-        if (TryGetMember(schemaName, out var member))
+        if (base.TryGetMember(schemaName, out var member))
         {
             type = member;
             return true;

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Collections/SourceMemberCollection.cs

@@ -11,7 +11,7 @@ public class SourceMemberCollection<TMember>
 {
     private readonly FrozenDictionary<string, TMember> _members;
 
-    protected SourceMemberCollection(IEnumerable<TMember> members)
+    public SourceMemberCollection(IEnumerable<TMember> members)
     {
         _members = members.ToFrozenDictionary(t => t.SchemaName);
     }

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Collections/SourceObjectTypeCollection.cs

@@ -17,12 +17,9 @@ public ImmutableArray<SourceObjectType> Types
     ImmutableArray<ISourceComplexType> ISourceComplexTypeCollection<ISourceComplexType>.Types
         => [.. Members];
 
-    public bool TryGetType(string schemaName, [NotNullWhen(true)] out SourceObjectType? type)
-        => TryGetMember(schemaName, out type);
-
-    public bool TryGetType(string schemaName, [NotNullWhen(true)] out ISourceComplexType? type)
+    public bool TryGetMember(string schemaName, [NotNullWhen(true)] out ISourceComplexType? type)
     {
-        if (TryGetMember(schemaName, out var member))
+        if (base.TryGetMember(schemaName, out var member))
         {
             type = member;
             return true;

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Collections/SourceUnionTypeCollection.cs

@@ -0,0 +1,6 @@
+namespace HotChocolate.Fusion.Types.Collections;
+
+public class SourceUnionTypeCollection(IEnumerable<SourceUnionType> members)
+    : SourceMemberCollection<SourceUnionType>(members)
+{
+}

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Completion/CompletionTools.cs

@@ -137,6 +137,29 @@ public static SourceInterfaceTypeCollection CreateSourceInterfaceTypeCollection(
         return new SourceInterfaceTypeCollection(temp);
     }
 
+    public static SourceUnionTypeCollection CreateSourceUnionTypeCollection(
+        UnionTypeDefinitionNode typeDef,
+        CompositeSchemaBuilderContext context)
+    {
+        var types = TypeDirectiveParser.Parse(typeDef.Directives);
+        var lookupDirectives = LookupDirectiveParser.Parse(typeDef.Directives);
+        var temp = new SourceUnionType[types.Length];
+
+        for (var i = 0; i < types.Length; i++)
+        {
+            var type = types[i];
+            var lookups = GetLookupBySchema(lookupDirectives, type.SchemaName, typeDef.Name.Value);
+            context.RegisterForCompletionRange(lookups);
+
+            temp[i] = new SourceUnionType(
+                typeDef.Name.Value,
+                type.SchemaName,
+                lookups);
+        }
+
+        return new SourceUnionTypeCollection(temp);
+    }
+
     private static ImmutableArray<Lookup> GetLookupBySchema(
         ImmutableArray<LookupDirective> allLookups,
         string schemaName,

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Completion/CompositeSchemaBuilder.cs

@@ -532,7 +532,8 @@ private static void CompleteUnionType(
     {
         var directives = CompletionTools.CreateDirectiveCollection(typeDef.Directives, context);
         var types = CompletionTools.CreateObjectTypeCollection(typeDef.Types, context);
-        type.Complete(new CompositeUnionTypeCompletionContext(types, directives, FeatureCollection.Empty));
+        var sources = CompletionTools.CreateSourceUnionTypeCollection(typeDef, context);
+        type.Complete(new CompositeUnionTypeCompletionContext(types, directives, sources, FeatureCollection.Empty));
     }
 
     private static void CompleteOutputField(

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Completion/CompositeUnionTypeCompletionContext.cs

@@ -6,11 +6,14 @@ namespace HotChocolate.Fusion.Types.Completion;
 internal readonly ref struct CompositeUnionTypeCompletionContext(
     FusionObjectTypeDefinitionCollection types,
     FusionDirectiveCollection directives,
+    SourceUnionTypeCollection sources,
     IFeatureCollection features)
 {
     public FusionDirectiveCollection Directives { get; } = directives;
 
     public FusionObjectTypeDefinitionCollection Types { get; } = types;
 
+    public SourceUnionTypeCollection Sources { get; } = sources;
+
     public IFeatureCollection Features { get; } = features;
 }

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Contracts/ISourceComplexTypeCollection.cs

@@ -7,7 +7,5 @@ public interface ISourceComplexTypeCollection<TType>
     : ISourceMemberCollection<TType>
     where TType : ISourceComplexType
 {
-    bool TryGetType(string schemaName, [NotNullWhen(true)] out TType? type);
-
     ImmutableArray<TType> Types { get; }
 }

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Contracts/ISourceMemberCollection.cs

@@ -1,8 +1,9 @@
 using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
 
 namespace HotChocolate.Fusion.Types;
 
-public interface ISourceMemberCollection<out TMember>
+public interface ISourceMemberCollection<TMember>
     : IEnumerable<TMember>
     where TMember : ISourceMember
 {
@@ -13,4 +14,6 @@ public interface ISourceMemberCollection<out TMember>
     bool ContainsSchema(string schemaName);
 
     ImmutableArray<string> Schemas { get; }
+
+    bool TryGetMember(string schemaName, [NotNullWhen(true)] out TMember? type);
 }

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/FusionUnionTypeDefinition.cs

@@ -32,6 +32,23 @@ public FusionUnionTypeDefinition(string name, string? description)
 
     public SchemaCoordinate Coordinate => new(Name, ofDirective: false);
 
+    /// <summary>
+    /// Gets the source type definition of this type.
+    /// </summary>
+    /// <value>
+    /// The source type definition of this type.
+    /// </value>
+    public SourceUnionTypeCollection Sources
+    {
+        get;
+        private set
+        {
+            EnsureNotSealed(_completed);
+
+            field = value;
+        }
+    } = null!;
+
     public FusionObjectTypeDefinitionCollection Types
     {
         get;
@@ -73,6 +90,7 @@ internal void Complete(CompositeUnionTypeCompletionContext context)
 
         Directives = context.Directives;
         Types = context.Types;
+        Sources = context.Sources;
         Features = context.Features;
 
         _completed = true;

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Metadata/Lookup.cs

@@ -17,7 +17,7 @@ public sealed class Lookup : INeedsCompletion
     /// </summary>
     /// <param name="schemaName">The name of the source schema.</param>
     /// <param name="declaringTypeName">The name of the type that declares the field.</param>
-    /// <param name="name">The name of the lookup field.</param>
+    /// <param name="fieldName">The name of the lookup field.</param>
     /// <param name="arguments">The arguments that represent field requirements.</param>
     /// <param name="fields">The paths to the field that are required.</param>
     /// <exception cref="ArgumentException">
@@ -30,13 +30,13 @@ public sealed class Lookup : INeedsCompletion
     public Lookup(
         string schemaName,
         string declaringTypeName,
-        string name,
+        string fieldName,
         ImmutableArray<LookupArgument> arguments,
         ImmutableArray<IValueSelectionNode> fields)
     {
         ArgumentException.ThrowIfNullOrEmpty(schemaName);
         ArgumentException.ThrowIfNullOrEmpty(declaringTypeName);
-        ArgumentException.ThrowIfNullOrEmpty(name);
+        ArgumentException.ThrowIfNullOrEmpty(fieldName);
 
         if (arguments.Length == 0)
         {
@@ -50,7 +50,7 @@ public Lookup(
 
         _declaringTypeName = declaringTypeName;
         SchemaName = schemaName;
-        Name = name;
+        FieldName = fieldName;
         Arguments = arguments;
         Fields = fields;
     }
@@ -63,7 +63,12 @@ public Lookup(
     /// <summary>
     /// Gets the name of the lookup field.
     /// </summary>
-    public string Name { get; }
+    public string FieldName { get; }
+
+    /// <summary>
+    /// Get the name of lookup field type.
+    /// </summary>
+    public string FieldType => _declaringTypeName;
 
     /// <summary>
     /// Gets the arguments that represent field requirements.

src/HotChocolate/Fusion-vnext/src/Fusion.Execution.Types/Metadata/SourceUnionType.cs

@@ -0,0 +1,15 @@
+using System.Collections.Immutable;
+
+namespace HotChocolate.Fusion.Types;
+
+public sealed class SourceUnionType(
+    string name,
+    string schemaName,
+    ImmutableArray<Lookup> lookups) : ISourceMember
+{
+    public string Name { get; } = name;
+
+    public string SchemaName { get; } = schemaName;
+
+    public ImmutableArray<Lookup> Lookups { get; } = lookups;
+}

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Planning/OperationDefinitionBuilder.cs

@@ -12,6 +12,7 @@ internal sealed class OperationDefinitionBuilder
     private string? _name;
     private string? _description;
     private Lookup? _lookup;
+    private string? _lookupTypeRefinement;
     private string? _requirementKey;
     private SelectionSetNode? _selectionSet;
 
@@ -40,9 +41,10 @@ public OperationDefinitionBuilder SetDescription(string? description)
         return this;
     }
 
-    public OperationDefinitionBuilder SetLookup(Lookup? lookup, string? requirementKey)
+    public OperationDefinitionBuilder SetLookup(Lookup? lookup, string? lookupTypeRefinement, string? requirementKey)
     {
         _lookup = lookup;
+        _lookupTypeRefinement = lookupTypeRefinement;
         _requirementKey = requirementKey;
         return this;
     }
@@ -76,7 +78,7 @@ public OperationDefinitionBuilder SetSelectionSet(SelectionSetNode selectionSet)
             }
 
             var lookupField = new FieldNode(
-                new NameNode(_lookup.Name),
+                new NameNode(_lookup.FieldName),
                 null,
                 [],
                 arguments,
@@ -87,7 +89,13 @@ public OperationDefinitionBuilder SetSelectionSet(SelectionSetNode selectionSet)
             var indexBuilder = index.ToBuilder();
             indexBuilder.Register(selectionSet);
             index = indexBuilder;
-            selectionPath = selectionPath.AppendField(_lookup.Name);
+
+            if (!string.IsNullOrEmpty(_lookupTypeRefinement))
+            {
+                selectionPath = selectionPath.AppendFragment(_lookupTypeRefinement);
+            }
+
+            selectionPath = selectionPath.AppendField(_lookup.FieldName);
         }
 
         var definition = new OperationDefinitionNode(