[Fusion] Do not send omitted arguments with default values to subgraph

src/HotChocolate/Fusion/src/Core/Metadata/ResolverDefinition.FetchRewriterContext.cs

@@ -11,12 +11,14 @@ public FetchRewriterContext(
             FragmentSpreadNode? placeholder,
             IReadOnlyDictionary<string, IValueNode> variables,
             SelectionSetNode? selectionSet,
-            string? responseName)
+            string? responseName,
+            IReadOnlyList<string>? unspecifiedArguments)
         {
             Placeholder = placeholder;
             Variables = variables;
             SelectionSet = selectionSet;
             ResponseName = responseName;
+            UnspecifiedArguments = unspecifiedArguments;
         }
 
         public string? ResponseName { get; }
@@ -29,6 +31,11 @@ public FetchRewriterContext(
 
         public IReadOnlyDictionary<string, IValueNode> Variables { get; }
 
+        /// <summary>
+        /// An optional list of arguments that weren't explicitly specified in the original query.
+        /// </summary>
+        public IReadOnlyList<string>? UnspecifiedArguments { get; }
+
         public SelectionSetNode? SelectionSet { get; }
 
         public IReadOnlyList<string> SelectionPath { get; set; } = Array.Empty<string>();

src/HotChocolate/Fusion/src/Core/Metadata/ResolverDefinition.ResolverRewriter.cs

@@ -12,7 +12,21 @@ private class ResolverRewriter : SyntaxRewriter<FetchRewriterContext>
         {
             var result = base.RewriteField(node, context);
 
-            if (result is not null && context.PlaceholderFound)
+            if (result is null)
+            {
+                return null;
+            }
+
+            if (context.UnspecifiedArguments?.Count > 0)
+            {
+                var explicitlyDefinedArguments = result.Arguments
+                    .ExceptBy(context.UnspecifiedArguments, a => a.Name.Value)
+                    .ToList();
+
+                result = result.WithArguments(explicitlyDefinedArguments);
+            }
+
+            if (context.PlaceholderFound)
             {
                 context.PlaceholderFound = false;
 

src/HotChocolate/Fusion/src/Core/Metadata/ResolverDefinition.cs

@@ -53,9 +53,10 @@ public ResolverDefinition(
     public (ISelectionNode selectionNode, IReadOnlyList<string> Path) CreateSelection(
         IReadOnlyDictionary<string, IValueNode> variables,
         SelectionSetNode? selectionSet,
-        string? responseName)
+        string? responseName,
+        IReadOnlyList<string>? unspecifiedArguments)
     {
-        var context = new FetchRewriterContext(Placeholder, variables, selectionSet, responseName);
+        var context = new FetchRewriterContext(Placeholder, variables, selectionSet, responseName, unspecifiedArguments);
         var selection = _rewriter.Rewrite(_field ?? (ISyntaxNode)Select, context);
 
         if (Placeholder is null && selectionSet is not null)

src/HotChocolate/Fusion/src/Core/Planning/RequestFormatters/NodeRequestDocumentFormatter.cs

@@ -24,7 +24,7 @@ internal RequestDocument CreateRequestDocument(
         OperationType operationType = OperationType.Query)
     {
         var rootSelectionSetNode =
-            CreateRooSelectionSetNode(
+            CreateRootSelectionSetNode(
                 context,
                 executionStep,
                 entityTypeName);
@@ -47,7 +47,7 @@ internal RequestDocument CreateRequestDocument(
             path);
     }
 
-    private SelectionSetNode CreateRooSelectionSetNode(
+    private SelectionSetNode CreateRootSelectionSetNode(
         QueryPlanContext context,
         SelectionExecutionStep executionStep,
         string entityTypeName)
@@ -90,7 +90,8 @@ private SelectionSetNode CreateRooSelectionSetNode(
         var (selectionNode, _) = nodeSelection.Resolver.CreateSelection(
             context.VariableValues,
             selectionSetNode,
-            nodeSelection.Selection.ResponseName);
+            nodeSelection.Selection.ResponseName,
+            null);
 
         if (selectionNode is FieldNode fieldNode &&
             !nodeSelection.Selection.ResponseName.EqualsOrdinal(fieldNode.Name.Value))

src/HotChocolate/Fusion/src/Core/Planning/RequestFormatters/RequestDocumentFormatter.cs

@@ -49,11 +49,14 @@ internal RequestDocument CreateRequestDocument(
                 executionStep.Resolver,
                 executionStep.Variables);
 
+            var unspecifiedArguments = GetUnspecifiedArguments(executionStep.ParentSelection);
+
             var (rootResolver, p) =
                 executionStep.Resolver.CreateSelection(
                     context.VariableValues,
                     rootSelectionSetNode,
-                    null);
+                    null,
+                    unspecifiedArguments);
 
             rootSelectionSetNode = new SelectionSetNode(new[] { rootResolver });
             path = p;
@@ -85,19 +88,16 @@ internal RequestDocument CreateRequestDocument(
     }
 
     private SelectionSetNode CreateRootLevelQuery(
-        SelectionPath path, 
+        SelectionPath path,
         SelectionSetNode selectionSet)
     {
         var current = path;
 
         while (current is not null)
         {
             selectionSet = new SelectionSetNode(
-                new[]
-                {
-                    current.Selection.SyntaxNode.WithSelectionSet(selectionSet)
-                });
-
+                new[] { current.Selection.SyntaxNode.WithSelectionSet(selectionSet) });
+
             current = current.Parent;
         }
 
@@ -165,10 +165,13 @@ protected virtual SelectionSetNode CreateRootSelectionSetNode(
                     rootSelection.Resolver,
                     executionStep.Variables);
 
+                var unspecifiedArguments = GetUnspecifiedArguments(rootSelection.Selection);
+
                 var (s, _) = rootSelection.Resolver.CreateSelection(
                     context.VariableValues,
                     selectionSetNode,
-                    rootSelection.Selection.ResponseName);
+                    rootSelection.Selection.ResponseName,
+                    unspecifiedArguments);
                 selectionNode = s;
             }
 
@@ -278,6 +281,7 @@ protected virtual SelectionSetNode CreateSelectionSetNode(
                     selectionNodes.Add(TypeNameField);
                     needsTypeNameField = false;
                 }
+
                 AddInlineFragment(possibleType);
             }
         }
@@ -314,7 +318,7 @@ protected virtual bool CreateSelectionNodes(
         ref var selection = ref selectionSet.GetSelectionsReference();
         ref var end = ref Unsafe.Add(ref selection, selectionSet.Selections.Count);
 
-        while(Unsafe.IsAddressLessThan(ref selection, ref end))
+        while (Unsafe.IsAddressLessThan(ref selection, ref end))
         {
             if (!executionStep.AllSelections.Contains(selection) &&
                 !selection.Field.Name.EqualsOrdinal(IntrospectionFields.TypeName))
@@ -428,6 +432,14 @@ protected void ResolveRequirements(
                 }
 
                 var argumentValue = selection.Arguments[argumentVariable.ArgumentName];
+
+                if (argumentValue.IsDefaultValue)
+                {
+                    // We don't want to register and pass a value to an argument
+                    // that wasn't explicitly specified in the original operation.
+                    continue;
+                }
+
                 context.VariableValues.Add(variable.Name, argumentValue.ValueLiteral!);
                 TryForwardVariable(
                     context,
@@ -469,9 +481,9 @@ protected void ResolveRequirements(
 
         foreach (var requirement in resolver.Requires)
         {
-            if (!context.VariableValues.ContainsKey(requirement))
+            if (!context.VariableValues.ContainsKey(requirement) &&
+                variableStateLookup.TryGetValue(requirement, out var stateKey))
             {
-                var stateKey = variableStateLookup[requirement];
                 context.VariableValues.Add(requirement, new VariableNode(stateKey));
             }
         }
@@ -529,6 +541,22 @@ protected void TryForwardVariable(
         }
     }
 
+    private static IReadOnlyList<string>? GetUnspecifiedArguments(ISelection selection)
+    {
+        List<string>? unspecifiedArguments = null;
+
+        foreach (var argument in selection.Arguments)
+        {
+            if (argument.IsDefaultValue)
+            {
+                unspecifiedArguments ??= new List<string>();
+                unspecifiedArguments.Add(argument.Name);
+            }
+        }
+
+        return unspecifiedArguments;
+    }
+
     private sealed class VariableVisitor : SyntaxWalker<VariableVisitorContext>
     {
         protected override ISyntaxVisitorAction Enter(