Allow default model class resolution for union types

CHANGELOG.md

@@ -9,6 +9,12 @@ You can find and compare releases at the [GitHub release page](https://github.co
 
 ## Unreleased
 
+## v6.10.0
+
+### Added
+
+- Allow default model class resolution for `union` types
+
 ## v6.9.2
 
 ### Fixed

src/Schema/AST/ASTHelper.php

@@ -355,7 +355,10 @@ public static function modelName(Node $definitionNode): ?string
             $definitionNode = static::underlyingType($definitionNode);
         }
 
-        if ($definitionNode instanceof ObjectTypeDefinitionNode || $definitionNode instanceof InterfaceTypeDefinitionNode) {
+        if ($definitionNode instanceof ObjectTypeDefinitionNode
+            || $definitionNode instanceof InterfaceTypeDefinitionNode
+            || $definitionNode instanceof UnionTypeDefinitionNode
+        ) {
             return ModelDirective::modelClass($definitionNode)
                 ?? $definitionNode->name->value;
         }

src/Schema/Directives/BaseDirective.php

@@ -146,11 +146,8 @@ protected function directiveArgValue(string $name, mixed $default = null): mixed
      */
     protected function getModelClass(string $argumentName = 'model'): string
     {
-        $model = $this->directiveArgValue($argumentName, ASTHelper::modelName($this->definitionNode));
-
-        if (! $model) {
-            throw new DefinitionException("Could not determine a model name for the '@{$this->name()}' directive on '{$this->nodeName()}.");
-        }
+        $model = $this->directiveArgValue($argumentName, ASTHelper::modelName($this->definitionNode))
+            ?? throw new DefinitionException("Could not determine a model name for the '@{$this->name()}' directive on '{$this->nodeName()}'.");
 
         return $this->namespaceModelClass($model);
     }

tests/Unit/Schema/Directives/BaseDirectiveTest.php

@@ -39,7 +39,7 @@ public function testGetsModelClassFromDirective(): void
         );
     }
 
-    public function testDefaultsToFieldTypeForTheModelClass(): void
+    public function testDefaultsToFieldTypeForTheModelClassIfObject(): void
     {
         $this->schema .= /** @lang GraphQL */ '
         type User {
@@ -55,6 +55,56 @@ public function testDefaultsToFieldTypeForTheModelClass(): void
         );
     }
 
+    public function testDefaultsToFieldTypeForTheModelClassIfInterface(): void
+    {
+        $this->schema .= /** @lang GraphQL */ '
+        interface User {
+            id: ID
+        }
+        ';
+
+        $directive = $this->constructFieldDirective('foo: User @dummy');
+
+        $this->assertSame(
+            User::class,
+            $directive->getModelClass(),
+        );
+    }
+
+    public function testDefaultsToFieldTypeForTheModelClassIfUnion(): void
+    {
+        $this->schema .= /** @lang GraphQL */ '
+        union User = Admin | Member
+
+        type Admin {
+            id: ID
+        }
+
+        type Member {
+            id: ID
+        }
+        ';
+
+        $directive = $this->constructFieldDirective('foo: User @dummy');
+
+        $this->assertSame(
+            User::class,
+            $directive->getModelClass(),
+        );
+    }
+
+    public function testDoesntDefaultToFieldTypeForTheModelClassIfScalar(): void
+    {
+        $this->schema .= /** @lang GraphQL */ '
+        scalar User
+        ';
+
+        $directive = $this->constructFieldDirective('foo: User @dummy');
+
+        $this->expectException(DefinitionException::class);
+        $directive->getModelClass();
+    }
+
     public function testThrowsIfTheClassIsNotInTheSchema(): void
     {
         $directive = $this->constructFieldDirective('foo: UnknownType @dummy');