Allow passing enum values via callable (#1040)

Author: ruudk

src/Type/Definition/EnumType.php

@@ -15,6 +15,7 @@
 use GraphQL\Utils\Utils;
 
 use function is_array;
+use function is_callable;
 use function is_iterable;
 use function is_string;
 
@@ -26,10 +27,11 @@
  *   description?: string|null,
  *   astNode?: EnumValueDefinitionNode|null,
  * }
+ * @phpstan-type EnumValues iterable<string, PartialEnumValueConfig>|iterable<string, mixed>|iterable<int, string>
  * @phpstan-type EnumTypeConfig array{
  *   name?: string|null,
  *   description?: string|null,
- *   values: iterable<string, PartialEnumValueConfig>|iterable<string, mixed>|iterable<int, string>,
+ *   values: EnumValues|callable(): EnumValues,
  *   astNode?: EnumTypeDefinitionNode|null,
  *   extensionASTNodes?: array<int, EnumTypeExtensionNode>|null,
  * }
@@ -96,8 +98,13 @@ public function getValues(): array
         if (! isset($this->values)) {
             $this->values = [];
 
+            $values = $this->config['values'];
+            if (is_callable($values)) {
+                $values = $values();
+            }
+
             // We are just assuming the config option is set correctly here, validation happens in assertValid()
-            foreach ($this->config['values'] as $name => $value) {
+            foreach ($values as $name => $value) {
                 if (is_string($name)) {
                     if (is_array($value)) {
                         $value += ['name' => $name, 'value' => $name];
@@ -183,10 +190,10 @@ public function assertValid(): void
 
         $values = $this->config['values'] ?? null;
         // @phpstan-ignore-next-line should not happen if used correctly
-        if (! is_iterable($values)) {
+        if (! is_iterable($values) && ! is_callable($values)) {
             $notIterable = Utils::printSafe($values);
 
-            throw new InvariantViolation("{$this->name} values must be an iterable, got: {$notIterable}");
+            throw new InvariantViolation("{$this->name} values must be an iterable or callable, got: {$notIterable}");
         }
 
         $this->getValues();

tests/Type/DefinitionTest.php

@@ -1684,6 +1684,19 @@ public function testAcceptsAWellDefinedEnumTypeWithInternalValueDefinition(): vo
         self::assertEquals(20, $enumType->getValue('BAR')->value);
     }
 
+    public function testAcceptsACallableAsEnumValues(): void
+    {
+        $enumType = new EnumType([
+            'name'   => 'SomeEnum',
+            'values' => static function (): iterable {
+                yield 'FOO' => ['value' => 10];
+                yield 'BAR' => ['value' => 20];
+            },
+        ]);
+        self::assertEquals(10, $enumType->getValue('FOO')->value);
+        self::assertEquals(20, $enumType->getValue('BAR')->value);
+    }
+
     /**
      * @see it('rejects an Enum type with incorrectly typed values')
      */
@@ -1701,6 +1714,20 @@ public function testRejectsAnEnumTypeWithIncorrectlyTypedValues(): void
         $enumType->assertValid();
     }
 
+    public function testRejectsAnEnumTypeWithIncorrectlyTypedValues2(): void
+    {
+        // @phpstan-ignore-next-line intentionally wrong
+        $enumType = new EnumType([
+            'name'   => 'SomeEnum',
+            'values' => 'FOO',
+        ]);
+
+        $this->expectExceptionObject(new InvariantViolation(
+            'SomeEnum values must be an iterable or callable, got: FOO'
+        ));
+        $enumType->assertValid();
+    }
+
     /**
      * @see it('rejects a Schema which redefines a built-in type')
      */

tests/Type/EnumTypeTest.php

@@ -655,4 +655,40 @@ public function testCallsOverwrittenEnumTypeMethods(): void
             GraphQL::executeQuery($this->schema, $query, null, null, $variables)->toArray(DebugFlag::INCLUDE_DEBUG_MESSAGE)
         );
     }
+
+    public function testLazilyDefineValuesAsCallable(): void
+    {
+        $called = 0;
+
+        $ColorType = new EnumType([
+            'name'   => 'Color',
+            'values' => static function () use (&$called): iterable {
+                $called++;
+                yield 'RED' => ['value' => 0];
+            },
+        ]);
+
+        $QueryType = new ObjectType([
+            'name'   => 'Query',
+            'fields' => [
+                'colorEnum' => [
+                    'type'  => $ColorType,
+                    'args'  => [
+                        'fromEnum' => ['type' => $ColorType],
+                    ],
+                    'resolve' => static function ($rootValue, array $args) {
+                        return $args['fromEnum'];
+                    },
+                ],
+            ],
+        ]);
+
+        $schema = new Schema(['query' => $QueryType]);
+
+        self::assertEquals(
+            ['data' => ['colorEnum' => 'RED']],
+            GraphQL::executeQuery($schema, '{ colorEnum(fromEnum: RED) }')->toArray()
+        );
+        self::assertSame(1, $called);
+    }
 }