Add default name mappers

config/data.php

@@ -1,6 +1,7 @@
 <?php
 
 use Illuminate\Support\Enumerable;
+use Spatie\LaravelData\Mappers\NameMapper;
 
 return [
     /**
@@ -128,6 +129,15 @@
      */
     'validation_strategy' => \Spatie\LaravelData\Support\Creation\ValidationStrategy::OnlyRequests->value,
 
+    /**
+     * The default name mapping strategy for data objects' keys.
+     * This has to be a class implementing the `Spatie\LaravelData\Mappers\NameMapper` interface.
+     */
+    'naming_strategy' => [
+        'input' => null,
+        'output' => null,
+    ],
+
     /**
      * When using an invalid include, exclude, only or except partial, the package will
      * throw an exception. You can disable this behaviour by setting this option to true.

src/Resolvers/NameMappersResolver.php

@@ -34,7 +34,8 @@ protected function resolveInputNameMapper(
     ): ?NameMapper {
         /** @var \Spatie\LaravelData\Attributes\MapInputName|\Spatie\LaravelData\Attributes\MapName|null $mapper */
         $mapper = $attributes->first(fn (object $attribute) => $attribute instanceof MapInputName)
-            ?? $attributes->first(fn (object $attribute) => $attribute instanceof MapName);
+            ?? $attributes->first(fn (object $attribute) => $attribute instanceof MapName)
+            ?? $this->resolveDefaultNameMapper(input: true);
 
         if ($mapper) {
             return $this->resolveMapper($mapper->input);
@@ -48,7 +49,8 @@ protected function resolveOutputNameMapper(
     ): ?NameMapper {
         /** @var \Spatie\LaravelData\Attributes\MapOutputName|\Spatie\LaravelData\Attributes\MapName|null $mapper */
         $mapper = $attributes->first(fn (object $attribute) => $attribute instanceof MapOutputName)
-            ?? $attributes->first(fn (object $attribute) => $attribute instanceof MapName);
+            ?? $attributes->first(fn (object $attribute) => $attribute instanceof MapName)
+            ?? $this->resolveDefaultNameMapper(input: false);
 
         if ($mapper) {
             return $this->resolveMapper($mapper->output);
@@ -86,4 +88,18 @@ protected function resolveMapperClass(int|string|NameMapper $value): NameMapper
 
         return new ProvidedNameMapper($value);
     }
+
+    private function resolveDefaultNameMapper(bool $input): null|MapInputName|MapOutputName
+    {
+        $nameMapper = config('data.naming_strategy.'.($input ? 'input' : 'output'));
+
+        if ($nameMapper === null) {
+            return null;
+        }
+
+        return match ($input) {
+            true => new MapInputName($nameMapper),
+            false => new MapOutputName($nameMapper),
+        };
+    }
 }

tests/Resolvers/NameMappersResolverTest.php

@@ -5,6 +5,7 @@
 use Spatie\LaravelData\Attributes\MapName;
 use Spatie\LaravelData\Attributes\MapOutputName;
 use Spatie\LaravelData\Mappers\CamelCaseMapper;
+use Spatie\LaravelData\Mappers\StudlyCaseMapper;
 use Spatie\LaravelData\Mappers\ProvidedNameMapper;
 use Spatie\LaravelData\Mappers\SnakeCaseMapper;
 use Spatie\LaravelData\Resolvers\NameMappersResolver;
@@ -102,6 +103,20 @@ function getAttributes(object $class): Collection
     ]);
 });
 
+it('can have default mappers', function () {
+    config()->set('data.naming_strategy.input', CamelCaseMapper::class);
+    config()->set('data.naming_strategy.output', SnakeCaseMapper::class);
+
+    $attributes = getAttributes(new class () {
+        public $property;
+    });
+
+    expect($this->resolver->execute($attributes))->toMatchArray([
+        'inputNameMapper' => new CamelCaseMapper(),
+        'outputNameMapper' => new SnakeCaseMapper(),
+    ]);
+});
+
 it('can ignore certain mapper types', function () {
     $attributes = getAttributes(new class () {
         #[MapInputName('input'), MapOutputName(CamelCaseMapper::class)]