Allow literal default values (#80)

Co-authored-by: bertramakers <bertramakers@users.noreply.github.com>
Co-authored-by: Toby Zerner <toby.zerner@gmail.com>

Author: bertramakers

docs/fields.md

@@ -200,13 +200,18 @@ Str::make('email')->writableOnCreate();
 ### Default Values
 
 If you would like to provide a default value to be used when creating a new
-resource if there is no value provided in the request, you can pass a closure to
-the `default` method:
+resource if there is no value provided in the request, you can pass a closure or
+a literal value to the `default` method.
+
+A closure will receive the current request context as an argument when called.
 
 ```php
-use Tobyz\JsonApiServer\Field\DateTime;
+use Tobyz\JsonApiServer\Field;
 
-DateTime::make('joinedAt')->default(fn() => new \DateTime());
+Field\Str::make('name')->default('Anonymous');
+Field\DateTime::make('joinedAt')->default(
+    fn(Context $context) => new \DateTime(),
+);
 ```
 
 ### Required

src/Schema/Concerns/SetsValue.php

@@ -51,8 +51,12 @@ public function required(bool $required = true): static
     /**
      * Set a default value for this field.
      */
-    public function default(?Closure $default): static
+    public function default(mixed $default): static
     {
+        if (!$default instanceof Closure) {
+            $default = fn() => $default;
+        }
+
         $this->default = $default;
 
         return $this;

tests/feature/FieldDefaultTest.php

@@ -17,7 +17,7 @@ public function setUp(): void
         $this->api = new JsonApi();
     }
 
-    public function test_default_value_used_if_field_not_present()
+    public function test_default_closure_value_used_if_field_not_present()
     {
         $this->api->resource(
             new MockResource(
@@ -43,6 +43,32 @@ public function test_default_value_used_if_field_not_present()
         );
     }
 
+    public function test_default_literal_value_used_if_field_not_present()
+    {
+        $this->api->resource(
+            new MockResource(
+                'users',
+                endpoints: [Create::make()],
+                fields: [
+                    Attribute::make('name')
+                        ->writable()
+                        ->default('default'),
+                ],
+            ),
+        );
+
+        $response = $this->api->handle(
+            $this->buildRequest('POST', '/users')->withParsedBody([
+                'data' => ['type' => 'users'],
+            ]),
+        );
+
+        $this->assertJsonApiDocumentSubset(
+            ['data' => ['attributes' => ['name' => 'default']]],
+            $response->getBody(),
+        );
+    }
+
     public function test_default_value_not_used_if_field_present()
     {
         $this->api->resource(