Add injectArgs option to @can directive to pass along client defined arguments to the policy check

docs/master/api-reference/directives.md

@@ -476,6 +476,10 @@ directive @can(
   Additional arguments that are passed to `Gate::check`. 
   """
   args: [String!]
+  """
+  Pass input variables as arguments that are passed to `Gate::check`. 
+  """
+  input: Boolean!
 ) on FIELD_DEFINITION
 ```
 
@@ -527,6 +531,15 @@ type Mutation {
 }
 ```
 
+You can pass the input variables as arguments to the policy setting `input` argument
+```graphql
+type Mutation {
+    createPost(input: PostInput): Post
+        @can(ability: "create", input: "true")
+}
+```
+Now you will have access to `PostInput` values in the policy 
+
 Starting from Laravel 5.7, [authorization of guest users](https://laravel.com/docs/authorization#guest-users) is supported.
 Because of this, Lighthouse does **not** validate that the user is authenticated before passing it along to the policy.
 

src/Schema/Directives/CanDirective.php

@@ -21,6 +21,11 @@ class CanDirective extends BaseDirective implements FieldMiddleware, DefinedDire
      */
     protected $gate;
 
+    /**
+     * @var array
+     */
+    protected $args;
+
     /**
      * CanDirective constructor.
      * @param  \Illuminate\Contracts\Auth\Access\Gate  $gate
@@ -63,6 +68,11 @@ public static function definition(): string
   Additional arguments that are passed to `Gate::check`. 
   """
   args: [String!]
+    """
+  Send input data as arguments to the policy. 
+  Set false by default
+  """
+  input: Boolean!
 ) on FIELD_DEFINITION
 SDL;
     }
@@ -81,6 +91,7 @@ public function handleField(FieldValue $fieldValue, Closure $next): FieldValue
         return $next(
             $fieldValue->setResolver(
                 function ($root, array $args, GraphQLContext $context, ResolveInfo $resolveInfo) use ($previousResolver) {
+                    $this->args = $args;
                     if ($find = $this->directiveArgValue('find')) {
                         $modelOrModels = $resolveInfo
                             ->argumentSet
@@ -146,6 +157,9 @@ protected function authorize($user, $model): void
      */
     protected function getAdditionalArguments(): array
     {
-        return (array) $this->directiveArgValue('args');
+        $directiveArgs = (array) $this->directiveArgValue('args');
+        $inputArgs = $this->directiveArgValue('input') === true ? [$this->args] : [];
+
+        return array_merge($directiveArgs, $inputArgs);
     }
 }

tests/Unit/Schema/Directives/CanDirectiveTest.php

@@ -141,7 +141,7 @@ public function testProcessesTheArgsArgument(): void
                 @can(ability: "dependingOnArg", args: [false])
                 @field(resolver: "'.$this->qualifyTestResolver('resolveUser').'")
         }
-        
+
         type User {
             name: String
         }
@@ -156,6 +156,41 @@ public function testProcessesTheArgsArgument(): void
         ')->assertErrorCategory(AuthorizationException::CATEGORY);
     }
 
+    public function testSendInputArgumentToPolicy(): void
+    {
+        $this->be(new User);
+        $this->schema = '
+        type Query {
+            users(key1: String, key2: String, key3: String): [User]!
+                @can(ability:"severalArgs", input: true)
+                @field(resolver: "'.$this->qualifyTestResolver('resolveUser').'")
+        }
+
+        type User {
+            name: String
+        }
+        ';
+
+        $variables = [
+            'key1' => 'foo',
+            'key2' => 'foo2',
+            'key3' => 'foo3',
+        ];
+
+        $this->postGraphQL(
+            [
+                'operationName' => 'Users',
+                'query' => 'query Users($key1: String, $key2: String, $key3: String) {
+                                users(key1: $key1, key2: $key2, key3: $key3) {
+                                    name
+                                }
+                            }
+                            ',
+                'variables' => $variables,
+            ]
+        )->assertOk();
+    }
+
     public function resolveUser(): User
     {
         $user = new User;

tests/Utils/Policies/UserPolicy.php

@@ -32,4 +32,9 @@ public function dependingOnArg($viewer, bool $pass): bool
     {
         return $pass;
     }
+
+    public function severalArgs($user, array $input): bool
+    {
+        return $input['key1'] === 'foo' && $input['key2'] === 'foo2' && $input['key2'] === 'foo3';
+    }
 }