ENHANCEMENT GridField passes in context for canCreate

src/Forms/GridField/GridFieldAddNewButton.php

@@ -3,6 +3,8 @@
 namespace SilverStripe\Forms\GridField;
 
 use SilverStripe\Control\Controller;
+use SilverStripe\ORM\DataObject;
+use SilverStripe\ORM\RelationList;
 use SilverStripe\View\ArrayData;
 use SilverStripe\View\SSViewer;
 
@@ -35,9 +37,16 @@ class GridFieldAddNewButton implements GridField_HTMLProvider
     public function getHTMLFragments($gridField)
     {
         $singleton = singleton($gridField->getModelClass());
+        $context = [];
+        if ($gridField->getList() instanceof RelationList) {
+            $record = $gridField->getForm()->getRecord();
+            if ($record && $record instanceof DataObject) {
+                $context['Parent'] = $record;
+            }
+        }
 
-        if (!$singleton->canCreate()) {
-            return array();
+        if (!$singleton->canCreate(null, $context)) {
+            return [];
         }
 
         if (!$this->buttonName) {
@@ -46,14 +55,14 @@ class GridFieldAddNewButton implements GridField_HTMLProvider
             $this->buttonName = _t('SilverStripe\\Forms\\GridField\\GridField.Add', 'Add {name}', array('name' => $objectName));
         }
 
-        $data = new ArrayData(array(
+        $data = new ArrayData([
             'NewLink' => Controller::join_links($gridField->Link('item'), 'new'),
             'ButtonName' => $this->buttonName,
-        ));
+        ]);
 
         $templates = SSViewer::get_templates_by_class($this, '', __CLASS__);
-        return array(
+        return [
             $this->targetFragment => $data->renderWith($templates),
-        );
+        ];
     }
 }

src/ORM/HasManyList.php

@@ -80,11 +80,11 @@ class HasManyList extends RelationList
 
         // Validate foreignID
         if (!$foreignID) {
-            user_error("ManyManyList::add() can't be called until a foreign ID is set", E_USER_WARNING);
+            user_error("HasManyList::add() can't be called until a foreign ID is set", E_USER_WARNING);
             return;
         }
         if (is_array($foreignID)) {
-            user_error("ManyManyList::add() can't be called on a list linked to mulitple foreign IDs", E_USER_WARNING);
+            user_error("HasManyList::add() can't be called on a list linked to mulitple foreign IDs", E_USER_WARNING);
             return;
         }
 

tests/php/Forms/GridField/GridFieldAddNewButtonTest.php

@@ -0,0 +1,124 @@
+<?php
+
+namespace SilverStripe\Forms\Tests\GridField;
+
+use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Forms\FieldList;
+use SilverStripe\Forms\Form;
+use SilverStripe\Forms\GridField\GridField;
+use SilverStripe\Forms\GridField\GridFieldAddNewButton;
+use SilverStripe\Forms\GridField\GridFieldConfig;
+use SilverStripe\Forms\Tests\GridField\GridFieldDetailFormTest\Person;
+use SilverStripe\Forms\Tests\GridField\GridFieldDetailFormTest\PeopleGroup;
+use SilverStripe\Forms\Tests\GridField\GridFieldDetailFormTest\Category;
+use SilverStripe\Forms\Tests\GridField\GridFieldDetailFormTest\TestController;
+use SilverStripe\ORM\SS_List;
+
+class GridFieldAddNewButtonTest extends SapphireTest
+{
+    protected static $fixture_file = 'GridFieldDetailFormTest.yml';
+
+    protected static $extra_dataobjects = [
+        Person::class,
+        PeopleGroup::class,
+        Category::class,
+    ];
+
+    public function setUp()
+    {
+        parent::setUp();
+        Injector::nest();
+    }
+
+    public function tearDown()
+    {
+        parent::tearDown();
+        Injector::unnest();
+    }
+
+    public function testButtonPassesParentContextToSingletonWhenRelationListIsUsed()
+    {
+        $group = $this->objFromFixture(PeopleGroup::class, 'group');
+        $list = $group->People();
+        $this->mockSingleton(Person::class)
+            ->expects($this->once())
+            ->method('canCreate')
+            ->with(
+                $this->anything(),
+                $this->callback(function ($arg) use ($group) {
+                    return isset($arg['Parent']) && $arg['Parent']->ID == $group->ID;
+                })
+            );
+
+        $this->mockButtonFragments($list, $group);
+    }
+
+    public function testButtonPassesNoParentContextToSingletonWhenRelationListIsNotUsed()
+    {
+        $group = $this->objFromFixture(PeopleGroup::class, 'group');
+        $this->mockSingleton(Person::class)
+            ->expects($this->once())
+            ->method('canCreate')
+            ->with(
+                $this->anything(),
+                $this->callback(function ($arg) {
+                    return !isset($arg['Parent']);
+                })
+            );
+
+        $this->mockButtonFragments(Person::get(), $group);
+    }
+
+    public function testButtonPassesNoParentContextToSingletonWhenNoParentRecordExists()
+    {
+        $group = $this->objFromFixture(PeopleGroup::class, 'group');
+        $list = $group->People();
+
+        $this->mockSingleton(Person::class)
+            ->expects($this->once())
+            ->method('canCreate')
+            ->with(
+                $this->anything(),
+                $this->callback(function ($arg) {
+                    return !isset($arg['Parent']);
+                })
+            );
+
+        $this->mockButtonFragments($list, null);
+    }
+
+    protected function mockButtonFragments(SS_List $list, $parent = null)
+    {
+        $form = Form::create(
+            new TestController(),
+            'test',
+            FieldList::create(
+                $fakeGrid = GridField::create(
+                    'dummy',
+                    'dummy',
+                    $list,
+                    new GridFieldConfig(
+                        $button = new GridFieldAddNewButton()
+                    )
+                )
+            ),
+            FieldList::create()
+        );
+        if ($parent) {
+            $form->loadDataFrom($parent);
+        }
+
+        $button->getHTMLFragments($fakeGrid);
+    }
+
+    protected function mockSingleton($class)
+    {
+        $mock = $this->getMockBuilder($class)
+            ->setMethods(['canCreate'])
+            ->getMock();
+        Injector::inst()->registerService($mock, $class);
+
+        return $mock;
+    }
+}