From fc773c5c2229f8915010dc1446af9610205326ac Mon Sep 17 00:00:00 2001
From: Andrew Short <andrewjshort@gmail.com>
Date: Wed, 13 Nov 2013 16:21:18 +1100
Subject: [PATCH] NEW: Pre-populate and disable foreign key field on has many
 lists.

This is a common use case, and by default a form field is added which
has no effect. While this coupling is undesirable, it makes the default
behaviour much more sensible.

See #2662, #2651, #2637 for more information.
---
 forms/gridfield/GridFieldDetailForm.php       | 18 +++++++++++++
 .../gridfield/GridFieldDetailFormTest.php     | 25 +++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/forms/gridfield/GridFieldDetailForm.php b/forms/gridfield/GridFieldDetailForm.php
index 1e0b3e37f..108af996d 100644
--- a/forms/gridfield/GridFieldDetailForm.php
+++ b/forms/gridfield/GridFieldDetailForm.php
@@ -372,8 +372,26 @@ class GridFieldDetailForm_ItemRequest extends RequestHandler {
 				$actions->push(new LiteralField('cancelbutton', $text));
 			}
 		}
+
 		$fields = $this->component->getFields();
 		if(!$fields) $fields = $this->record->getCMSFields();
+
+		// If we are creating a new record in a has-many list, then
+		// pre-populate the record's foreign key. Also disable the form field as
+		// it has no effect.
+		if($list instanceof HasManyList) {
+			$key = $list->getForeignKey();
+			$id = $list->getForeignID();
+
+			if(!$this->record->isInDB()) {
+				$this->record->$key = $id;
+			}
+
+			if($field = $fields->dataFieldByName($key)) {
+				$fields->makeFieldReadonly($field);
+			}
+		}
+
 		$form = new Form(
 			$this,
 			'ItemEditForm',
diff --git a/tests/forms/gridfield/GridFieldDetailFormTest.php b/tests/forms/gridfield/GridFieldDetailFormTest.php
index ee729310d..881b13941 100644
--- a/tests/forms/gridfield/GridFieldDetailFormTest.php
+++ b/tests/forms/gridfield/GridFieldDetailFormTest.php
@@ -220,6 +220,31 @@ class GridFieldDetailFormTest extends FunctionalTest {
 		$form = $request->ItemEditForm();
 		$this->assertNotNull($form->Fields()->fieldByName('Callback'));
 	}
+
+	/**
+	 * Tests that a has-many detail form is pre-populated with the parent ID.
+	 */
+	public function testHasManyFormPrePopulated() {
+		$group = $this->objFromFixture(
+			'GridFieldDetailFormTest_PeopleGroup', 'group'
+		);
+
+		$this->logInWithPermission('ADMIN');
+
+		$response = $this->get('GridFieldDetailFormTest_Controller');
+		$parser = new CSSContentParser($response->getBody());
+		$addLink = $parser->getBySelector('.ss-gridfield .new-link');
+		$addLink = (string) $addLink[0]['href'];
+
+		$response = $this->get($addLink);
+		$parser = new CSSContentParser($response->getBody());
+		$title = $parser->getBySelector('#GroupID span');
+		$id = $parser->getBySelector('#GroupID input');
+
+		$this->assertEquals($group->Name, (string) $title[0]);
+		$this->assertEquals($group->ID, (string) $id[0]['value']);
+	}
+
 }
 
 class GridFieldDetailFormTest_Person extends DataObject implements TestOnly {