Add form attribute to hidden inputs when present.

If inputs are placed outside of the form elements the form attribute
needs to be set on the hidden inputs. Without this attribute the empty
state does not submit correctly.

Fixes #3053

lib/Cake/Test/Case/View/Helper/FormHelperTest.php

@@ -3614,18 +3614,22 @@ class FormHelperTest extends CakeTestCase {
 		);
 		$this->assertTags($result, $expected);
 
-		$result = $this->Form->radio('Employee.gender', array('male' => 'Male', 'female' => 'Female'));
+		$result = $this->Form->radio(
+			'Employee.gender',
+			array('male' => 'Male', 'female' => 'Female'),
+			array('form' => 'my-form')
+		);
 		$expected = array(
 			'fieldset' => array(),
 			'legend' => array(),
 			'Gender',
 			'/legend',
-			'input' => array('type' => 'hidden', 'name' => 'data[Employee][gender]', 'value' => '', 'id' => 'EmployeeGender_'),
-			array('input' => array('type' => 'radio', 'name' => 'data[Employee][gender]', 'value' => 'male', 'id' => 'EmployeeGenderMale')),
+			'input' => array('type' => 'hidden', 'name' => 'data[Employee][gender]', 'value' => '', 'id' => 'EmployeeGender_', 'form' => 'my-form'),
+			array('input' => array('type' => 'radio', 'name' => 'data[Employee][gender]', 'value' => 'male', 'id' => 'EmployeeGenderMale', 'form' => 'my-form')),
 			array('label' => array('for' => 'EmployeeGenderMale')),
 			'Male',
 			'/label',
-			array('input' => array('type' => 'radio', 'name' => 'data[Employee][gender]', 'value' => 'female', 'id' => 'EmployeeGenderFemale')),
+			array('input' => array('type' => 'radio', 'name' => 'data[Employee][gender]', 'value' => 'female', 'id' => 'EmployeeGenderFemale', 'form' => 'my-form')),
 			array('label' => array('for' => 'EmployeeGenderFemale')),
 			'Female',
 			'/label',
@@ -4650,15 +4654,18 @@ class FormHelperTest extends CakeTestCase {
 		$this->assertTags($result, $expected);
 
 		$result = $this->Form->select(
-			'Model.multi_field', $options, array('multiple' => 'multiple')
+			'Model.multi_field', $options, array('form' => 'my-form', 'multiple' => 'multiple')
 		);
 		$expected = array(
 			'input' => array(
-				'type' => 'hidden', 'name' => 'data[Model][multi_field]', 'value' => '', 'id' => 'ModelMultiField_'
+				'type' => 'hidden', 'name' => 'data[Model][multi_field]', 'value' => '', 'id' => 'ModelMultiField_',
+				'form' => 'my-form',
 			),
 			'select' => array(
 				'name' => 'data[Model][multi_field][]',
-				'id' => 'ModelMultiField', 'multiple' => 'multiple'
+				'id' => 'ModelMultiField',
+				'multiple' => 'multiple',
+				'form' => 'my-form',
 			),
 			array('option' => array('value' => '0')),
 			'first',
@@ -5674,10 +5681,14 @@ class FormHelperTest extends CakeTestCase {
 		);
 		$this->assertTags($result, $expected);
 
-		$result = $this->Form->checkbox('Model.field', array('id' => 'theID', 'value' => 'myvalue'));
+		$result = $this->Form->checkbox('Model.field', array(
+			'id' => 'theID',
+			'value' => 'myvalue',
+			'form' => 'my-form',
+		));
 		$expected = array(
-			'input' => array('type' => 'hidden', 'name' => 'data[Model][field]', 'value' => '0', 'id' => 'theID_'),
-			array('input' => array('type' => 'checkbox', 'name' => 'data[Model][field]', 'value' => 'myvalue', 'id' => 'theID'))
+			'input' => array('type' => 'hidden', 'name' => 'data[Model][field]', 'value' => '0', 'id' => 'theID_', 'form' => 'my-form'),
+			array('input' => array('type' => 'checkbox', 'name' => 'data[Model][field]', 'value' => 'myvalue', 'id' => 'theID', 'form' => 'my-form'))
 		);
 		$this->assertTags($result, $expected);
 

lib/Cake/View/Helper/FormHelper.php

@@ -1418,7 +1418,8 @@ class FormHelper extends AppHelper {
 				'id' => $options['id'] . '_',
 				'name' => $options['name'],
 				'value' => ($options['hiddenField'] !== true ? $options['hiddenField'] : '0'),
-				'secure' => false
+				'form' => isset($options['form']) ? $options['form'] : null,
+				'secure' => false,
 			);
 			if (isset($options['disabled']) && $options['disabled']) {
 				$hiddenOptions['disabled'] = 'disabled';
@@ -1544,7 +1545,10 @@ class FormHelper extends AppHelper {
 		if ($hiddenField) {
 			if (!isset($value) || $value === '') {
 				$hidden = $this->hidden($fieldName, array(
-					'id' => $attributes['id'] . '_', 'value' => '', 'name' => $attributes['name']
+					'form' => isset($attributes['form']) ? $attributes['form'] : null,
+					'id' => $attributes['id'] . '_',
+					'value' => '',
+					'name' => $attributes['name']
 				));
 			}
 		}
@@ -2008,6 +2012,7 @@ class FormHelper extends AppHelper {
 					'value' => '',
 					'id' => $attributes['id'] . ($style ? '' : '_'),
 					'secure' => false,
+					'form' => isset($attributes['form']) ? $attributes['form'] : null,
 					'name' => $attributes['name']
 				);
 				$select[] = $this->hidden(null, $hiddenAttributes);