Final changes to make after find logic work on joinable associations,

adding test to TranslateBehavior to show how this is possible

src/Collection/CollectionTrait.php

@@ -22,6 +22,7 @@
 use Cake\Collection\Iterator\MapReduce;
 use Cake\Collection\Iterator\ReplaceIterator;
 use Cake\Collection\Iterator\SortIterator;
+use Cake\Collection\Iterator\SyncIterator;
 use LimitIterator;
 
 /**
@@ -750,6 +751,28 @@ public function nest($idPath, $parentPath) {
 		return new Collection($collection);
 	}
 
+	public function insert($path, $values) {
+		$iterator = new SyncIterator($this, new Collection($values));
+		$collection = new Collection($iterator);
+		$path = explode('.', $path);
+		$target = array_pop($path);
+
+		return $collection->map(function($values) use ($path, $target) {
+			list($row, $insert) = $values;
+			$pointer =& $row;
+
+			foreach ($path as $step) {
+				if (!isset($pointer[$step])) {
+					return $row;
+				}
+				$pointer =& $pointer[$step];
+			}
+
+			$pointer[$target] = $insert;
+			return $row;
+		});
+	}
+
 /**
  * Returns an array representation of the results
  *

src/Collection/Iterator/SyncIterator.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         CakePHP(tm) v 3.0.0
+ * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
+ */
+namespace Cake\Collection\Iterator;
+
+use Iterator;
+use MultipleIterator;
+
+class SyncIterator extends MultipleIterator {
+
+	public function __construct(Iterator $left, Iterator $right) {
+		$flags = static::MIT_NEED_ANY|static::MIT_KEYS_NUMERIC;
+		parent::__construct($flags);
+		$this->attachIterator($left);
+		$this->attachIterator($right);
+	}
+
+	public function key() {
+		$key = parent::key();
+		return $key[0];
+	}
+
+}

src/ORM/Association.php

@@ -491,6 +491,30 @@ protected function _copyAttributes($query, $surrogate, $options) {
 		if (!empty($options['fields'])) {
 			$query->select($query->aliasFields($options['fields'], $target->alias()));
 		}
+
+		foreach ($surrogate->formatResults() as $callable) {
+			$query->formatResults(function($results) use ($callable) {
+				$property = $this->property();
+				$extracted = $callable($results->extract($property))->compile();
+				return $results->insert($property, $extracted);
+			});
+		}
+
+		$this->_bindNewAssociations($query, $surrogate, $options);
+	}
+
+	protected function _bindNewAssociations($query, $surrogate, $options) {
+		$contain = $surrogate->contain();
+		$target = $this->_targetTable;
+		if ($contain) {
+			$loader = $surrogate->eagerLoader();
+			$loader->attachAssociations($query, $target, $options['includeFields']);
+			$newBinds = [];
+			foreach ($contain as $alias => $value) {
+				$newBinds[$options['path'] . '.' . $alias] = $value;
+			}
+			$query->contain($newBinds);
+		}
 	}
 
 /**

src/ORM/EagerLoader.php

@@ -251,7 +251,10 @@ public function attachAssociations(Query $query, Table $repository, $includeFiel
 		}
 
 		foreach ($this->attachableAssociations($repository) as $options) {
-			$config = $options['config'] + ['includeFields' => $includeFields];
+			$config = $options['config'] + [
+				'path' => $options['path'],
+				'includeFields' => $includeFields
+			];
 			$options['instance']->attachTo($query, $config);
 		}
 	}

tests/Fixture/TranslateFixture.php

@@ -75,5 +75,6 @@ class TranslateFixture extends TestFixture {
 		array('locale' => 'eng', 'model' => 'Comments', 'foreign_key' => 3, 'field' => 'comment', 'content' => 'Comment #3'),
 		array('locale' => 'eng', 'model' => 'Comments', 'foreign_key' => 4, 'field' => 'comment', 'content' => 'Comment #4'),
 		array('locale' => 'spa', 'model' => 'Comments', 'foreign_key' => 4, 'field' => 'comment', 'content' => 'Comentario #4'),
+		array('locale' => 'eng', 'model' => 'Authors', 'foreign_key' => 1, 'field' => 'name', 'content' => 'May-rianoh')
 	);
 }

tests/TestCase/Model/Behavior/TranslateBehaviorTest.php

@@ -410,4 +410,50 @@ public function testTranslationsHasManyWithOverride() {
 		$this->assertEquals('Obsah #1', $results->first()->body);
 	}
 
+/**
+ * Tests that it is possible to translate belongsTo associations
+ *
+ * @return void
+ */
+	public function testFindSingleLocaleBelongsto() {
+		$table = TableRegistry::get('Articles');
+		$table->addBehavior('Translate', ['fields' => ['title', 'body']]);
+		$authors = $table->belongsTo('Authors')->target();
+		$authors->addBehavior('Translate', ['fields' => ['name']]);
+
+		$table->locale('eng');
+		$authors->locale('eng');
+
+		$results = $table->find()
+			->select(['title', 'body'])
+			->contain(['Authors' => function($q) {
+				return $q->select(['id', 'name']);
+			}]);
+
+		$expected = [
+			[
+				'title' => 'Title #1',
+				'body' => 'Content #1',
+				'author' => ['id' => 1, 'name' => 'May-rianoh', '_locale' => 'eng'],
+				'_locale' => 'eng'
+			],
+			[
+				'title' => 'Title #2',
+				'body' => 'Content #2',
+				'author' => ['id' => 3, 'name' => 'larry', '_locale' => 'eng'],
+				'_locale' => 'eng'
+			],
+			[
+				'title' => 'Title #3',
+				'body' => 'Content #3',
+				'author' => ['id' => 1, 'name' => 'May-rianoh', '_locale' => 'eng'],
+				'_locale' => 'eng'
+			]
+		];
+		$results = array_map(function($r) {
+			return $r->toArray();
+		}, $results->toArray());
+		$this->assertEquals($expected, $results);
+	}
+
 }