Strating to refactor SelectableAssociationTrait into a separate class

src/ORM/Association.php

@@ -1026,6 +1026,15 @@ abstract public function type();
      */
     abstract public function eagerLoader(array $options);
 
+    /**
+     * Returns true if the eager loading process will require a set of the owning table's
+     * binding keys in order to use them as a filter in the finder query.
+     *
+     * @param array $options The options containing the strategy to be used.
+     * @return bool true if a list of keys will be required
+     */
+    abstract function requiresKeys(array $options = []);
+
     /**
      * Handles cascading a delete from an associated model.
      *

src/ORM/Association/BelongsToMany.php

@@ -37,7 +37,6 @@ class BelongsToMany extends Association
 {
 
     use ExternalAssociationTrait {
-        _options as _externalOptions;
         _buildQuery as _buildBaseQuery;
     }
 
@@ -1365,7 +1364,6 @@ protected function _junctionTableName($name = null)
      */
     protected function _options(array $opts)
     {
-        $this->_externalOptions($opts);
         if (!empty($opts['targetForeignKey'])) {
             $this->targetForeignKey($opts['targetForeignKey']);
         }
@@ -1378,5 +1376,8 @@ protected function _options(array $opts)
         if (!empty($opts['saveStrategy'])) {
             $this->saveStrategy($opts['saveStrategy']);
         }
+        if (isset($opts['sort'])) {
+            $this->sort($opts['sort']);
+        }
     }
 }

src/ORM/Association/ExternalAssociationTrait.php

@@ -123,17 +123,4 @@ protected function _buildResultMap($fetchQuery, $options)
 
         return $resultMap;
     }
-
-    /**
-     * Parse extra options passed in the constructor.
-     *
-     * @param array $opts original list of options passed in constructor
-     * @return void
-     */
-    protected function _options(array $opts)
-    {
-        if (isset($opts['sort'])) {
-            $this->sort($opts['sort']);
-        }
-    }
 }

src/ORM/Association/HasMany.php

@@ -35,9 +35,7 @@ class HasMany extends Association
 {
 
     use DependentDeleteTrait;
-    use ExternalAssociationTrait {
-        _options as _externalOptions;
-    }
+    use ExternalAssociationTrait;
 
     /**
      * The type of join to be used when adding the association to a query
@@ -534,9 +532,11 @@ public function type()
      */
     protected function _options(array $opts)
     {
-        $this->_externalOptions($opts);
         if (!empty($opts['saveStrategy'])) {
             $this->saveStrategy($opts['saveStrategy']);
         }
+        if (isset($opts['sort'])) {
+            $this->sort($opts['sort']);
+        }
     }
 }

src/ORM/Association/HasOne.php

@@ -16,6 +16,7 @@
 
 use Cake\Datasource\EntityInterface;
 use Cake\ORM\Association;
+use Cake\ORM\Association\Loader\SelectLoader;
 use Cake\ORM\Table;
 use Cake\Utility\Inflector;
 
@@ -29,7 +30,6 @@ class HasOne extends Association
 {
 
     use DependentDeleteTrait;
-    use SelectableAssociationTrait;
 
     /**
      * Valid strategies for this type of association
@@ -128,41 +128,31 @@ public function saveAssociated(EntityInterface $entity, array $options = [])
         return $entity;
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    protected function _linkField($options)
-    {
-        $links = [];
-        $name = $this->alias();
-
-        foreach ((array)$options['foreignKey'] as $key) {
-            $links[] = sprintf('%s.%s', $name, $key);
-        }
-
-        if (count($links) === 1) {
-            return $links[0];
-        }
-
-        return $links;
+    public function eagerLoader(array $options) {
+        $loader = new SelectLoader([
+            'alias' => $this->alias(),
+            'sourceAlias' => $this->source()->alias(),
+            'targetAlias' => $this->target()->alias(),
+            'foreignKey' => $this->foreignKey(),
+            'bindingKey' => $this->bindingKey(),
+            'strategy' => $this->strategy(),
+            'associationType' => $this->type(),
+            'finder' => [$this, 'find']
+        ]);
+        return $loader->buildLoadingQuery($options);
     }
 
     /**
-     * {@inheritDoc}
+     * Returns true if the eager loading process will require a set of the owning table's
+     * binding keys in order to use them as a filter in the finder query.
+     *
+     * @param array $options The options containing the strategy to be used.
+     * @return bool true if a list of keys will be required
      */
-    protected function _buildResultMap($fetchQuery, $options)
+    public function requiresKeys(array $options = [])
     {
-        $resultMap = [];
-        $key = (array)$options['foreignKey'];
-
-        foreach ($fetchQuery->all() as $result) {
-            $values = [];
-            foreach ($key as $k) {
-                $values[] = $result[$k];
-            }
-            $resultMap[implode(';', $values)] = $result;
-        }
+        $strategy = isset($options['strategy']) ? $options['strategy'] : $this->strategy();
 
-        return $resultMap;
+        return $strategy === $this::STRATEGY_SELECT;
     }
 }