Merge pull request #55 from atk4/feature/fix-related-entity-aliases

Fix aliases on related entities.

docs/relations.rst

@@ -7,6 +7,8 @@ Relations
 
 .. php:class:: Model
 
+.. php:method:: ref($link, $defailts = []);
+
 Models can relate one to another. The logic of traversing relations, however, is
 slightly different to the traditional ORM implementation, because in Agile Data
 traversing also imposes :ref:`conditions`
@@ -41,6 +43,10 @@ order will look like this::
         select id from user where is_vip = 1
     ) limit 1
 
+Argument $defaults will be passed to the new model that will be used for
+relation. This will not work if you have specified relation as existing
+model that has a persistence set.
+
 Persistence
 -----------
 
@@ -321,3 +327,64 @@ will ecapsulate sub-queries resulting in a query like this::
             (select user_id from order where id=1 ))
 
 
+Relation Aliases
+================
+
+When related entity relies on the same table it is possible to run into problem when SQL is
+confused about which table to use.
+
+.. code-block:: sql
+
+    select name, (select name from item where item.parent_id = item.id) parent_name from item
+
+To avoid this problem Agile Data will automatically alias tables in sub-queries. Here is how
+it works::
+
+    $item->hasMany('parent_item_id', new Model_Item())
+        ->addField('parent', 'name');
+
+When generating expression for 'parent', the sub-query will use alias ``pi`` consisting of
+first letters in 'parent_item_id'. (except _id). You can actually specify a custom table alias
+if you want::
+
+    $item->hasMany('parent_item_id', [new Model_Item(), 'table_alias'=>'mypi'])
+        ->addField('parent', 'name');
+
+Additionally you can pass table_alias as second argument into ref() or refLink(). This can
+help you in creating a recursive models that relate to itself. Here is example::
+
+    class Model_Item3 extends \atk4\data\Model {
+        public $table='item';
+        function init() {
+            parent::init();
+
+            $m = new Model_Item3();
+
+            $this->addField('name');
+            $this->addField('age');
+            $i2 = $this->join('item2.item_id');
+            $i2->hasOne('parent_item_id', [$m, 'table_alias'=>'parent'])
+                ->addTitle();
+
+            $this->hasMany('Child', [$m, 'their_field'=>'parent_item_id', 'table_alias'=>'child'])
+                ->addField('child_age',['aggregate'=>'sum', 'field'=>'age']);
+        }
+    }
+
+Loading model like that can produce a pretty sophisticated query
+
+.. code-block:: sql
+
+    select
+        `pp`.`id`,`pp`.`name`,`pp`.`age`,`pp_i`.`parent_item_id`,
+        (select `parent`.`name` 
+         from `item` `parent`
+         left join `item2` as `parent_i` on `parent_i`.`item_id` = `parent`.`id` 
+         where `parent`.`id` = `pp_i`.`parent_item_id`
+         ) `parent_item`,
+        (select sum(`child`.`age`) from `item` `child`
+         left join `item2` as `child_i` on `child_i`.`item_id` = `child`.`id` 
+         where `child_i`.`parent_item_id` = `pp`.`id`
+        ) `child_age`,`pp`.`id` `_i` 
+    from `item` `pp`left join `item2` as `pp_i` on `pp_i`.`item_id` = `pp`.`id`
+

src/Field_Many.php

@@ -11,6 +11,10 @@ class Field_Many
     }
     use \atk4\core\InitializerTrait;
 
+    /**
+     * Use this alias for related entity by default.
+     */
+    protected $table_alias;
 
     /**
      * What should we pass into owner->ref() to get
@@ -68,19 +72,33 @@ public function init()
 
     protected function getModel($defaults = [])
     {
+        if (!isset($defaults['table_alias'])) {
+            if (!$this->table_alias) {
+                $this->table_alias = $this->link;
+                $this->table_alias = preg_replace('/_id/', '', $this->table_alias);
+                $this->table_alias = preg_replace('/([a-zA-Z])[a-zA-Z]*[^a-zA-Z]*/', '\1', $this->table_alias);
+            }
+            $defaults['table_alias'] = $this->table_alias;
+        }
+
         if (is_object($this->model) && $this->model instanceof \Closure) {
             $c = $this->model;
 
-            return $c($this->owner, $this, $defaults);
+            $c = $c($this->owner, $this);
+            if (!$c->persistence && $this->owner->persistence) {
+                $c = $this->owner->persistence->add($c, $defaults);
+            }
+
+            return $c;
         }
 
         if (is_object($this->model)) {
-            $m = clone $this->model;
-            if ($defaults) {
-                $m->setDefaults($defaults);
+            if ($this->model->persistence || !$this->owner->persistence) {
+                return clone $this->model;
             }
+            $c = clone $this->model;
 
-            return $m;
+            return $this->owner->persistence->add($c, $defaults);
         }
 
         // last effort - try to add model
@@ -160,9 +178,10 @@ public function addField($n, $defaults = [])
         }
 
         $field = isset($defaults['field']) ? $defaults['field'] : $n;
-        $action = $this->refLink()->action('fx', [$defaults['aggregate'], $field]);
 
-        return $this->owner->addExpression($n, $action);
+        return $this->owner->addExpression($n, function () use ($defaults, $field) {
+            return $this->refLink()->action('fx', [$defaults['aggregate'], $field]);
+        });
     }
 
     public function addFields($fields = [])

src/Field_One.php

@@ -11,6 +11,10 @@ class Field_One
     }
     use \atk4\core\TrackableTrait;
 
+    /**
+     * Use this alias for related entity by default.
+     */
+    protected $table_alias;
 
     /**
      * What should we pass into owner->ref() to get
@@ -72,14 +76,32 @@ public function init()
 
     public function getModel($defaults = [])
     {
+        if (!isset($defaults['table_alias'])) {
+            if (!$this->table_alias) {
+                $this->table_alias = $this->link;
+                $this->table_alias = preg_replace('/_id/', '', $this->table_alias);
+                $this->table_alias = preg_replace('/([a-zA-Z])[a-zA-Z]*[^a-zA-Z]*/', '\1', $this->table_alias);
+            }
+            $defaults['table_alias'] = $this->table_alias;
+        }
         if (is_object($this->model) && $this->model instanceof \Closure) {
             $c = $this->model;
 
-            return $c($this->owner, $this);
+            $c = $c($this->owner, $this);
+            if (!$c->persistence) {
+                $c = $this->owner->persistence->add($c, $defaults);
+            }
+
+            return $c;
         }
 
         if (is_object($this->model)) {
-            return $this->model;
+            $c = clone $this->model;
+            if (!$this->model->persistence && $this->owner->persistence) {
+                $this->owner->persistence->add($c, $defaults);
+            }
+
+            return $c;
         }
 
         // last effort - try to add model

src/Field_SQL.php

@@ -19,13 +19,13 @@ public function getDSQLExpression($expression)
         if (isset($this->owner->persistence_data['use_table_prefixes'])) {
             if ($this->actual) {
                 return $expression->expr('{}.{}', [
-                    $this->join ? $this->join->short_name
+                    $this->join ? (isset($this->join->foreign_alias) ? $this->join->foreign_alias : $this->join->short_name)
                     : ($this->owner->table_alias ?: $this->owner->table),
                     $this->actual,
                 ]);
             } else {
                 return $expression->expr('{}.{}', [
-                    $this->join ? $this->join->short_name
+                    $this->join ? (isset($this->join->foreign_alias) ? $this->join->foreign_alias : $this->join->short_name)
                     : (isset($this->owner->table_alias) ? $this->owner->table_alias : $this->owner->table),
                     $this->short_name,
                 ]);

src/Field_SQL_One.php

@@ -54,7 +54,7 @@ public function refLink()
     public function addTitle()
     {
         $field = str_replace('_id', '', $this->link);
-        $this->owner->addExpression($field, function ($m) use ($their_field) {
+        $this->owner->addExpression($field, function ($m) {
             $mm = $m->refLink($this->link);
 
             return $mm->action('field', [$mm->title_field]);

src/Join_SQL.php

@@ -4,7 +4,7 @@
 
 class Join_SQL extends Join implements \atk4\dsql\Expressionable
 {
-    protected $foreign_alias;
+    public $foreign_alias;
     /**
      * A short symbolic name that will be used as an alias for the joined table.
      */
@@ -65,7 +65,7 @@ public function init()
 
         // Our short name will be unique
         if (!$this->foreign_alias) {
-            $this->foreign_alias = $this->short_name;
+            $this->foreign_alias = (isset($this->owner->table_alias) ? $this->owner->table_alias : '').$this->short_name;
         }
 
         $this->dsql->table($this->foreign_table, $this->foreign_alias);
@@ -114,12 +114,16 @@ public function initSelectQuery($model, $query)
             ),
             (
                 isset($this->owner->table_alias) ?
-                $this->owner->table_alias :
+                ($this->owner->table_alias.'.'.$this->master_field) :
                 ($this->owner->table).'.'.$this->master_field)
         );
 
         if ($this->reverse) {
-            $query->field([$this->short_name => ($this->join ?: ($this->owner->table.'.'.$this->master_field))]);
+            $query->field([$this->short_name => ($this->join ?:
+                (
+                    (isset($this->owner->table_alias) ? $this->owner->table_alias : $this->owner->table)
+                    .'.'.$this->master_field)
+            )]);
         } else {
             $query->field([$this->short_name => $this->foreign_alias.'.'.$this->foreign_field]);
         }

src/Persistence_SQL.php

@@ -507,7 +507,7 @@ public function delete(Model $m, $id)
     {
         $delete = $this->action($m, 'delete');
         $delete->reset('where'); // because it could have join there..
-        $delete->where($m->getElement($m->id_field), $id);
+        $delete->where($m->id_field, $id);
         $m->hook('beforeDeleteQuery', [$delete]);
         try {
             $delete->execute();

tests/RandomTest.php

@@ -17,6 +17,51 @@ public function init()
         $this->addField('ask');
     }
 }
+class Model_Item extends \atk4\data\Model
+{
+    public $table = 'item';
+
+    public function init()
+    {
+        parent::init();
+        $this->addField('name');
+        $this->hasOne('parent_item_id', '\atk4\data\tests\Item')
+            ->addTitle();
+    }
+}
+class Model_Item2 extends \atk4\data\Model
+{
+    public $table = 'item';
+
+    public function init()
+    {
+        parent::init();
+        $this->addField('name');
+        $i2 = $this->join('item2.item_id');
+        $i2->hasOne('parent_item_id', new self())
+            ->addTitle();
+    }
+}
+class Model_Item3 extends \atk4\data\Model
+{
+    public $table = 'item';
+
+    public function init()
+    {
+        parent::init();
+
+        $m = new self();
+
+        $this->addField('name');
+        $this->addField('age');
+        $i2 = $this->join('item2.item_id');
+        $i2->hasOne('parent_item_id', [$m, 'table_alias' => 'parent'])
+            ->addTitle();
+
+        $this->hasMany('Child', [$m, 'their_field' => 'parent_item_id', 'table_alias' => 'child'])
+            ->addField('child_age', ['aggregate' => 'sum', 'field' => 'age']);
+    }
+}
 
 
 
@@ -128,4 +173,76 @@ public function testBasic()
             $m->action('select')->render()
         );
     }
+
+    public function testSameTable()
+    {
+        $db = new Persistence_SQL($this->db->connection);
+        $a = [
+            'item' => [
+                1 => ['id' => 1, 'name' => 'John', 'parent_item_id' => '1'],
+                2 => ['id' => 2, 'name' => 'Sue', 'parent_item_id' => '1'],
+                3 => ['id' => 3, 'name' => 'Smith', 'parent_item_id' => '2'],
+            ], ];
+        $this->setDB($a);
+
+        $m = new Model_Item($db, 'item');
+
+        $this->assertEquals(
+            ['id' => '3', 'name' => 'Smith', 'parent_item_id' => '2', 'parent_item' => 'Sue'],
+            $m->load(3)->get()
+        );
+    }
+
+    public function testSameTable2()
+    {
+        $db = new Persistence_SQL($this->db->connection);
+        $a = [
+            'item' => [
+                1 => ['id' => 1, 'name' => 'John'],
+                2 => ['id' => 2, 'name' => 'Sue'],
+                3 => ['id' => 3, 'name' => 'Smith'],
+            ],
+            'item2' => [
+                1 => ['id' => 1, 'item_id' => 1, 'parent_item_id' => '1'],
+                2 => ['id' => 2, 'item_id' => 2, 'parent_item_id' => '1'],
+                3 => ['id' => 3, 'item_id' => 3, 'parent_item_id' => '2'],
+            ],
+        ];
+        $this->setDB($a);
+
+        $m = new Model_Item2($db, 'item');
+
+        $this->assertEquals(
+            ['id' => '3', 'name' => 'Smith', 'parent_item_id' => '2', 'parent_item' => 'Sue'],
+            $m->load(3)->get()
+        );
+    }
+
+    public function testSameTable3()
+    {
+        $db = new Persistence_SQL($this->db->connection);
+        $a = [
+            'item' => [
+                1 => ['id' => 1, 'name' => 'John', 'age' => 18],
+                2 => ['id' => 2, 'name' => 'Sue', 'age' => 20],
+                3 => ['id' => 3, 'name' => 'Smith', 'age' => 24],
+            ],
+            'item2' => [
+                1 => ['id' => 1, 'item_id' => 1, 'parent_item_id' => '1'],
+                2 => ['id' => 2, 'item_id' => 2, 'parent_item_id' => '1'],
+                3 => ['id' => 3, 'item_id' => 3, 'parent_item_id' => '2'],
+            ],
+        ];
+        $this->setDB($a);
+
+        $m = new Model_Item3($db, 'item');
+
+        $this->assertEquals(
+            ['id' => '2', 'name' => 'Sue', 'parent_item_id' => '1', 'parent_item' => 'John', 'age' => '20', 'child_age' => 24],
+            $m->load(2)->get()
+        );
+
+        $this->assertEquals(1, $m->load(2)->ref('Child', ['table_alias' => 'pp'])->action('count')->getOne());
+        $this->assertEquals('John', $m->load(2)->ref('parent_item_id', ['table_alias' => 'pp'])->get('name'));
+    }
 }