atk4\data\tests\ReferenceSQLTest::testRelatedExpression PHP Method

    public function testRelatedExpression()
    {
        $vat = 0.23;
        $a = ['invoice' => [1 => ['id' => 1, 'ref_no' => 'INV203'], 2 => ['id' => 2, 'ref_no' => 'INV204'], 3 => ['id' => 3, 'ref_no' => 'INV205']], 'invoice_line' => [['total_net' => $n = 10, 'total_vat' => $n * $vat, 'total_gross' => $n * ($vat + 1), 'invoice_id' => 1], ['total_net' => $n = 30, 'total_vat' => $n * $vat, 'total_gross' => $n * ($vat + 1), 'invoice_id' => 1], ['total_net' => $n = 100, 'total_vat' => $n * $vat, 'total_gross' => $n * ($vat + 1), 'invoice_id' => 2], ['total_net' => $n = 25, 'total_vat' => $n * $vat, 'total_gross' => $n * ($vat + 1), 'invoice_id' => 3], ['total_net' => $n = 25, 'total_vat' => $n * $vat, 'total_gross' => $n * ($vat + 1), 'invoice_id' => 3]]];
        $this->setDB($a);
        $db = new Persistence_SQL($this->db->connection);
        $i = (new Model($db, 'invoice'))->addFields(['ref_no']);
        $l = (new Model($db, 'invoice_line'))->addFields(['invoice_id', 'total_net', 'total_vat', 'total_gross']);
        $i->hasMany('line', $l);
        $i->addExpression('total_net', $i->refLink('line')->action('fx', ['sum', 'total_net']));
        $this->assertEquals('select `invoice`.`id`,`invoice`.`ref_no`,(select sum(`total_net`) from `invoice_line` where `invoice_id` = `invoice`.`id`) `total_net` from `invoice`', $i->action('select')->render());
    }