Move custom libs to the source tree

libs/SimpleValidator/Validators/Exists.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace SimpleValidator\Validators;
+
+use PDO;
+
+class Exists extends Base
+{
+    private $pdo;
+    private $key;
+    private $table;
+
+    public function __construct($field, $error_message, PDO $pdo, $table, $key = '')
+    {
+        parent::__construct($field, $error_message);
+
+        $this->pdo = $pdo;
+        $this->table = $table;
+        $this->key = $key;
+    }
+
+
+    public function execute(array $data)
+    {
+        if (! $this->isFieldNotEmpty($data)) {
+            return true;
+        }
+
+        if ($this->key === '') {
+            $this->key = $this->field;
+        }
+
+        $rq = $this->pdo->prepare('SELECT 1 FROM '.$this->table.' WHERE '.$this->key.'=?');
+        $rq->execute(array($data[$this->field]));
+
+        return $rq->fetchColumn() == 1;
+    }
+}