Added headers field in Entry

app/DoctrineMigrations/Version20170511115400.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace Application\Migrations;
+
+use Doctrine\DBAL\Migrations\AbstractMigration;
+use Doctrine\DBAL\Schema\Schema;
+use Symfony\Component\DependencyInjection\ContainerAwareInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Added `headers` field in entry table.
+ */
+class Version20170511115400 extends AbstractMigration implements ContainerAwareInterface
+{
+    /**
+     * @var ContainerInterface
+     */
+    private $container;
+
+    public function setContainer(ContainerInterface $container = null)
+    {
+        $this->container = $container;
+    }
+
+    private function getTable($tableName)
+    {
+        return $this->container->getParameter('database_table_prefix').$tableName;
+    }
+
+    /**
+     * @param Schema $schema
+     */
+    public function up(Schema $schema)
+    {
+        $entryTable = $schema->getTable($this->getTable('entry'));
+
+        $this->skipIf($entryTable->hasColumn('headers'), 'It seems that you already played this migration.');
+
+        $entryTable->addColumn('headers', 'text', [
+            'notnull' => false,
+        ]);
+    }
+
+    /**
+     * @param Schema $schema
+     */
+    public function down(Schema $schema)
+    {
+        $entryTable = $schema->getTable($this->getTable('entry'));
+
+        $this->skipIf(!$entryTable->hasColumn('headers'), 'It seems that you already played this migration.');
+
+        $entryTable->dropColumn('headers');
+    }
+}