Dynamically add columns in an existing table on the fly in cakephp 3

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1

I want to add column in my existing table in cakephp 3.

My ContactsTable.php file code is…

<?php

namespace App\Model\Table;

use Cake\ORM\Table;
use Migrations\AbstractMigration;

class ContactsTable extends Table
{
    public function initialize(array $config)
    {
        $this->addBehavior('Timestamp');            

        $table = $this->table('contacts');
        $table->addColumn('price', 'decimal')->update();

    }
}

I have tried as cakephp 3 documentation but I got error…

Call to a member function addColumn() on a non-object

How do I add columns on-the-fly via the controller?

This question has an answer. at http://stackoverflow.com/questions/37362123/dynamically-add-columns-in-an-existing-table-on-the-fly-in-cakephp-3 but the cache is not getting refreshed on debug false.