title: update method in adonisjs controller
body: <p>How to update data in the database without creating a new one?</p>
  
  <pre><code>async update ({ params, request, response }) {
      const product = await Product.find(params.id)
  
      product.name = request.input('name')
      product.descr = request.input('descr')
      product.qtd = request.input('qtd')
      product.sub_descr = request.input('sub_descr')
      product.price = request.input('price')
  
      product.save()
  
      return response.redirect('/')
    }
  </code></pre>
  
  <p>This code is creating a new instance, the <code>product.update()</code> method returns me an error</p>