Rails model if statement

I'm new to rails and app development so forgive any mistakes.

I've got a model called Product which has the following (schema):

    t.string   "name"
    t.integer  "cost"
    t.boolean  "in_stock"
    t.datetime "sold_date"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.integer  "quantity"

I want the in_stock to return true if the quantity is greater than 1, otherwise false. I wrote the following code in the product.rb file but it doesn't seem do anything when I enter the product quantities through the console. I'm not sure if I have to link the database columns (in_stock and quantity) to the if statement or not. Or if even this is the right way to go about things. I'd be grateful for any suggestions. Thanks!

class Product < ActiveRecord::Base
belongs_to :company

def in_stock
    if  quantity >= 1 
        in_stock true
    else 
        in_stock false
end