I’m a minimalist, so I’m usually looking for creative ways to get rid of items rather than keep track of them. With that said, for my Sinatra Portfolio Project, I created a CRUD app that keeps track of auction items. I started out by reviewing the MVC framework and building Google sheets to organize my ideas around routes and object relationships.
Validations keep data you don’t want out of the database. So, if you don’t want people signing up for your app without a username, you could use an ActiveRecord validation and include it in the pertinent class:
class User < ActiveRecord::Base validates :username, :presence => true end
However, you might need to validate data in ways that are not as common as something like validating the presence of a username. In that case, you would need to create a custom validation. For example, Bidify allows users to list auction items, as well as bid on other people’s items. To ensure users can’t bid on their own item, I created a custom validation. I added
validate :no_self_bidding to the Bid class
and created ano_self_bidding` method in the same class. You can see this custom validation, along with a few others:
class Bid < ActiveRecord::Base belongs_to :user belongs_to :listing validates_presence_of :user_id validates_presence_of :listing_id validate :no_self_bidding validate :amount_higher_than_current_price validate :auction_isnt_over def no_self_bidding if self.user == self.listing.user errors.add(:user_id, "can't bid on your own item :)") end end def amount_higher_than_current_price if !self.amount || self.listing.current_price > self.amount errors.add(:amount, "must be higher than current price") end end def auction_isnt_over # if end time is in the past, add error if self.listing.over? errors.add(:base, "auction is over") end end end