Finite State Machine

gem 'aasm'

• add a aasm state field to the campaign model

g migration add_aasm_state_to_campaigns aasm_state:string:index

• migration file looks like this:

class AddAasmStateToCampaigns < ActiveRecord::Migration
  def change
    add_column :campaigns, :aasm_state, :string
    add_index :campaigns, :aasm_state
  end
end

• rake db migrate
• add the following to the campaign model

include AASM
  # setting the whiny_transitions: false option makes it so that it won't
  # throw an exception when an invalid transition happen
  aasm whiny_transitions: false do
    state :draft, initial: true
    state :published
    state :unfunded
    state :funded
    state :canceled

    event :publish do
      transitions from: :draft, to: :published
    end

    event :cancel do
      transitions from: [:draft, :published, :funded], to: :canceled
    end

    event :fund do
      transitions from: :published, to: :funded
    end

    event :unfund do
      transitions from: :published, to: :unfunded
    end
  end

• set the transition state

2.2.3 :008 >   c.draft?
true
2.2.3 :009 > c.published?
false
2.2.3 :010 > c.published!
   (0.2ms)  BEGIN
  Campaign Exists (0.4ms)  SELECT  1 AS one FROM "campaigns" WHERE ("campaigns"."name" = 'Hello try reward' AND "campaigns"."id" != 8) LIMIT 1
  SQL (0.3ms)  UPDATE "campaigns" SET "aasm_state" = $1, "updated_at" = $2 WHERE "campaigns"."id" = $3  [["aasm_state", "published"], ["updated_at", "2016-03-16 20:44:09.409139"], ["id", 8]]
  FriendlyId::Slug Load (0.2ms)  SELECT  "friendly_id_slugs".* FROM "friendly_id_slugs" WHERE "friendly_id_slugs"."sluggable_id" = $1 AND "friendly_id_slugs"."sluggable_type" = $2  ORDER BY "friendly_id_slugs".id DESC LIMIT 1  [["sluggable_id", 8], ["sluggable_type", "Campaign"]]
   (1.3ms)  COMMIT
true
2.2.3 :011 >

only show campaigns that are published on the index page

• have a method in campaign model

def published
    where(aasm_state: :published)
  end

• now change the index action in controller

def index
    # @campaigns = Campaign.all
    @campaigns = Campaign.order("created_at ASC").published
  end

• better to create new controller for showing only user's own campaigns

$ rails g controller my_campaigns

• routes

  resources :my_campaigns, only: [:index]

• in _header.html.erb, add in a link to only show user's campaigns

<%= link_to "Campaigns", my_campaigns_path %>

• add in the following view

<% @campaigns.each do |c| %>
<div class="well">
  <%= link_to c.name, c %>
  <p><%= c.description.truncate(100) %></p>
  <% end %>
</div>

• show campaign's state on campaign show page

<div class="label label-default">
  <%= @campaign.aasm_state %>
</div>

To publish a campaign

• create a new controller

rails g controller publishings

• nest publishing routes inside campaigns

  resources :campaigns do
    resources :pledges, only: [:create, :destroy]
    resources :publishings, only: [:create]
  end

• add a button on campaign show page which will publish this campaign

<% if @campaign.draft? %>
<%= link_to "Publish", campaign_publishing_path(@campaign), method: :post, class: "btn btn-primary", data: {confirm: "are you sure? you won't be able to edit a campaign after it's pubhlished"} %>
<% end %>