Add Follow.unfollowed_at

The active scopes is used indirectly in the dossier<->gestionnaire associations: the existing tests in dossier and gestionnaire just work™.

app/models/dossier.rb

@@ -26,7 +26,7 @@ class Dossier < ApplicationRecord
   has_many :champs_private, -> { root.private_only.ordered }, class_name: 'Champ', dependent: :destroy
   has_many :commentaires, dependent: :destroy
   has_many :invites, dependent: :destroy
-  has_many :follows
+  has_many :follows, -> { active }
   has_many :followers_gestionnaires, through: :follows, source: :gestionnaire
   has_many :avis, dependent: :destroy
 

app/models/follow.rb

@@ -2,10 +2,12 @@ class Follow < ApplicationRecord
   belongs_to :gestionnaire
   belongs_to :dossier
 
-  validates :gestionnaire_id, uniqueness: { scope: :dossier_id }
+  validates :gestionnaire_id, uniqueness: { scope: [:dossier_id, :unfollowed_at] }
 
   before_create :set_default_date
 
+  scope :active, -> { where(unfollowed_at: nil) }
+
   private
 
   def set_default_date

app/models/gestionnaire.rb

@@ -16,7 +16,7 @@ class Gestionnaire < ApplicationRecord
   has_many :procedures_with_email_notifications, through: :assign_to_with_email_notifications, source: :procedure
 
   has_many :dossiers, -> { state_not_brouillon }, through: :procedures
-  has_many :follows
+  has_many :follows, -> { active }
   has_many :followed_dossiers, through: :follows, source: :dossier
   has_many :avis
   has_many :dossiers_from_avis, through: :avis, source: :dossier
@@ -40,7 +40,10 @@ class Gestionnaire < ApplicationRecord
   end
 
   def unfollow(dossier)
-    followed_dossiers.delete(dossier)
+    f = follows.find_by(dossier: dossier)
+    if f.present?
+      f.update(unfollowed_at: Time.zone.now)
+    end
   end
 
   def follow?(dossier)

db/migrate/20190607124156_add_follow_unfollowed_at.rb

@@ -0,0 +1,17 @@
+class AddFollowUnfollowedAt < ActiveRecord::Migration[5.2]
+  # We need up/down migrations because `remove_index` doesn’t allow `unique: true` and can’t be properly rolled back.
+  def up
+    add_column :follows, :unfollowed_at, :datetime
+
+    remove_index :follows, [:gestionnaire_id, :dossier_id]
+    add_index :follows, [:gestionnaire_id, :dossier_id, :unfollowed_at], unique: true,
+      name: :uniqueness_index # We need a custom name because the autogenerated name would be too long
+  end
+
+  def down
+    remove_column :follows, :unfollowed_at
+    # We don’t need to remove the index: dropping the column automatically deletes it.
+
+    add_index :follows, [:gestionnaire_id, :dossier_id], unique: true
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_06_07_122941) do
+ActiveRecord::Schema.define(version: 2019_06_07_124156) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -333,8 +333,9 @@ ActiveRecord::Schema.define(version: 2019_06_07_122941) do
     t.datetime "messagerie_seen_at", null: false
     t.datetime "created_at"
     t.datetime "updated_at"
+    t.datetime "unfollowed_at"
     t.index ["dossier_id"], name: "index_follows_on_dossier_id"
-    t.index ["gestionnaire_id", "dossier_id"], name: "index_follows_on_gestionnaire_id_and_dossier_id", unique: true
+    t.index ["gestionnaire_id", "dossier_id", "unfollowed_at"], name: "uniqueness_index", unique: true
     t.index ["gestionnaire_id"], name: "index_follows_on_gestionnaire_id"
   end