Getting started

Usage

Removal strategy definition is called Plan. Plan is created using DSL. Plan can be validated and executed.

Plan defines a list of attributes and relations to clear. Relations work as nested Plans and can be nested infinitely.

Given schema:

create_table "users" do |t|
  t.string "first_name"
  t.string "last_name"
  t.string "reset_password_token"
  t.string "access_tokens"
  t.datetime "confirmed_at"
  t.integer "sign_in_count"
end

create_table "comments" do |t|
  t.integer "user_id"
  t.string "value"
end

create_table "resource_files" do |t|
  t.integer "comment_id"
end

create_table "dashboards" do |t|
  t.integer "user_id"
  t.string "order"
end

and models

class User < ActiveRecord::Base
 has_many :comments
 has_one :dashboard
end

class Comment < ActiveRecord::Base
  has_many :resource_files
end

class ResourceFile < ActiveRecord::Base; end
class Dashboard < ActiveRecord::Base; end

Example Plan:

UserWipeOutPlan = WipeOut.build_plan do
   # Set nil value by default
   wipe_out :first_name, :last_name
   # Custom strategy
   wipe_out :sign_in_count, strategy: WipeOut::AttributeStrategies::ConstValue.new(0)
   # Inline custom strategy
   wipe_out :reset_password_token do
     "random-value-#{SecureRandom.hex}"
   end

   # has_many relation
   relation :comments do
     # Behaves like nested Plan.
     wipe_out :value, strategy: WipeOut::AttributeStrategies::Randomize.new

     relation :resource_files do
      on_execute ->(execution) { execution.record.destroy! }
      ignore_all
     end
   end

   # has_one relation
   relation :dashboard do
     wipe_out :order
     ignore :name
   end

   # Ignore is used to mark both ignored relations
   # and ignored attributes
   ignore :access_tokens, :confirmed_at
end

After executing on a record

record = User.last
UserWipeOutPlan.execute(record)

User's:

• first_name and last_name attributes are set to nil value
• sign_in_count is set to 0
• reset_password_token is randomized
• access_tokens and confirmed_at attributes are not changed

User's Comments:

• value is randomized
• Comment's resource_files are all destroyed

User's dashboard:

• order attribute is set to nil
• name attribute is ignored

Validation

Plans can be validated against DB schema:

UserWipeOutPlan.validate(User)
UserWipeOutPlan.validate(User).errors
UserWipeOutPlan.validate(User).valid?

Method performs validation. It will contain errors if plan is invalid.

When new attribute is added to schema or a new relation is added to a model that is used in Plan then validation will fail.

Ignoring

Every relation or attribute which is not part of removal plan has to be marked as ignored with ignore.

through and belongs_to relations are ignored automatically and they don't have to be ignored manually.

By default these attributes are ignored:

• id
• created_at
• updated_at
• archived_at

Given schema:

create_table "users" do |t|
  t.string "first_name"
  t.string "last_name"
  t.integer "company_id"
  t.datetime "created_at"
  t.datetime "updated_at"
end

and class:

class User < ActiveRecord::Base
  belongs_to :company
  has_many :comments
  has_one :dashboard
  has_many :resource_files, through: :comments
end

a Plan to handle removing of this object has to provide strategy or ignore:

• attributes:

  • first_name
  • last_name
  • company_id

• relations:

  • comments
  • dashboard

Plan can skip providing strategy for:

• attributes id, created_at, updated_at - ignored by default
• relation company - belongs_to relation
• relation resource_files - through relation

Reusing Plans

Extracting

Nested plans can be extracted as independent object. An exemplary plan can be rewritten to:

CommentsWipeOutPlan = WipeOut.build_plan do
  wipe_out :value, strategy: WipeOut::AttributeStrategies::Randomize.new

  relation :resource_files do
    on_execute ->(execution) { execution.record.destroy! }
    ignore_all
  end
end

DashboardWipeOutPlan = WipeOut.build_plan do
  relation :dashboard do
    wipe_out :order
    ignore :name
  end
end

UserWipeOutPlan = WipeOut.build_plan do
  # …
  relation :comments, CommentsWipeOutPlan
  relation :dashboard, DashboardWipeOutPlan
  # …
end

Including

Plan can be included to other existing Plan. When Plan is included then its strategy is copied and extends current definition.

E.g.

HasAttachmentsPlan = WipeOut.build_plan do
  relation(:images) do
    on_execute ->(execution) { execution.record.destroy! }
    ignore_all
  end
  relation(:videos) do
    on_execute ->(execution) { execution.record.destroy! }
    ignore_all
  end
  wipe_out :attachments_count
end

WipeOut.build_plan do
  include_plan HasAttachmentsPlan
  relation(:comments) do
    wipe_out :content
    include_plan HasAttachmentsPlan
  end
end

is exactly the same as:

WipeOut.build_plan do
  wipe_out :attachments_count

  relation(:images) do
    on_execute ->(execution) { execution.record.destroy! }
    ignore_all
  end
  relation(:videos) do
    on_execute ->(execution) { execution.record.destroy! }
    ignore_all
  end

  relation(:comments) do
    wipe_out :content, :attachments_count

    relation(:images) do
      on_execute ->(execution) { execution.record.destroy! }
      ignore_all
    end
    relation(:videos) do
      on_execute ->(execution) { execution.record.destroy! }
      ignore_all
    end
  end
end

Dynamic plan selection

In some cases relation needs to have multiple Plan depending on the record's state. The list of Plans have to be known upfront to provide static validation. During Plan execution callback is called determine which Plan from the defined list to use for a given record.

UserPlan = WipeOut.build_plan do
  normal_plan = WipeOut.build_plan do
    on_execute ->(execution) { execution.record.destroy! }
  end
  vip_plan = WipeOut.build_plan do
    ignore … # do not remove all data yet
  end

  relation(:resource_files, plans: [vip_plan, normal_plan] do |resource_file|
    resource_file.user.vip? ? vip_plan : normal_plan
  end
end

Plugins

Plugins are used to define behaviours which are not supported by the core library.

Plugins usage can be defined by including them in a plan block.

Currently the only hooks available are:

• before(:plan) { |execution| ... } - called before plan execution, already in transaction
• after(:plan) { |execution| ... } - called after plan execution, still in transaction, last place to rollback
• before(:execution) { |execution| ... } - called before record is wiped out
• after(:execution) { |execution| ... } - called after record is wiped out

When Plan with plugins is nested inside other Plan (see "Reusing plans") then its plugins are ignored.

E.g. in scenario:

XPlan = WipeOut.build_plan do
  plugin PluginX
  wipe_out …
end

YPlan = WipeOut.build_plan do
  relation :x, XPlan
end

plugin defined in XPlan is completely ignored and not used.

Configuration

WipeOut global settings can can be configured:

WipeOut.config do |config|
  config.ignored_attributes << :user_id # defaults: [:id, :updated_at, :created_at, :archived_at]
end

Plans can override global config:

WipeOut.build_plan do
  configure do |config|
    config.ignored_attributes += [:some, :attributes]
  end
end

Similarly to Plugins, when Plan with config override is nested inside other Plan (see "Reusing plans") then its custom configuration is ignored.