Class: RuboCop::Cop::Rails::BulkChangeTable

Inherits:

Base

• Object
• Base
• RuboCop::Cop::Rails::BulkChangeTable

Defined in:

lib/rubocop/cop/rails/bulk_change_table.rb

Overview

This Cop checks whether alter queries are combinable. If combinable queries are detected, it suggests to you to use `change_table` with `bulk: true` instead. This option causes the migration to generate a single ALTER TABLE statement combining multiple column alterations.

The `bulk` option is only supported on the MySQL and the PostgreSQL (5.2 later) adapter; thus it will automatically detect an adapter from `development` environment in `config/database.yml` when the `Database` option is not set. If the adapter is not `mysql2` or `postgresql`, this Cop ignores offenses.

Examples:

# bad
def change
  add_column :users, :name, :string, null: false
  add_column :users, :nickname, :string

  # ALTER TABLE `users` ADD `name` varchar(255) NOT NULL
  # ALTER TABLE `users` ADD `nickname` varchar(255)
end

# good
def change
  change_table :users, bulk: true do |t|
    t.string :name, null: false
    t.string :nickname
  end

  # ALTER TABLE `users` ADD `name` varchar(255) NOT NULL,
  #                     ADD `nickname` varchar(255)
end

# bad
def change
  change_table :users do |t|
    t.string :name, null: false
    t.string :nickname
  end
end

# good
def change
  change_table :users, bulk: true do |t|
    t.string :name, null: false
    t.string :nickname
  end
end

# good
# When you don't want to combine alter queries.
def change
  change_table :users, bulk: false do |t|
    t.string :name, null: false
    t.string :nickname
  end
end

See Also:

• https://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-change_table
• https://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/Table.html

Defined Under Namespace

Classes: AlterMethodsRecorder

Constant Summary

MSG_FOR_CHANGE_TABLE =

<<~MSG.chomp
  You can combine alter queries using `bulk: true` options.
MSG

MSG_FOR_ALTER_METHODS =

<<~MSG.chomp
  You can use `change_table :%<table>s, bulk: true` to combine alter queries.
MSG

MYSQL =

'mysql'

POSTGRESQL =

'postgresql'

MIGRATION_METHODS =

%i[change up down].freeze

COMBINABLE_TRANSFORMATIONS =

%i[
  primary_key
  column
  string
  text
  integer
  bigint
  float
  decimal
  numeric
  datetime
  timestamp
  time
  date
  binary
  boolean
  json
  virtual
  remove
  change
  timestamps
  remove_timestamps
].freeze

COMBINABLE_ALTER_METHODS =

%i[
  add_column
  remove_column
  remove_columns
  change_column
  add_timestamps
  remove_timestamps
].freeze

MYSQL_COMBINABLE_TRANSFORMATIONS =

%i[
  rename
  index
  remove_index
].freeze

MYSQL_COMBINABLE_ALTER_METHODS =

%i[
  rename_column
  add_index
  remove_index
].freeze

POSTGRESQL_COMBINABLE_TRANSFORMATIONS =

%i[
  change_default
].freeze

POSTGRESQL_COMBINABLE_ALTER_METHODS =

%i[
  change_column_default
].freeze

Instance Method Summary

• #on_def(node) ⇒ Object
• #on_send(node) ⇒ Object

Instance Method Details

#on_def(node) ⇒ Object

# File 'lib/rubocop/cop/rails/bulk_change_table.rb', line 134

def on_def(node)
  return unless support_bulk_alter?
  return unless MIGRATION_METHODS.include?(node.method_name)
  return unless node.body

  recorder = AlterMethodsRecorder.new

  node.body.child_nodes.each do |child_node|
    if call_to_combinable_alter_method? child_node
      recorder.process(child_node)
    else
      recorder.flush
    end
  end

  recorder.offensive_nodes.each { |n| add_offense_for_alter_methods(n) }
end

#on_send(node) ⇒ Object

# File 'lib/rubocop/cop/rails/bulk_change_table.rb', line 152

def on_send(node)
  return unless support_bulk_alter?
  return unless node.command?(:change_table)
  return if include_bulk_options?(node)
  return unless node.block_node

  send_nodes = node.block_node.body.each_child_node(:send).to_a

  transformations = send_nodes.select do |send_node|
    combinable_transformations.include?(send_node.method_name)
  end

  add_offense_for_change_table(node) if transformations.size > 1
end