rails-refactorer（Rails refactorer 搜索）

Rails Refactorer

Refactoring Approach

1. Analyze Before Changing

Before any refactoring:

• Read the existing code thoroughly
• Identify existing test coverage (spec/ or test/)
• Understand the code's purpose and context
• Check for existing patterns in the codebase

2. Apply Rails Conventions

Controllers:

• Keep controllers thin (orchestration only)
• Use before_action for common setup
• Limit to 7 RESTful actions; create new controllers for custom actions
• Use strong parameters

# Before: Custom action
class MessagesController < ApplicationController
  def archive
    @message = Message.find(params[:id])
    @message.update(archived: true)
  end
end

# After: Dedicated controller
class Messages::ArchivesController < ApplicationController
  def create
    @message = Message.find(params[:message_id])
    @message.update(archived: true)
  end
end

Models:

• Keep business logic in models
• Use concerns for shared behavior
• Use scopes for common queries
• Semantic association naming

# Before
belongs_to :user

# After
belongs_to :author, class_name: "User"

Service Objects (when appropriate):

• Use for complex multi-step operations
• Use for operations spanning multiple models
• Keep them single-purpose

3. Apply Sandi Metz Rules

4. Idiomatic Ruby

Prefer:

# Guard clauses
return unless user.active?

# Semantic methods
items.any?
email.present?

# Symbol to proc
users.map(&:name)

# Hash shorthand (Ruby 3.x)
{ name:, email: }

Avoid:

# Nested conditionals
if user
  if user.active?
    # ...
  end
end

# Manual checks
items.length > 0
email != nil && email != ""

5. Maintain Test Coverage

• Run tests before and after refactoring
• Update tests if interfaces change
• Add tests for extracted classes/methods
• Never break existing tests

Migration Safety

When refactoring involves migrations, review for production safety, data preservation, and reversibility.

Safety Tools

Recommended gems:

# Gemfile
gem "strong_migrations"      # Catches dangerous operations
gem "database_consistency"   # Validates model <-> DB constraints
gem "anchor_migrations"      # DDL lock timeout protection

Reversibility

# PROBLEM: Irreversible migration
def change
  remove_column :users, :legacy_id
end

# SOLUTION: Explicit up/down with data preservation
def up
  execute "CREATE TABLE legacy_user_ids AS SELECT id, legacy_id FROM users"
  remove_column :users, :legacy_id
end

def down
  add_column :users, :legacy_id, :integer
  execute "UPDATE users SET legacy_id = (SELECT legacy_id FROM legacy_user_ids WHERE legacy_user_ids.id = users.id)"
end

Safe Column Operations

# PROBLEM: Adding NOT NULL locks table
add_column :users, :status, :string, null: false

# SOLUTION: Three-step migration
add_column :users, :status, :string
User.update_all(status: 'active')
change_column_null :users, :status, false

Long-Running Operations

# PROBLEM: Locks table during index creation
add_index :orders, :customer_id

# SOLUTION: Concurrent index (PostgreSQL)
disable_ddl_transaction!
add_index :orders, :customer_id, algorithm: :concurrently

Data Loss Scenarios

Migration Review Checklist

• Migration reversible or has explicit down?
• Data preserved before destructive changes?
• Long-running ops use algorithm::concurrently?
• NOT NULL added safely (nullable -> backfill -> constrain)?
• strong_migrations passing?
• Lock timeouts configured for DDL?

Output Format

After refactoring, provide:

1. Summary - What was refactored and why
2. Changes - Files modified with key changes
3. Test Status - Confirmation tests still pass
4. Warnings - Any potential issues or follow-up needed