Strategies for Migrating from Rails 5 to 7 while Maintaining Legacy Support
Currently developing an MVP for our startup, we're in the process of migrating our application from Rails 5 to Rails 7. One significant challenge involves maintaining support for legacy code during this transition. I've noticed that some ActiveRecord models are reliant on deprecated methods, and I want to ensure we don't break existing functionality while introducing the new features from Rails 7. To tackle this, I've been considering two strategies. First, I thought about refactoring the models gradually, replacing deprecated methods with their Rails 7 counterparts. For instance, switching from `pluck` to `select` for fetching attributes. Here's a snippet of a model method that currently uses `pluck`: ```ruby # Rails 5 class User < ApplicationRecord def self.active_emails pluck(:email) end end ``` I would like to switch this to the Rails 7 approach, possibly incorporating `select` instead. But I want to avoid performance hits due to the transformation of large datasets. Additionally, there are some models that heavily use custom callbacks which might not behave as expected after the upgrade. The second approach I'm contemplating is to implement feature flags during the migration. By using a gem like `flipper`, I could toggle between legacy and new features without disrupting the user experience. The configurations could look like this: ```ruby # config/initializers/flipper.rb require 'flipper' Flipper.configure do |config| config[:my_feature] = true end ``` I’ve also looked into using `ActiveSupport::Deprecation` to help manage warnings in the code before fully removing deprecated methods. Would this be a recommended practice? Overall, I want to maintain a balance between updating our stack to leverage new Rails features while ensuring that current users have a seamless experience. Any advice on best practices, pitfalls to avoid, or insights on others who've successfully navigated this migration would be greatly appreciated. What are the common issues developers face during such transitions, and how did they resolve them? What's the correct way to implement this?