Pros of Squeel

• More expressive and readable query syntax
• Supports complex nested conditions and joins
• Allows for dynamic query building with less code

Cons of Squeel

• Not actively maintained (last commit in 2017)
• May have compatibility issues with newer Rails versions
• Steeper learning curve for developers familiar with standard ActiveRecord queries

Code Comparison

Arel:

User.where(User.arel_table[:name].matches('%John%'))
  .joins(:posts)
  .where(Post.arel_table[:title].matches('%Ruby%'))

Squeel:

User.where{name.like '%John%'}
  .joins{posts}
  .where{posts.title.like '%Ruby%'}

Summary

Squeel provides a more intuitive and flexible syntax for complex queries compared to Arel. It allows for easier nested conditions and dynamic query building. However, Squeel's lack of recent updates and potential compatibility issues with newer Rails versions are significant drawbacks. Arel, being part of the Rails core, offers better long-term support and integration with ActiveRecord, albeit with a more verbose syntax for complex queries. Developers should consider their project's specific needs and the trade-offs between expressiveness and long-term maintainability when choosing between these libraries.

Pros of Hanami

• Modular architecture: Hanami is designed with a focus on modularity, allowing developers to use only the components they need.
• Lightweight: Hanami has a smaller footprint and faster boot times compared to Rails.
• Emphasis on clean code: Hanami encourages better code organization and separation of concerns.

Cons of Hanami

• Smaller community: Hanami has a less extensive ecosystem and fewer available gems compared to Rails.
• Steeper learning curve: Developers familiar with Rails may need time to adapt to Hanami's different conventions.
• Less documentation: Hanami has fewer resources and tutorials available online.

Code Comparison

Hanami route definition:

get '/hello', to: 'hello#index'

Arel query construction:

users = User.arel_table
query = users.project(users[:name]).where(users[:age].gt(18))

While Arel is specifically focused on SQL generation and query building, Hanami is a full-stack web framework. Arel is actually a dependency of Rails and is used internally for database querying. Hanami, on the other hand, provides its own query interface that is different from both Rails and Arel.

Hanami aims to provide a more modular and lightweight alternative to Rails, while Arel serves as a powerful SQL generation engine used within Rails. The choice between them depends on whether you need a full framework (Hanami) or just a SQL abstraction layer (Arel).

Pros of ROM

• More flexible and modular architecture, allowing for easier customization and extension
• Supports multiple data sources beyond just SQL databases (e.g., CSV, YAML, MongoDB)
• Provides a cleaner separation of concerns between data access and business logic

Cons of ROM

• Steeper learning curve compared to Arel's more Rails-integrated approach
• Smaller community and ecosystem, potentially leading to fewer resources and plugins
• May require more setup and configuration for basic use cases

Code Comparison

ROM example:

class Users < ROM::Relation[:sql]
  schema(infer: true)

  def by_name(name)
    where(name: name)
  end
end

Arel example:

users = User.arel_table
query = users.where(users[:name].eq('John'))
User.find_by_sql(query.to_sql)

Summary

ROM offers greater flexibility and support for multiple data sources, while Arel provides tighter integration with Rails and a potentially gentler learning curve. ROM's modular design allows for more customization, but Arel's larger ecosystem may offer more immediate solutions for common use cases. The choice between the two depends on project requirements, team expertise, and desired level of abstraction in data access layers.