Fueling Curiosity, One Insight at a Time

How to override models in parent application by reopening existing Rails engine classes. This can be done by organising overrides in a dedicated directory (e.g., app/overrides), ignoring this directory in the autoloader, and preloading the overrides in a to_prepare callback.

# config/application.rb
module MyApp
  class Application < Rails::Application
    # ...

    overrides = "#{Rails.root}/app/overrides"
    Rails.autoloaders.main.ignore(overrides)

    config.to_prepare do
      Dir.glob("#{overrides}/**/*_override.rb").sort.each do |override|
        load override
      end
    end
  end
end

To override an engine model, such as Blog::Article:

# Blog/app/models/blog/article.rb
module Blog
  class Article < ApplicationRecord
    # ...
  end
end

Create a file that reopens the class:

# MyApp/app/overrides/models/blog/article_override.rb
Blog::Article.class_eval do
  # ...
end

Using class_eval ensures we are reopening the class or module, not redefining it.

#rails #rails-engines

Remove the published gem from rubygems using

gem yank GEM -v VERSION

#rails #rubygems

while using form.file_field for file attachments we can restrict the file type to any type if we want.
For eg: if we want to accept file of type image then we can pass accept attribute.

 <%= form.file_field :picture, accept: "image/*" %>

Note: This will disable other file types in your local file dialog while enabling the image files only 🪄 .
#rails , #active-storage

To ensure a dependency is installed with the engine during gem install, it must be specified within the Gem::Specification block inside the engine's .gemspec file (e.g., blog.gemspec for an engine named Blog, located at the root)

s.add_dependency "pagy"

#rails #rails-engines

In Rails, gems are libraries that add specific functionality to a Rails application. They can be used across different projects and typically do not have their own structure or generators.
Examples include devise for authentication and nokogiri for XML parsing.

Engines, on the other hand, are miniature Rails applications that can have their own routes, controllers, models, and views. They are used to encapsulate and modularize specific features or components within a Rails app. An engine can be packaged as a gem, but it provides more extensive, self-contained functionality compared to a typical gem.

#rails

A Rails engine is a pattern used to modularize a Rails application. These engines are self-contained applications with their own models, views, controllers, and routes, allowing them to function autonomously. They can be integrated into a larger Rails application. For example, in an e-commerce application, modules like orders, products, users, and payments can each be separate engines.
#rails

Resolving gen_random_uuid() Error with PostgreSQL While Implementing CI
When configuring CI with GitHub Actions, I encountered the following error:

PG::UndefinedFunction: ERROR:  function gen_random_uuid() does not exist

This error occurred because the gen_random_uuid() function is not available in PostgreSQL versions older than 11. UUID generation functions were only available through external modules like uuid-ossp and pgcrypto in these older versions.

To resolve this issue, I upgraded to PostgreSQL 13, which includes the gen_random_uuid() function to generate version-4 UUIDs. After upgrading, the error was resolved.



#rails #postgresql #uuid #ci-cd #github-actions

Jupyter Labs

• To install Jupyter Labs in Mac using Homebrew:

brew install jupyterlab

• To run Jupyter lab:

jupyter lab

This will open JupyterLab in your default web browser.

#python #homebrew

The fields_for helper in Rails creates form bindings without rendering a

tag. This is particularly useful for rendering fields for additional model objects within a single form.

Imagine you have a Book model with an associated Author model. You can create a single form for both the Book and Author models using the fields_for helper.

<%= form_with model: @book do |book_form| %>
  <%= book_form.text_field :title %>
  <%= book_form.text_area :description %>

  <%= fields_for :author, @book.author do |author_form| %>
    <%= author_form.text_field :name %>
    <%= author_form.text_field :email %>
  <% end %>
<% end %>

#rails #fields-for #rails-view

rails db:prepare in Ruby on Rails, This command sets up and prepares the database for my application, ensuring everything's ready to go, including populating the database.
#rails #databasesetup