Fueling Curiosity, One Insight at a Time

ActiveSupport::CurrentAttributes provides a thread-isolated attributes singleton, perfect for request-specific data like current user, role, or locale.
create a current.rb in models directory and add the attributes we want to set

class Current < ActiveSupport::CurrentAttributes
  attribute :role
end

then in application controller we can set it like this

class ApplicationController < ActionController::Base  
  before_action :set_current_attributes

  def set_current_attributes
    Current.role = session[:role]
    // ... other attributes
  end
end

now in your application we can directly access and use like Current.role

#CU6U0R822 #rails-current-attributes

Mise

Mise is a fast, lightweight (thanks to Rust :happy_pepe:), language agnostic version manager that can be used instead of having separate language based version managers like rbenv for Ruby, npm for Node.js and Pyenv for Python etc.

Installing a Ruby version globally is as simple as follows:

mise use -g ruby@3

Installing mise is as easy as following in MacOS

curl https://mise.run | sh

Proceed with following to configure the Shell Initialisation

echo 'eval "$(~/.local/bin/mise activate)"' >> ~/.zshrc

Reload the shell configuration changes in current tab

source ~/.zshrc

#mise #ruby-version-manager #version-manager #C04HPTKNZ8R #ruby #python #CCT1JMA0Z

mattr_accessor is a Rails utility method that creates a class-level accessor for a variable.
When we define mattr_accessor for a variable, it creates
1. A getter method for the class.
2. A setter method for the class.
Eg:

class MyClass
  mattr_accessor :my_variable
end

This is equivalent to:

class MyClass
  @my_variable = nil

  def self.my_variable
    @my_variable
  end

  def self.my_variable=(value)
    @my_variable = value
  end
end

It also works on module-level classes, which makes it particularly useful for defining global configuration in gems.

#CU6U0R822

accepts_nested_attributes_for is a Rails method that allows you to easily manage the creation, updating, and destruction of associated models through the parent model's attributes. This is particularly useful when you have nested forms or when you want to handle multiple models in a single operation (e.g., creating or updating a User and its associated Profile in one form submission).

class User < ApplicationRecord
  has_one :profile
  accepts_nested_attributes_for :profile
end

Given the User model has a has_one :profile association, and you want to create or update a User and their Profile at the same time, you can use accepts_nested_attributes_for to pass attributes for both models:

user_params = {
  name: "John Doe",
  profile_attributes: { bio: "Developer", age: 30 }
}

user = User.create(user_params)

In this example, Rails will create both a new User and a new Profile with the attributes provided in profile_attributes.
#CU6U0R822

When working with paginated data in Ruby on Rails, we might encounter situations where we need to paginate an array rather than an Active Record collection. The pagy gem provides an efficient and flexible way to handle pagination, and it includes an extras/array feature specifically for arrays.

Require the Pagy Extras Array:

# config/initializers/pagy.rb

require "pagy/extras/array"

And then use the pagy_array method to paginate your array in the controller

def index
 // some code
 @pagy, @purchase_order_attachments = pagy_array(orders_with_attachments, items: params[:limit] || 10)
end

#rubyonrails #pagination #pagy

In Python, dir() lists the attributes and methods of an object, such as a class or instance.

Example:

class MyClass:
    class_variable = "Class Variable"

    def __init__(self):
        self.instance_variable = "Instance Variable"

    def my_method(self):
        pass

obj = MyClass()
print(dir(obj))

Output:
dir(obj) shows a list of attributes (class_variable, instance_variable) and methods (my_method), along with special methods (e.g., __init__). It helps explore what’s available in an object.

Test SSH connection detailed logs to debug #ssh #CCTJN6PK4

ssh -vT "git@gitlab.com"

This will output detailed logs

Definite Assignment Checks in TypeScript 5

• Before TypeScript 5:

let value: string;
console.log(value); // TS4.x: This was allowed but could lead to runtime undefined

• After TypeScript 5:

let value: string;
console.log(value); // TS5.x: Error - Variable 'value' is used before being assigned

// To fix, either initialize:
let value = "initial";

// Or use definite assignment assertion:
let value!: string;

• The ! is a promise to TypeScript that we'll assign a value before using it
• Use of ! should be avoided as it bypasses TypeScript's safety checks

When working with routes in a Rails application that includes an engine, route references need to be scoped appropriately based on where they are being called:
• Referencing engine routes from outside the engine: Prefix the route with the engine's name. For example, use engine_name.some_route_path (e.g., rapidfire.surveys_path) to access routes within the engine.
• Referencing routes from another engine: Use the other engine's name as a prefix, similar to referencing routes from outside.
This naming ensures the correct routing context and prevents conflicts when multiple engines or the main application define similar paths.

#CU6U0R822 #routes

Form Objects in Rails
Form objects are a pattern that is used to encapsulate logic for managing and validating form data. They act as an intermediary between the view and the model layer, they simplify the handling of complex forms, particularly when working with complex forms that don't map to a single active record model.
Why use form objects?
In typical rails applications, forms are directly tied to active record models. This is ok when the forms are simple, but this can cause problem when complexity increases such as,
when forms interact with multiple models
In these kind of scenarios, we can encapsulate the corresponding logic into a single class which acts like an active record model which is easier to maintain.

Example form object
app/forms/route_request_form.rb

class UserProfileForm
  include ActiveModel::Model

 # Attributes accessible for the form object.
  attr_accessor :user_name, :email, :profile_bio, :profile_age

  validates :user_name, :email, presence: true
  validates :profile_age, numericality: { only_integer: true, greater_than: 0 }

  def save
    return false unless valid?
    
    #a single transaction for multiple operations
    ActiveRecord::Base.transaction do
      user = User.create!(name: user_name, email: email)
      user.create_profile!(bio: profile_bio, age: profile_age)
    end

    true # Return true if all operations succeed.
  rescue ActiveRecord::RecordInvalid
    false # Return false if the save process fails.
  end
end

Using it in controller

class UsersController < ApplicationController
  def new
    @form = UserProfileForm.new
  end

  def create
    @form = UserProfileForm.new(user_profile_form_params)

    if @form.save
      redirect_to root_path, notice: "User created successfully!"
    else
      render :new, status: :unprocessable_entity
    end
  end

  private

  def user_profile_form_params
    params.require(:user_profile_form).permit(:user_name, :email, :profile_bio, :profile_age)
  end
end

#ruby_on_rails #form_objects