TILs - Fueling Curiosity, One Insight at a Time

require 'pagy/extras/array'
@pagy, @items = pagy_array(an_array)

collection.each_with_object(initial_object) do |item, object|
  # Modify the object inside the block
end

numbers = [1, 2, 3, 4, 5]
squares = numbers.each_with_object({}) do |num, hash|
  hash[num] = num**2
end

puts squares
# Output: {1=>1, 2=>4, 3=>9, 4=>16, 5=>25}

touch lib/tasks/custom_tasks.rake

namespace :custom do
  desc "Say hello from a custom rake task"
  task :hello do
    puts "Hello from custom Rake task!"
  end
end

bin/rake custom:hello

class Employee < ApplicationRecord
  belongs_to :department, foreign_key: 'department_code', primary_key: 'code', inverse_of: :employees
end

class Department < ApplicationRecord
  has_many :employees, foreign_key: 'department_code', primary_key: 'code', inverse_of: :department
end

employee = Employee.first
department = employee.department  # Triggers a SQL query
department.employees.include?(employee)  # Without `inverse_of`, this could trigger another query

class MyContract < Dry::Validation::Contract
  params do
    required(:category).filled(:string)
  end

  rule(:category) do
    key.failure("is not allowed") unless values[:category] == "approved_value"
  end
end

payload = {
  id: 123,
  name: "Sample Item",
  status: "processed",
  timestamp: 
Time.now.to_i
}

Karafka.producer.produce_sync(
  topic: "your_topic_name",
  payload: payload.to_json
)