TILs - Fueling Curiosity, One Insight at a Time

At Codemancers, we believe every day is an opportunity to grow. This section is where our team shares bite-sized discoveries, technical breakthroughs and fascinating nuggets of wisdom we've stumbled upon in our work.

Published
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Aditya Vishwakarma
System Analyst
We can't use turbo frame for table rows, because html doesn't allow external tag like turbo frame inside the table.

The workaround this is to just have unique id for element you want to modify and use turbosteam to modify only that element.

#rubyonrails #turbo #turboframes #spa
Published
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Satya
in ruby https://nil.to|nil.to_i => 0 & https://nil.to|nil.to_f => 0.0
#ruby, #nil-conversion
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Sujay
Steps to merge one repo into another

Step 1: Clone Repo1 locally

Code

git clone  repo1
cd repo1


Step 2: Fetch all the branches and commits from Repo2

Code

git remote add repo2 
git fetch repo2


Step 3: Create a branch

Code

git checkout -b merge-repo2


Step 4: Merge keeping full history

Code

git merge --allow-unrelated-histories repo2/main (Since the repositories have separate histories, this option allows Git to combine them, potentially requiring manual conflict resolution)


Step 5: Resolve Merge Conflicts

Code

git add .
git commit -m "Resolved merge conflicts"


#git
Published
Author
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Mohammad hussain
System Analyst
pagy_array This method is the same as the generic pagy method, but specialized for an Array.

Code

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


#CU6U0R822 #ruby
Published
Author
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Mohammad hussain
System Analyst

```
pagy_array
Published
Author
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Nived Hari
System Analyst
each_with_object is an enumerable method in Ruby that allows you to iterate over a collection while building up an object (like an array or hash). Unlike map, which creates a new array, each_with_object lets you modify an existing object in a single pass.

Syntax

Code

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


• collection: The array or enumerable you're iterating over.
• initial_object: The object that will be modified (e.g., {} for a hash or [] for an array).
• item: The current element in the iteration.
• object: The object that accumulates the results.
Example Usage
Using each_with_object with a Hash

Code

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}


Why use each_with_object?
• Avoids the need to initialize an empty {} before the loop.
• Eliminates the need to return the object explicitly.

#CU6U0R822 #ruby
Published
Author
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Mohammad hussain
System Analyst
When to use collection_select over select in rails
Use collection_select when you need to populate a dropdown with a collection of ActiveRecord objects. It is built on top of select and provides a convenient way to display object attributes instead of a simple array of strings.
select is used for manually defining options, typically from an array of strings or key-value pairs.
collection_select is specifically designed for selecting records from an ActiveRecord collection, making it useful when working with database associations.
Published
Author
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Nived Hari
System Analyst
Rake tasks in Rails let you run custom scripts from the command line.
You can define your own tasks inside the lib/tasks directory.

How to Create a Custom Rake Task

1. Create a new .rake file in lib/tasks/

Code

touch lib/tasks/custom_tasks.rake


Define the task inside the file:

Code

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


Run the task from the terminal:

Code

bin/rake custom:hello


Use :environment if your task interacts with the database or models

#CU6U0R822 #rake
Published
Author
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Nived Hari
System Analyst
The inverse_of option in ActiveRecord helps Rails recognize bidirectional associations in memory, reducing redundant database queries.
For example:

Code

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


Why Use inverse_of?
• Prevents extra queries when accessing related objects
• Keeps objects in memory, improving performance
• Ensures associated objects reference the same instance
Without inverse_of, Rails may reload the association unnecessarily:


Code

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


With inverse_of, Rails avoids the extra query because it knows department.employees already includes employee

#CU6U0R822 #active_record
Published
Author
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Nived Hari
System Analyst
In dry-validation contracts, values is a hash containing all the parameters being validated. When defining rule blocks, you can access specific parameters using hash-like syntax.
Example:

Code

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


Key Points:
• values holds all input parameters.
• Use values[:key] to access specific parameters inside rule blocks.
• This allows custom validation logic beyond basic schema definitions.
#ruby #dry_validation

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