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
Author
user-image
Sujay
Rails templates accept any locals as arguments. However, starting from Rails 7.1, we can restrict which locals a template must accept using "Strict Locals".


Code

// _search.html.erb

<# locals: (:url, :field_name, :placeholder) -%>


We can also set default values

Code

<# locals: (placeholder: "Search", :url, :field_name) -%>


#rails
Published
Author
user-image
Adithya Hebbar
System Analyst
Detecting a mobile browser using regex.

You can use regex which returns a true or false value depending on whether or not the user is browsing with a mobile. WOW!

Code

window.mobilecheck = function () {
  var mobileCheck = false;
  (function (a) {
    if (
      /(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|mobile.+firefox|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows ce|xda|xiino/i.test(
        a
      ) ||
      /1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(
        a.substr(0, 4)
      )
    )
      mobileCheck = true;
  })(navigator.userAgent || navigator.vendor || window.opera);
  return mobileCheck;
};


I wonder who in the world wrote this snippet!!! :)

#javascript #browser
Published
Author
user-image
Syed Sibtain
System Analyst
Ransack adds several class methods to ActiveRecord::Base for managing search and sort capabilities. These methods allow us to define which attributes, associations, and scopes are accessible through Ransack queries, thus enhancing security and control.

ransackable_attributes: Defines which model attributes can be used in Ransack searches.
For example, only the order_number, status, and business_unit fields can be used in Ransack searches.

Code

def self.ransackable_attributes(auth_object = nil)
    %w[order_number status business_unit]
  end


ransackable_associations: Specifies which model associations are accessible for searching.
For examle, only the customer and vendor associations are allowed for searching.

Code

def self.ransackable_associations(auth_object = nil)
    %w[customer vendor]
  end


ransortable_attributes: Lists which attributes can be used for sorting results.
In this example, sorting is allowed only by order_number and created_at

Code

def self.ransortable_attributes(auth_object = nil)
    %w[order_number created_at]
  end


ransackable_scopes: Determines which custom scopes can be applied in searches.

#rails #ransack #search
Published
Author
user-image
Sujay
In postgres, current_setting() function is used to get the value of a configuration parameter.

Code

Set rls.tenant_id = 1;
SET

select current_setting('rls.tenant_id');
 current_setting
-----------------
 1
(1 row)


#postgres
Published
Author
user-image
Syed Sibtain
System Analyst
Namespaces in Rails help organize our application by grouping related controllers, models, and views into separate directories. Using namespaces with scaffolding keeps our codebase structured and manageable, especially in larger applications.

Example.
rails generate scaffold Order::PurchaseOrder order_number:string business_unit:string ...

This will create files under the Order namespace, including controllers, models, and views. This approach keeps our codebase structured, with Order as a namespace, making it easier to manage related components and maintain clarity in larger applications.


Code

app/
├── controllers/
│   └── order/
│       └── purchase_orders_controller.rb
├── models/
│   └── order/
│       └── purchase_order.rb
├── views/
│   └── order/
│       └── purchase_orders/
│           ├── _form.html.erb
│           ├── edit.html.erb
│           ├── index.html.erb
│           ├── new.html.erb
│


#rails #namespace
Published
Author
user-image
Vaibhav Yadav
Senior System Analyst
Cross browser regular expression issue:

Recently I came across a regular expression that would cause the page to crash on iphone Safari browser, the regex was for obscuring email.

Problematic Regex:

Code

const obscuredEmail = email.replace(/(?<=.1}).(?=[^@]*@)/g, '*');


Fix:

Code

const obscuredEmail = email.replace(/(.)(?=.*@)/g, (match, p1, offset, string) => offset < string.indexOf('@') - 1 ? '*' : p1);


Lesson: Even a browser can cause browser compatibility issues.

#regex #browserCompatibility #safari #javascript
Published
Author
user-image
Sachin Kabadi
System Analyst
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.

Code

# 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:

Code

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


Create a file that reopens the class:

Code

# 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
Published
Author
user-image
Sujay
Remove the published gem from rubygems using

Code

gem yank GEM -v VERSION


#rails #rubygems
Published
Author
user-image
Satya
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.

Code

<%= 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
Published
Author
user-image
Sujay
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)

Code

s.add_dependency "pagy"


#rails #rails-engines

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