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: Aug 27, 2024
Author: Adithya Hebbar
System Analyst

To logout from Keycloak using the signOut function in NextAuth, you need to override the default behavior to ensure that the user is properly logged out from Keycloak as well. Here's how you can update your signOut function:

Code

async signOut({ token }) {
  if (token.provider === "keycloak") {
    const issuerUrl = authOptions.providers.find((p) => p.id === "keycloak")
      .options!.issuer!;
    const logOutUrl = new URL(
      `${issuerUrl}/protocol/openid-connect/logout`
    );
    logOutUrl.searchParams.set("id_token_hint", token.id_token!);
    await fetch(logOutUrl);
  }
}

#keycloak #nextauth #nextjs #js

Published: Aug 8, 2024
Author: Giritharan
System Analyst

Delegating Permissions in Pundit:

I encountered a scenario where I needed to retrieve the scope of one policy and use it within another policy. Specifically, I wanted to delegate permissions from one policy to another.

To address this issue, I learned to use Pundit's methods for manually retrieving policies and scopes:
• Retrieving a Policy

Code

Pundit.policy(user, record)  # Returns nil if the policy does not exist
Pundit.policy!(user, record) # Raises an exception if the policy does not exist

• Retrieving a Policy Scope:

Code

Pundit.policy_scope(user, ModelClass)  # Returns nil if the policy scope does not exist
Pundit.policy_scope!(user, ModelClass) # Raises an exception if the policy scope does not exist

These methods allowed me to delegate permissions effectively by retrieving and applying the appropriate scopes and policies

#rails #pundit #pundit-policy #authorization

Published: Aug 7, 2024
Author: Syed Sibtain
System Analyst

Quick Tip: How can we open a PR from one repository to another repository

1. Create the branch in the current repo

Code

git checkout -b new-branch

2. Add the destination repository as a remote.

Code

git remote add destination https://github.com/username/destination-repo.git

3. Push the new branch to the destination repository

Code

git push destination new-branch

4. To check all the remote repositories added, we can do:

Code

git remote -v

Then, we create a PR in the destination repository from the new branch. This process effectively copies the changes from the original PR into a new PR in a different repository.

#github #git

Published: Aug 6, 2024
Author: 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: Aug 3, 2024
Author: 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: Aug 2, 2024
Author: 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: Aug 2, 2024
Author: 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: Jul 31, 2024
Author: 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: Jul 30, 2024
Author: 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: Jul 29, 2024
Author: 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

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