TILs - Fueling Curiosity, One Insight at a Time

while tesing with enzyme if you are unit testing your component method with component.instance().methodName() always double check if the method that you are testing have access to "this" variable manually. Currently even if it does not have "this" access the test will pass

You can create a quick screencast using hangouts and then share the video as a private youtube video

fresh_when, more here https://medium.com/rubyinside/https-medium-com-wintermeyer-caching-in-ruby-on-rails-5-2-d72e1ddf848c

emacs has a "M-x base64-encode-region"

In ruby you can use any single non alpha numeric character as delimiter for % notation. The following are all same %(foo bar); %w[foo bar]; %w%foo bar%; %w$foo bar$; And many more. https://en.wikibooks.org/w/index.php?title=Ruby_Programming/Syntax/Literals#The_%_Notation

git bundle https://git-scm.com/docs/git-bundle

Rails 5 prevents accidental halting of the callbacks. In order to explicitly halt, we can make use of throw(:abort) in the callback chain.

Sidekiq by default does 25 retries (about 21 days) based on exponential back off formula ie. to retry multiple times with exponential delays. If need be, we can explicitly configure max_retries in sidekiq.yml.

while writing test for a parent component which renders child component based on some state/prop and if your child component is connected, always import unconnected child component and do assertion on that.
/code
import { ChildComponent } from 'path/to/component';

expect(component.find(ChildComponent).length).toBe(1);

//instead of
expect(component.find('ChildComponent').length).toBe(1);

In Rails we can do two modes of locking that is 'Optimistic Locking' and 'Pessimistic locking'. 'Optimistic Locking' assumes that a database transaction conflict is very rare to happen and such locked records can still be read (Shared lock). It uses a version number of the record to track the changes. This can be used by adding a lock_version column to the table and then is handled automatically by Rails.
Whereas 'Pessimistic locking' assumes that database transaction conflict is very likely to happen. It locks the record until the transaction is done (Exclusive lock). This can be done with ActiveRecord::Base#lock! or ActiveRecord::Locking::Pessimistic#with_lock.

a decent spreadsheet writer gem for ruby, https://github.com/felixbuenemann/xlsxtream, ran some rough benchmarks, and this one is the fastest and lowest memory consuming gem. although not feature complete.

This is a good read about common Rails errors which rollbar has captured https://rollbar.com/blog/top-10-ruby-on-rails-errors/

http://api.rubyonrails.org/v5.0/classes/ActiveRecord/QueryMethods.html#method-i-left_joins since rails 5

row caching and stream: true option for mysql2 https://github.com/brianmario/mysql2#row-caching

there are command-line options which you can add to bash scripts, can be added in the header like #!/bin/bash -e

set -x is very useful while writing shell scripts. It echos commands being run (even in for loops) which helps in debugging. Put this at the top of script file, and see the magic!

http://jsnice.org/ not a TIL, but lost and found it only today. This is a reverse tool that can be run on minified JS to get some more human readable ouput

You can scope relations like has_many, has_one and belongs_to. Eg: has_one :policy, -> { where active: true }