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Ruby Notes

Preamble - Text Editor

A big regret I have is not properly setting my text editor to use spaces for the various rails projects I worked on (╯°□°）╯︵ ┻━┻ ...that said, remember to set your text editor to use 2 two spaces instead of tabs, others will appreciate ❤️

Syntax Checking Ruby and erb files

To lint a ruby file for syntax errors, ie. kind of known as linting a ruby file

ruby -c /path/to/mr-fancy-42-file.rb

To syntax an embedded Ruby file, ie. an erb file commonly used with the rails templating engine

1. Install rails-erb-check

gem install rails-erb-check

To syntax a mr-fancy-42-template-file.html.erb

rails-erb-check mr-fancy-42-template-file.html.erb

Working with RubyGems

gem is an app for interfacing with ruby gems, ie. packaged ruby apps from RubyGems

To list locally installed gems on the system

gem list

Yet another way to show a list of locally installed gems

gem query --local

To install a gem

gem install rails

To update gems

gem update --system

To check a Gemfile for syntax errors as stated above

ruby -c Gemfile

To read documenation for a particular gem, ie. rails or sinatra

ri rails

To view documentation for installed RubyGems installed for paritcular version of Ruby installed on the sytem in a web browser

gem server

To print a list of all available versions of a ruby gem ie. downloadable version from rubygems.org

gem list [GEM_NAME] -ra

Rails Notes

• rails defaults to the system encoding which is UTF-8 the majority of the time.
• Generally it's a good idea to check and make sure databases have been created before trying to deploy a rails app.

rake db:create:all

To create a rails project without a test suite

rails new [project_name] -T

To delete a model

rails destroy model [model_name]

To run all the migrations for the DB

rake db:migrate

To show the status of the migrations, ie. whether they have been applied or not

rake db:migrate:status

To rollback one migration

rake db:rollback

To clear the contents of the DB

rake db:reset

Working with PostgreSQL

Installation

To install postgres suite of tools on Debian

apt-get install postgresql-client postgresql postgresql-contrib
sudo -u postgres psql
ALTER USER postgres PASSWORD 'mrFancyPantsPassword';

Then proceed to create a user role who can create, edit, and drop databases in psql.

CREATE USER [mrFancyPantsUser] WITH PASSWORD 'mrFancyPantsPassword';
ALTER USER [mr_fancy_pants_user] CREATEDB;

Definitions

• foreign key a table column whose values reference rows in another table
• index a data structure on a table to increase lookup speed
• schema the structure definition of a database, i.e. tables columns and indexes of DB

psql

To create a role within the database

CREATE USER [mrFancyPantsUser] WITH PASSWORD 'mrFancyPantsPassword';

To list all the postgres roles on the system

\du

To create a database

create database [mr_fancy_pants_database];

To allow an existing postgres user be able to create databases

ALTER USER [mr_fancy_pants_user] CREATEDB;

To allow an existing postgres user be able to drop databases

ALTER USER [mr_fancy_pants_user] SUPERUSER;

To create a Postgres database

createdb <database_name>

To create a Postgres database using the psql monitor

create database mr_fancy_pants;

To create a new DB user for postgres

sudo -u postgres createuser <user_name>
createuser --interactive

To set a database password for a user in Postgres database

su - postgres
psql
alter user <user_name> with password ‘my_secret_password’;

🚨 The preferred way to change a password for a database user

\password

To create a database w/ a user having all privileges on the DB.

su - postgres
psql
grant all privileges on database <database_name> to <userName>;
\q

To dump a postgres database to a .sql file

pg_dump <dbname> > <fileName.sql>

Need to be logged in as postgres user to make this happen.

To import a .sql file into a postgres database, see 🙈

To create a postgres DB user

sudo -u postgres createuser <userName>

Postgres troubleshooting

psql: FATAL: Peer authentication failed for user see 🙈

MySQL Notes

To show databases

mysql> show databases;

To create a database

mysql> create database <db_name>;

To delete a database

mysql> drop database <db_name>;

To create a username for the newly created DB

mysql> grant all privileges on <db_name>.* to ‘username’@ ‘localhost’ identified by ‘password’;

To show permissions for a MySQL user

mysql> show grants for ‘username’@ ‘localhost’;

To show the structure of a table

mysql> show fields from users;

MySQL socket location on a Debian system

/var/run/mysqld/mysqld.sock

Useful Links

• meetup RubyFTW
• YouTube rails to phoenix
• reddit rails
• rubytapas sreencasts 📹
• haml2erb convert haml to erb
• treehouse creating SEO friendly URLs
• running CLI commands from within Ruby
• rubular Ruby Regular Expression Editor

Documentation

• Official Ruby Documentation

marketplace platforms

• baserails.com marketplace tutorial

Deploy

• DigitalOcean deploying a rails app
• StackOverflow capistrano - prevent echoing of passwords