giannisp

After automatically updating Postgres to 10.0 via Homebrew, the pg_ctl start command didn't work.
The error was "The data directory was initialized by PostgreSQL version 9.6, which is not compatible with this version 10.0."

Database files have to be updated before starting the server, here are the steps that had to be followed:

# need to have both 9.6.x and latest 10.0 installed, and keep 10.0 as default
brew unlink postgresql
brew install [email protected]
brew unlink [email protected]
brew link postgresql

cdesch

Cheat Sheets are greate but they are not a substitute for learning the framework and reading the documentation as we most certainly have not covered every potential example here. Please refer to the Rails Command Line Docs for more information.

Command Line Generator Info

Reference

You can get all of this information on the command line.

rails generate with no generator name will output a list of all available generators and some information about global options. rails generate GENERATOR --help will list the options that can be passed to the specified generator.

seancdavis

# app/models/image.rb

class Image < ActiveRecord::Base
  has_many :taggings, :as => :taggable
  has_many :tags, :through => :taggings
end