Rolify gem (user.add_role :admin ArgumentError: Unknown key: :optional)
Maybe you tried to add a role using rolify, like below: $ user = User.find(1) $ user.add_role :admin Then you got an error like: ArgumentError: »
Undefined local variable or method 'rolify'
If you are using rolify gem maybe you added rolify to your Gemfile like this this: source 'https://rubygems.org' gem 'rolify', '~> 5.1. »
How to generate a model without creating a migration
For example, you have already created a migration for ProductCategory Then you type: $ rails generate model ProductCategory you will see something like: invoke active_record conflict »
Nokogiri: Failed to build gem native extension.
Maybe you try to setup a project: $ bundle install If you get this error trying to install nokogiri gem Installing nokogiri 1.6.8 with native »
Rails db migration, undefined method `to_sym', can't figure out syntax
Maybe you are trying to do a migration like this: class AddTestingMigratoToBlog < ActiveRecord::Migration def change change_table :testing do |t| t.change :name, limit: »