For Rails 5+ Initial Definition: If you are defining your Post model table, you can set references, index and foreign_key in one line: t.references :author, index: true, foreign_key: { to_table: :users } Update Existing: If you are adding references to an existing table, you can do this: add_reference :posts, :author, foreign_key: { to_table: :users } … Read more
rake db:migrate:status (Rails 3 to 5) or rails db:migrate:status (Rails 5) will accomplish this. See this commit. up means the migration has been run. down means the migration has not been run.
Rails 5+ def change change_column_default( :table_name, :column_name, from: nil, to: false ) end Rails 3 and Rails 4 def up change_column_default( :table_name, :column_name, nil ) end def down change_column_default( :table_name, :column_name, false ) end
The timestamp helper is only available in the create_table block. You can add these columns by specifying the column types manually: class AddTimestampsToUser < ActiveRecord::Migration def change_table add_column :users, :created_at, :datetime, null: false add_column :users, :updated_at, :datetime, null: false end end While this does not have the same terse syntax as the add_timestamps method you … Read more
In Rails 5 the API became explicit regarding tables/views, collectively data sources. # Tables and views ActiveRecord::Base.connection.data_sources ActiveRecord::Base.connection.data_source_exists? ‘kittens’ # Tables ActiveRecord::Base.connection.tables ActiveRecord::Base.connection.table_exists? ‘kittens’ # Views ActiveRecord::Base.connection.views ActiveRecord::Base.connection.view_exists? ‘kittens’ In Rails 2, 3 & 4 the API is about tables. # Listing of all tables and views ActiveRecord::Base.connection.tables # Checks for existence of kittens table/view … Read more
Rails 4.x When you already have users and uploads tables and wish to add a new relationship between them. All you need to do is: just generate a migration using the following command: rails g migration AddUserToUploads user:references Which will create a migration file as: class AddUserToUploads < ActiveRecord::Migration def change add_reference :uploads, :user, index: … Read more
remove_column :table_name, :column_name For instance: remove_column :users, :hobby would remove the hobby Column from the users table.