Fix PendingMigrationError when checking out later chapter branches

[roryokane]

A reader should be able to start the tutorial from any chapter. But when I run the server and try to visit the site after checking out the branch chapter-2, I get an ActiveRecord::PendingMigrationError.

$ bundle exec rails server
=> Booting WEBrick
=> Rails 4.2.6 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2016-05-11 19:33:02] INFO  WEBrick 1.3.1
[2016-05-11 19:33:02] INFO  ruby 2.2.2 (2015-04-13) [x86_64-darwin13]
[2016-05-11 19:33:02] INFO  WEBrick::HTTPServer#start: pid=27452 port=3000


Started GET "/" for ::1 at 2016-05-11 19:33:08 -0400
  ActiveRecord::SchemaMigration Load (0.2ms)  SELECT "schema_migrations".* FROM "schema_migrations"

ActiveRecord::PendingMigrationError (

Migrations are pending. To resolve this issue, run:

    bin/rake db:migrate RAILS_ENV=development

):
  activerecord (4.2.6) lib/active_record/migration.rb:392:in `check_pending!'
  activerecord (4.2.6) lib/active_record/migration.rb:373:in `call'
  actionpack (4.2.6) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
  activesupport (4.2.6) lib/active_support/callbacks.rb:88:in `__run_callbacks__'
  activesupport (4.2.6) lib/active_support/callbacks.rb:778:in `_run_call_callbacks'
  activesupport (4.2.6) lib/active_support/callbacks.rb:81:in `run_callbacks'
  actionpack (4.2.6) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (4.2.6) lib/action_dispatch/middleware/reloader.rb:73:in `call'
  actionpack (4.2.6) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
  actionpack (4.2.6) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
  web-console (2.3.0) lib/web_console/middleware.rb:28:in `block in call'
  web-console (2.3.0) lib/web_console/middleware.rb:18:in `catch'
  web-console (2.3.0) lib/web_console/middleware.rb:18:in `call'
  actionpack (4.2.6) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  railties (4.2.6) lib/rails/rack/logger.rb:38:in `call_app'
  railties (4.2.6) lib/rails/rack/logger.rb:20:in `block in call'
  activesupport (4.2.6) lib/active_support/tagged_logging.rb:68:in `block in tagged'
  activesupport (4.2.6) lib/active_support/tagged_logging.rb:26:in `tagged'
  activesupport (4.2.6) lib/active_support/tagged_logging.rb:68:in `tagged'
  railties (4.2.6) lib/rails/rack/logger.rb:20:in `call'
  actionpack (4.2.6) lib/action_dispatch/middleware/request_id.rb:21:in `call'
  rack (1.6.4) lib/rack/methodoverride.rb:22:in `call'
  rack (1.6.4) lib/rack/runtime.rb:18:in `call'
  activesupport (4.2.6) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
  rack (1.6.4) lib/rack/lock.rb:17:in `call'
  actionpack (4.2.6) lib/action_dispatch/middleware/static.rb:120:in `call'
  rack (1.6.4) lib/rack/sendfile.rb:113:in `call'
  railties (4.2.6) lib/rails/engine.rb:518:in `call'
  railties (4.2.6) lib/rails/application.rb:165:in `call'
  rack (1.6.4) lib/rack/lock.rb:17:in `call'
  rack (1.6.4) lib/rack/content_length.rb:15:in `call'
  rack (1.6.4) lib/rack/handler/webrick.rb:88:in `service'
  /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/2.2.0/webrick/httpserver.rb:138:in `service'
  /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/2.2.0/webrick/httpserver.rb:94:in `run'
  /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/2.2.0/webrick/server.rb:294:in `block in start_thread'


  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/actionpack-4.2.6/lib/action_dispatch/middleware/templates/rescues/_source.erb (4.5ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/actionpack-4.2.6/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (3.3ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/actionpack-4.2.6/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.6ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/actionpack-4.2.6/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb within rescues/layout (155.1ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/web-console-2.3.0/lib/web_console/templates/_markup.html.erb (0.7ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/web-console-2.3.0/lib/web_console/templates/_inner_console_markup.html.erb within layouts/inlined_string (0.9ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/web-console-2.3.0/lib/web_console/templates/_prompt_box_markup.html.erb within layouts/inlined_string (0.5ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/web-console-2.3.0/lib/web_console/templates/style.css.erb within layouts/inlined_string (0.6ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/web-console-2.3.0/lib/web_console/templates/console.js.erb within layouts/javascript (142.4ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/web-console-2.3.0/lib/web_console/templates/main.js.erb within layouts/javascript (0.5ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/web-console-2.3.0/lib/web_console/templates/error_page.js.erb within layouts/javascript (0.7ms)
  Rendered /Users/roryokane/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/web-console-2.3.0/lib/web_console/templates/index.html.erb (333.8ms)

When I follow the tutorial myself from chapter 1, one migration is created, 20160511232535_create_todos.rb. Whereas in the chapter-2 branch, the migration is named 20160511171537_create_todos.rb`. This difference is probably the cause of the error.

It is still possible to follow later chapters of the tutorial by starting from chapter 1 and copying and pasting the commands and the code in each chapter until you get to the chapter you are interested in.

[catmando]

yeah its a really good point