New to SQL / Ruby on Rails - database created, schema dumb error - ruby-on-rails

I'm working on teaching myself both SQL & Ruby on Rails, and just starting out. I'm following a tutorial and successfully created a new SQL database and user, as well as a project.
The next step was to run a schema dump (even though the database is empty at the moment) just to confirm that the project could talk to the new database. Unfortunately it is a no go. I can see the database listed in my config/database.yml, and it contains the proper references to both the user and the database, but for some reason the schema dump fails.
Below are my commands, followed by the error, followed by the command again with a trace. I really appreciate any help you can offer.
C:\Users\Danny\Documents\Sites\demo_project>rails db:schema:dump
rails aborted!
LoadError: cannot load such file -- mysql2/2.4/mysql2
C:/Users/Danny/Documents/Sites/demo_project/config/application.rb:7:in `<top (required)>'
C:/Users/Danny/Documents/Sites/demo_project/Rakefile:4:in `require_relative'
C:/Users/Danny/Documents/Sites/demo_project/Rakefile:4:in `<top (required)>'
bin/rails:4:in `require'
bin/rails:4:in `<main>'
(See full trace by running task with --trace)
C:\Users\Danny\Documents\Sites\demo_project>rails db:schema:dump --trace
rails aborted!
LoadError: cannot load such file -- mysql2/2.4/mysql2
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/mysql2-0.4.10-x64-mingw32/lib/mysql2/mysql2.rb:2:in `require'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/mysql2-0.4.10-x64-mingw32/lib/mysql2/mysql2.rb:2:in `<top (required)>'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/mysql2-0.4.10-x64-mingw32/lib/mysql2.rb:31:in `require'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/mysql2-0.4.10-x64-mingw32/lib/mysql2.rb:31:in `<top (required)>'
C:/Ruby24-x64/lib/ruby/site_ruby/2.4.0/bundler/runtime.rb:81:in `require'
C:/Ruby24-x64/lib/ruby/site_ruby/2.4.0/bundler/runtime.rb:81:in `block (2 levels) in require'
C:/Ruby24-x64/lib/ruby/site_ruby/2.4.0/bundler/runtime.rb:76:in `each'
C:/Ruby24-x64/lib/ruby/site_ruby/2.4.0/bundler/runtime.rb:76:in `block in require'
C:/Ruby24-x64/lib/ruby/site_ruby/2.4.0/bundler/runtime.rb:65:in `each'
C:/Ruby24-x64/lib/ruby/site_ruby/2.4.0/bundler/runtime.rb:65:in `require'
C:/Ruby24-x64/lib/ruby/site_ruby/2.4.0/bundler.rb:114:in `require'
C:/Users/Danny/Documents/Sites/demo_project/config/application.rb:7:in `<top (required)>'
C:/Users/Danny/Documents/Sites/demo_project/Rakefile:4:in `require_relative'
C:/Users/Danny/Documents/Sites/demo_project/Rakefile:4:in `<top (required)>'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/rake-12.3.1/lib/rake/rake_module.rb:29:in `load'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/rake-12.3.1/lib/rake/rake_module.rb:29:in `load_rakefile'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/rake-12.3.1/lib/rake/application.rb:703:in `raw_load_rakefile'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/rake-12.3.1/lib/rake/application.rb:104:in `block in load_rakefile'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/rake-12.3.1/lib/rake/application.rb:186:in `standard_exception_handling'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/rake-12.3.1/lib/rake/application.rb:103:in `load_rakefile'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands/rake_proxy.rb:13:in `block in run_rake_task'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/rake-12.3.1/lib/rake/application.rb:186:in `standard_exception_handling'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands/rake_proxy.rb:11:in `run_rake_task'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands/commands_tasks.rb:51:in `run_command!'
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands.rb:18:in `<top (required)>'
bin/rails:4:in `require'
bin/rails:4:in `<main>'

In the below mentioned command you need compile yourself
C:\Users\xxxx\xxxx>gem install mysql2 --platform=ruby -- '--with-mysql-lib="I:\mysql-5.7.19-winx64\lib" --with-mysql-include="I:\mysql-5.7.19-winx64\include"'
If you still got the error then you might need to downgrade to 2.3 for mysql support.
For the mysql compatibility for rails on windows..please find below the github link:
https://github.com/brianmario/mysql2/issues/861

Related

Cannot run migrations on Rails

I believe I have an environment setup issue here, which I cannot seem to figure out. Trying to generate a migration in order to set up my Users table, but keep receiving the following message.
gem pristine --all
Sunnys-MBP:Vine SunnyPatel$ rails generate migration Users
/Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/msgpack-1.3.1/lib/msgpack.rb:11:in `require': incompatible library version - /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/msgpack-1.3.1/lib/msgpack/msgpack.bundle (LoadError)
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/msgpack-1.3.1/lib/msgpack.rb:11:in `rescue in <top (required)>'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/msgpack-1.3.1/lib/msgpack.rb:8:in `<top (required)>'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/store.rb:3:in `require'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/store.rb:3:in `block in <top (required)>'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/explicit_require.rb:43:in `rescue in with_gems'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/explicit_require.rb:39:in `with_gems'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/store.rb:3:in `<top (required)>'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache.rb:74:in `require_relative'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache.rb:74:in `<top (required)>'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap.rb:3:in `require_relative'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap.rb:3:in `<top (required)>'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/setup.rb:1:in `require_relative'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/bootsnap-1.4.5/lib/bootsnap/setup.rb:1:in `<top (required)>'
from /Users/SunnyPatel/Desktop/Vine/config/boot.rb:4:in `require'
from /Users/SunnyPatel/Desktop/Vine/config/boot.rb:4:in `<top (required)>'
from /Users/SunnyPatel/Desktop/Vine/config/application.rb:1:in `require_relative'
from /Users/SunnyPatel/Desktop/Vine/config/application.rb:1:in `<top (required)>'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/spring-2.1.0/lib/spring/application.rb:92:in `require'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/spring-2.1.0/lib/spring/application.rb:92:in `preload'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/spring-2.1.0/lib/spring/application.rb:157:in `serve'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/spring-2.1.0/lib/spring/application.rb:145:in `block in run'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/spring-2.1.0/lib/spring/application.rb:139:in `loop'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/spring-2.1.0/lib/spring/application.rb:139:in `run'
from /Users/SunnyPatel/.rvm/gems/ruby-2.5.1/gems/spring-2.1.0/lib/spring/application/boot.rb:19:in `<top (required)>'
from /Users/SunnyPatel/.rbenv/versions/2.5.1/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
from /Users/SunnyPatel/.rbenv/versions/2.5.1/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
from -e:1:in `<main>'
This is likely due to the fact that the system version of ruby is different to the version for your application.
Try appending bundle exec to your command.
bundle exec rails generate migration Users
Also, it's not likely that your command will work. You want to create a new User model? Then you want this command instead:
bundle exec rails generate model User

rake db:schema:dump not working

I'm learning ruby on rails on windows platform in windows 8. Now I'm in the database part where rake db:schema:dump command should create a file in config folder named schema.rb, but that's not happening. When I'm typing rake db:schema:dump it shows rake aborted and a long list. Please help.
Here is what shows up in console:
C:\Users\New User\sites2\learning_rails>rake db:schema;dump
rake aborted!
Bundler::GemRequireError: There was an error while trying to load the gem 'uglif
ier'.
Gem Load Error is: Could not find a JavaScript runtime. See https://github.com/r
ails/execjs for a list of available runtimes.
Backtrace for gem load error is:
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/execjs-2.7.0/lib/execjs/runtimes.rb:58:in
`autodetect'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/execjs-2.7.0/lib/execjs.rb:5:in `<module:
ExecJS>'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/execjs-2.7.0/lib/execjs.rb:4:in `<top (re
quired)>'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/uglifier-3.0.0/lib/uglifier.rb:5:in `requ
ire'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/uglifier-3.0.0/lib/uglifier.rb:5:in `<top
(required)>'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.12.5/lib/bundler/runtime.rb:86:
in `require'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.12.5/lib/bundler/runtime.rb:86:
in `block (2 levels) in require'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.12.5/lib/bundler/runtime.rb:81:
in `each'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.12.5/lib/bundler/runtime.rb:81:
in `block in require'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.12.5/lib/bundler/runtime.rb:70:
in `each'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.12.5/lib/bundler/runtime.rb:70:
in `require'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.12.5/lib/bundler.rb:102:in `req
uire'
C:/Users/New User/sites2/learning_rails/config/application.rb:7:in `<top (requir
ed)>'
C:/Ruby22-x64/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55:in
`require'
C:/Ruby22-x64/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55:in
`require'
C:/Users/New User/sites2/learning_rails/Rakefile:4:in `<top (required)>'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/rake_module.rb:28:in
`load'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/rake_module.rb:28:in
`load_rakefile'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/application.rb:689:i
n `raw_load_rakefile'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/application.rb:94:in
`block in load_rakefile'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/application.rb:176:i
n `standard_exception_handling'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/application.rb:93:in
`load_rakefile'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/application.rb:77:in
`block in run'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/application.rb:176:i
n `standard_exception_handling'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/lib/rake/application.rb:75:in
`run'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/rake-11.1.2/bin/rake:33:in `<top (require
d)>'
C:/Ruby22-x64/bin/rake:22:in `load'
C:/Ruby22-x64/bin/rake:22:in `<main>'
Bundler Error Backtrace:
C:/Users/New User/sites2/learning_rails/config/application.rb:7:in `<top (requir
ed)>'
C:/Users/New User/sites2/learning_rails/Rakefile:4:in `<top (required)>'
ExecJS::RuntimeUnavailable: Could not find a JavaScript runtime. See https://git
hub.com/rails/execjs for a list of available runtimes.
C:/Users/New User/sites2/learning_rails/config/application.rb:7:in `<top (requir
ed)>'
C:/Users/New User/sites2/learning_rails/Rakefile:4:in `<top (required)>'
(See full trace by running task with --trace)
install nodejs
Uglifier is JavaScript compressor, so it need javascript runtime try installing nodejs
apt-get install nodejs
or
brew install nodejs
if you are on a OSX.

Running RoR on Fedora, get: undefined local variable or method `ext_dir' for

I'm trying to install Catarse.me on a Fedora 19 machine, ready to be pushed to Heroku.
I've managed to successfully run bundle install. But when I try
rake db:migrate
I receive this error
[root#acer]$ rake db:migrate
rake aborted!
undefined local variable or method `ext_dir' for #<Gem::Specification:0x450c8ce RedCloth-4.2.9>
/home/user/rails/catarse/config/boot.rb:7:in `<top (required)>'
/home/user/rails/catarse/config/application.rb:1:in `<top (required)>'
/home/user/rails/catarse/Rakefile:4:in `<top (required)>'
(See full trace by running task with --trace)
I've individually checked each of these files, and on the lines noted there's a call to
variablename = File.expand_path('../path/to/Gemfile', __FILE__)
CORRECTION The stack trace points to line 7 in book.rb
Bundler.setup
I've googled but the only relevant hit is this StackOverflow question but whose situation and answer is unrelated to my problem.
I'd appreciate the help.
Running rake db:migrate -- trace gives
rake aborted!
undefined local variable or method `ext_dir' for #<Gem::Specification:0x4700158 RedCloth-4.2.9>
/usr/local/share/ruby/site_ruby/rubygems/specification.rb:1887:in `method_missing'
/usr/share/gems/gems/bundler-1.3.1/lib/bundler/rubygems_ext.rb:42:in `load_paths'
/usr/share/gems/gems/bundler-1.3.1/lib/bundler/runtime.rb:37:in `block in setup'
/usr/share/gems/gems/bundler-1.3.1/lib/bundler/runtime.rb:19:in `setup'
/usr/share/gems/gems/bundler-1.3.1/lib/bundler.rb:120:in `setup'
/home/mei/rails/catarse/config/boot.rb:7:in `<top (required)>'
/usr/local/share/ruby/site_ruby/rubygems/core_ext/kernel_require.rb:55:in `require'
/usr/local/share/ruby/site_ruby/rubygems/core_ext/kernel_require.rb:55:in `require'
/home/mei/rails/catarse/config/application.rb:1:in `<top (required)>'
/usr/local/share/ruby/site_ruby/rubygems/core_ext/kernel_require.rb:55:in `require'
/usr/local/share/ruby/site_ruby/rubygems/core_ext/kernel_require.rb:55:in `require'
/home/mei/rails/catarse/Rakefile:4:in `<top (required)>'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/rake_module.rb:25:in `load'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/rake_module.rb:25:in `load_rakefile'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/application.rb:637:in `raw_load_rakefile'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/application.rb:94:in `block in load_rakefile'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/application.rb:93:in `load_rakefile'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/application.rb:77:in `block in run'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling'
/usr/local/share/gems/gems/rake-10.1.0/lib/rake/application.rb:75:in `run'
/usr/local/share/gems/gems/rake-10.1.0/bin/rake:33:in `<top (required)>'
/bin/rake:23:in `load'
/bin/rake:23:in `<main>'
By your trace, it seems like it's a bundler issue,
running
gem update bundler
should fix it.

rake command gets "cannot load such file -- yaml/encoding"

I want to use ruby-1.9.3-p194 on CentOS 5.8. I could install it with rvm and also system (libyaml and libyaml-devel were installed). But I can't run all of 'rake' tasks (not only 'rake spec').
I got "cannot load such file -- yaml/encoding". It's a sample result with trace. The 'rake' version is '0.9.2.2'. How can I resolve it?
$ rake spec --trace
rake aborted!
cannot load such file -- yaml/encoding
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:182:in `require'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:182:in `block in require'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:547:in `new_constants_in'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:182:in `require'
/home/inohiro/Projects/rails_2_3_14_r5066/src/admin/lib/tasks/fixture_dump.rake:2:in `<top (required)>'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:171:in `load'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:171:in `block in load_with_new_constant_marking'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:547:in `new_constants_in'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/dependencies.rb:171:in `load_with_new_constant_marking'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rails-2.3.14/lib/tasks/rails.rb:14:in `block in <top (required)>'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rails-2.3.14/lib/tasks/rails.rb:14:in `each'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rails-2.3.14/lib/tasks/rails.rb:14:in `<top (required)>'
/home/inohiro/Projects/rails_2_3_14_r5066/src/admin/Rakefile:10:in `require'
/home/inohiro/Projects/rails_2_3_14_r5066/src/admin/Rakefile:10:in `<top (required)>'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load_rakefile'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/application.rb:501:in `raw_load_rakefile'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/application.rb:82:in `block in load_rakefile'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/application.rb:81:in `load_rakefile'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/application.rb:65:in `block in run'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/gems/rake-0.9.2.2/bin/rake:33:in `<top (required)>'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/bin/rake:19:in `load'
/home/inohiro/.rvm/gems/ruby-1.9.3-p194/bin/rake:19:in `<main>'
It's not a rake problem, it's a ruby <=> rails version incompatibility. You're using the most recent stable version of ruby with the rails version from the era of dinosaurs.
You need to do some hacking in order for them to understand each other!
Here's a nice read that should get you started:
http://scottiestech.info/2012/02/07/make-rails-2-3-x-happy-with-ruby-1-9-3/
This gist also rocks:
https://gist.github.com/1976864 (thanks Jonathan!)

something wrong with my rails app deploy to heroku

I do my deploy as the heroku guide.
But when I use commend 'heroku rake db:migrate', then present these errors:
Running rake db:migrate attached to terminal... up, run.1
(in /app)
rake aborted!
no such file to load -- test/unit/error
<internal:lib/rubygems/custom_require>:29:in `require'
<internal:lib/rubygems/custom_require>:29:in `require'
/app/.gems/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:in `block in require'
/app/.gems/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:521:in `new_constants_in'
/app/.gems/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:in `require'
/app/.gems/gems/activesupport-2.2.2/lib/active_support/deprecation.rb:224:in `<top (required)>'
<internal:lib/rubygems/custom_require>:29:in `require'
<internal:lib/rubygems/custom_require>:29:in `require'
/app/.gems/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:in `block in require'
/app/.gems/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:521:in `new_constants_in'
/app/.gems/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:in `require'
/app/.gems/gems/activesupport-2.2.2/lib/active_support.rb:37:in `<top (required)>'
<internal:lib/rubygems/custom_require>:29:in `require'
<internal:lib/rubygems/custom_require>:29:in `require'
/app/.gems/gems/rails-2.2.2/lib/tasks/misc.rake:11:in `<top (required)>'
/app/.gems/gems/rails-2.2.2/lib/tasks/rails.rb:4:in `load'
/app/.gems/gems/rails-2.2.2/lib/tasks/rails.rb:4:in `block in <top (required)>'
/app/.gems/gems/rails-2.2.2/lib/tasks/rails.rb:4:in `each'
/app/.gems/gems/rails-2.2.2/lib/tasks/rails.rb:4:in `<top (required)>'
<internal:lib/rubygems/custom_require>:29:in `require'
<internal:lib/rubygems/custom_require>:29:in `require'
/app/Rakefile:10:in `<top (required)>'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2373:in `load'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2373:in `raw_load_rakefile'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2007:in `block in load_rakefile'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2058:in `standard_exception_handling'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2006:in `load_rakefile'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:1991:in `run'
/usr/ruby1.9.2/bin/rake:31:in `<main>'
jason#jason-VirtualBox:~/work/depot$ rake db:migrate
(in /home/jason/work/depot)
I visit my app in heroku, it presents the error:
Application Error
An error occurred in the application and your page could not be served. Please try again in a few moments.
If you are the application owner, check your logs for details.
Try adding pg gem in gem file for the production environment and execute the below command
$ bundle install --without production
Since Heroku uses Postgresql databases we must use this way. Hope helps you.

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