How to reinstall a gem using bundler - ruby

Question

I did a bundle show and get the complete path to a gem directory.
Unfortunately, I removed the directory using rm -r gem_path. Then my rails app isn't working anymore. If I try start server or start rails console it outputs the following error:
<class:Application>: uninitialized constant MyAPP::Application::Gem (NameError)
What should I do to have it back?
I tried bundle install or bundle update in hope of forcing the bundle to search the gem and install it back, but didn't work.
I also tried delete the Gemfile.lock and run bundle install. Nothing changed, same error.
The gem in question is Act as taggable on.

Answer 1

If using rbenv, this will let you completely uninstall and re-install a gem such as rmagick:
First: Try a simple uninstall/reinstall
gem uninstall rmagick
bundle install
If that doesn't work, you can remove all trace of the installed gem. Find your gem installation location:
bundle show rmagick
BUNDLE_DIR=$(dirname $(dirname $(bundle show rmagick)))
echo $BUNDLE_DIR
Your gem installation prefix will either be the default e.g. ~/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0 or something you set e.g. .vendor
Clear out the gem directory:
rm -rf $BUNDLE_DIR/gems/rmagick-*
Clear out the compiled gem cache:
rm $BUNDLE_DIR/cache/rmagick*.gem
Also clear out bundler's spec cache:
rm $BUNDLE_DIR/specifications/rmagick*gemspec
Then you can re-install:
bundle install

Answer 2

You can always use:
gem pristine acts-as-taggable-on
pristine - Restores installed gems to pristine condition from files located in the gem cache
If you just want to restore the gem for the current project you should run:
bundle exec gem pristine acts-as-taggable-on

Answer 3

First I did a gem q --L, the shortcut for gem query --local. It outputs me the all the local gems installed.
actionmailer (3.2.8, 3.2.6, 3.2.1, 3.1.0)
actionpack (3.2.8, 3.2.6, 3.2.1, 3.1.0)
activemodel (3.2.8, 3.2.6, 3.2.1, 3.1.0)
activerecord (3.2.8, 3.2.6, 3.2.1, 3.1.0)
activeresource (3.2.8, 3.2.6, 3.2.1, 3.1.0)
activesupport (3.2.8, 3.2.6, 3.2.1, 3.1.0)
acts-as-taggable-on (2.3.3)
...
And then, following DVG advice, I uninstalled the gem using its correct name gem uninstall acts-as-taggable-on and ran bundle install. After that I was able to rails c or rails s again without any problem.

Answer 4

From project directory in terminal
gem uninstall gem_name

Answer 5

If using RVM with gems in ~/.rvm/, this works if bundle is not re-installing a gem.
First, delete the gem source:
bundle show $GEM
rm -rf $PATH_TO_GEM
Clear out the compiled gem cache:
rm -rf ~/.rvm/gems/ruby-$RUBYVERSION[#$GEMSET]/cache/$GEM.gem
Also clear out bundler's spec cache:
rm -rf ~/.rvm/gems/ruby-$RUBYVERSION[#$GEMSET]/specifications/$GEM*gemspec
Then you can re-install:
bundle install

Answer 6

bundle exec gem uninstall <gem_name> - uninstalls gem from the bundle (the <app_root>/vendor/bundle/ruby/2.3.0/gems/ path). This is equivalent to the answer #ioquatix gave, but is the slightly more convenient solution that he was looking for.
gem uninstall <gem_name> - uninstalls gem only from the global gemset in the system

Answer 7

If you've installed into ./bundle/vendor or similar, you need to remove the gem first but explicitly specify the GEM_HOME, e.g.
GEM_HOME=./vendor/bundle/ruby/2.3.0/ gem uninstall rmagick
This is by far the simplest way to uninstall gems installed using bundler into a vendor directory. Ideally, there would be a command bundle uninstall or bundle reinstall, etc.
If your goal is to simply reinstall, the following command will help:
GEM_HOME=./vendor/bundle/ruby/2.3.0/ gem uninstall rmagick && sudo -u http bundle install
If you're like me and have several web-applications under a directory (e.g. /srv/http), the following does it in all directories:
cd /srv/http
for d in ./*/ ; do (cd "$d" && sudo -u http GEM_HOME=./vendor/bundle/ruby/2.4.0/ gem uninstall --force rmagick && sudo -u http bundle install); done

Answer 8

If you're trying to reinstall rake, gem pristine rake will fail with Skipped rake-10.X.X, it is a default gem and bundle won't install it either, because it can't uninstall it.
If you're using rvm, it seems the easiest was is simply to do a rvm reinstall 2.x.x. At least for me, rvm repair all also didn't help.
The same probably goes for all other default gems. I'll just list them here so that the desperate googlers find some help:
bigdecimal
drip
io-console
json
minitest
psych
rake
rbtree
rdoc
test-unit