ruby: code to install gem if missing

Question

is there some ruby code I can use to install a gem from a local file, if that gem is not installed?

i'm thinking it would look something like:

if !gem_installed("some gem name")
  system "gem install -l local_copy.gem"
end

i don't know if anything exists that lets me check for gems like this or not...

Possible duplicate of [Check for Ruby Gem availability](http://stackoverflow.com/questions/1032114/check-for-ruby-gem-availability) — Nic, Mar 31 '16 at 17:03

score 6 · Accepted Answer · edited May 23 '17 at 12:18

6

Checking availability is covered in this previous StackOverflow Quesiton

begin
  gem "somegem"
  # with requirements
  gem "somegem", ">=2.0"
rescue Gem::LoadError
  # not installed
end

or

matches = Gem.source_index.find_name(gem.name, gem.version_requirements)

As for the install, it looks like rails uses the system for gem install also

 puts %x(#{cmd})

edited May 23 '17 at 12:18

Community

1
1

answered Oct 27 '09 at 19:26

jrhicks

14,759
9
42
57

1

`GEM::LoadError` should be `Gem::LoadError` – Anna Apr 22 '13 at 16:51
1

You might want to use `Gem.clear_paths` after the system call to `gem install ...`, to actually load the gem. See http://stackoverflow.com/questions/9384756/after-installing-a-gem-within-a-script-how-do-i-load-the-gem – ejoubaud Jul 18 '13 at 01:03

score 0 · Answer 2 · answered Dec 13 '19 at 13:07

0

This is my way of doing this

['json','date','mail'].each { |req|
    begin
        gem req
    rescue Gem::LoadError
        puts " -> install gem " + req
        Gem.install(req)
        gem req
    end
    require req
}

answered Dec 13 '19 at 13:07

Xavius Pupuss

160
1
6

ruby: code to install gem if missing

2 Answers2

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