34

I have two versions of ruby gem. 

json (default: 2.0.2, 1.8.6)

Here, the latest version is set to default; however I need json 1.8.6 to be set as default. Is there anyway to make the older versions of the gem as default? cos I am unable to uninstall the default json version. Need a switch between available gem versions.

Prashanth Sams
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  • Do you use **rvm** to manage your ruby versions? – Ed de Almeida Mar 02 '17 at 07:48
  • @EddeAlmeida Yea I use RVM; anyway through it? – Prashanth Sams Mar 02 '17 at 08:12
  • Sure. You may create a private bundle for this application and install only the gem you need in this bundle. – Ed de Almeida Mar 02 '17 at 09:58
  • What version of Ruby are you using for this project? – Ed de Almeida Mar 02 '17 at 10:00
  • Then I am editing my answer accordingly. Have you tested it? – Ed de Almeida Mar 02 '17 at 13:02
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    Use bundler for your projects. – Sergio Tulentsev Mar 02 '17 at 13:07
  • https://stackoverflow.com/users/125816/sergio-tulentsev is correct. Using bundler will allow you to constrain the specific versions of gems to those in your Gemfile.lock. To focus your project on the earlier version, put "gem 'json', '~>1.8.6'" in your Gemfile and run "bundle". Run your server with "bundle exec rails s" and you're good to go. If you're using rvm or rbenv (with gemsets) you can create an application-specific gem cache, which will help to alleviate this issue by separating the available gems (per project, say) – k00ka Mar 19 '21 at 14:35

7 Answers7

14

Check what you have with:

gem list json

Set the one you want:

gem install --default -v1.8.6 json

This is most useful for things like "bundler"!!! For other things, using bundler and a Gemfile is probably a better choice.

mcr
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    Using `--default` will probably mess up your gem installation, and does not work for selecting a default lower version (I spent some time to fix my ruby installation after I run `gem install --default`) – acecilia Apr 05 '20 at 19:12
  • @acecilia how did you fixed it? – Alexandra Espichán Jun 30 '20 at 15:46
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    I uninstalled all gems and ruby, and then I reinstalled it – acecilia Jul 01 '20 at 20:34
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    `--default` makes it so the gem cannot be removed (*easily*). See the "Default gem" explanation here: https://stdgems.org/. I don't think the `--default` option is what you want here. See this answer https://stackoverflow.com/a/46691098/6824752 on how to delete a gem that you installed with `--default`. – Filip Kilibarda Oct 09 '20 at 20:37
4

Add 

gem 'json', '1.8.6'

to your Gemfile or execute 

gem install 'json' -v 1.8.6 # may require sudo if you use system ruby

from terminal.

marmeladze
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1

A Gemfile is a must but is not enough. You should also change the line

require 'json'

to

require 'bundler/setup'
Bundler.require :default

This will require all the gems specified in your Gemfile that without a group.

Aetherus
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0

Add this your Gemfile 

gem 'json', '1.8.6'

Now run this in your command line

bundle update

This should set your version you require

Gurmukh Singh
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0

Since you are using RVM to manage your Ruby versions,as you told in the comments, there is an easy solution: creating a private bundle for this application and install only the version of the gem you need in this bundle.

This is how you may do it:

1) Enter the directory of your application;

2) Type the following command

rvm use ruby-2.4.0@your_app_name --ruby-version --create

(I am assuming you are using Ruby 2.4.0. If this is not your version, replace it accordingly in the command above, please.)

3) Install bundler gem

gem install bundler

4) Make sure your Gemfile declares the version of the gem you need. In this case it must have the line:

gem "json", "1.8.6"

5) Now run

bundle install

And you are done!

WARNING: This procedure will make sure the json gem will be version 1.8.6. But you may have problems with your bundle install if some other gem installed requires a newer version of json gem. In this case you'll have to solve this conflict some other way.

To learn more about different bundles for different applications, read this.

I hope this helps.

Ed de Almeida
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0

You can manually move the related .gemspec file from
lib\ruby\gems\3.2.0\specifications\default\
to
lib\ruby\gems\3.2.0\specifications\
to unmark the gem as default.

Inversion
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-4

Context:

Running a simple ruby test from CLI

ruby -I test test/controllers/api_controller_test.rb

error:

You have already activated json 2.0.2, but your Gemfile requires json 1.8.6. Since json is a default gem, you can either remove your dependency on it or try updating to a newer version of bundler that supports json as a default gem. (Gem::LoadError)

The workaround was simply running the test with bundle exec as follows:

bundle exec ruby -I test test/controllers/api_controller_test.rb

Dharman
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Joshua Jones
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