I have both Rails 2.3.4 and Rails 3.0.0.beta installed on my local machine. I am using ActiveRecord in a stand alone ruby script and when I do require 'active_record' 3.0.0.beta is loaded. How can I force it to require 2.3.4 instead? (without uninstalling 3.0.0.beta)
This is covered in the RubyGems manual # http://docs.rubygems.org/read/chapter/4
do:
require 'rubygems'
gem 'activerecord', '= 2.3.4'
A little trick is require 'activerecord' when you want 2.3.5 and 'active_record' when you want 3.0.0.beta.
You have a warning when you using activerecord require but it's load only 2.3.5.
After if you want manage several gem in same computer, you can try rvm and gemset system. It's really great.
Related
I am developing a gem at the moment. Here's how the .gemspec looks like:
gem.add_dependency 'activerecord', '~> 4.2'
...
gem.add_development_dependency 'rails', '4.2.5'
...
and here's my Gemfile:
source 'https://rubygems.org'
gemspec
I am setting up my main file, lib/my_gem.rb like so:
module MyGem
module Lib
end
end
ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
Bundler.require
However, if I start bundle console from my gem's folder, the dependencies are not required:
$ bundle console
Resolving dependencies...
irb(main):001:0> Rails
NameError: uninitialized constant Rails
...
irb(main):002:0> ActiveRecord
NameError: uninitialized constant ActiveRecord
...
What am I doing wrong?
I believe dependencies included via the gemspec command in the Gemfile are not automatically required by Bundler.require. Only gems listed directly in the Gemfile itself are.
Additionally, gems included in only certain Bundler groups, like 'development', may not be required by a Bundle.require even if they were included directly in the Gemfile, you need to tell bundler to require groups other than default.
You can always require gems manually though, like require 'rails'. Bundle.require doesn't do anything but require gem for each gem in your Gemfile (or at least default group in your Gemfile), it's doing any magic other than looking up all the gems in your Gemfile and requiring them. Bundle.require is considered by some to be a bad practice anyway, you should just require the dependencies you need in the files you need them, some say. Although Rails doesn't agree, and Rails apps have their own somewhat complicated way of auto-loading things.
But if you are in a Rails app, as your example dependencies suggest... why are you doing any require 'bundler/setup' or Bundle.require yourself at all though, instead of letting Rails boot process take care of it? Rails boot process will take care of requiring the Bundler groups you probably expect too (like the "development" group when in Rails.env == 'development').
You can use the bundler api yourself directly like you're doing, it's not too hard. But Rails ordinarily takes care of this for you, and if you are using Rails, rails probably already has done a Bundler.setup and Bundler.require as part of Rails boot process.
I'm trying to use the barby gem that I installed, but when I do it gives me this error.
LoadError cannot load such file -- barby
Here's the require methods in my controller.
require 'barby'
require 'barby/barcode/ean_13'
require 'barby/outputter/ascii_outputter'
require 'barby/outputter/html_outputter'
class PalletsController < ApplicationController
-snip-
end
Here's the gem in my gemfile.
gem 'barby'
Any help would be greatly appreciated.
You only add require when you are dealing with a ruby project. In your case(ruby-on-rails), you can remove those lines.
Also, keep in mind that you should add your gems into your Gemfile
bundle install? It sounds like you do not have the gem installed when ruby tries to load it, it can not find it. Gem list will list out the installed gems on the system, or bundle exec gem list.
gem list
This is a really basic ruby gems question. I'm familiar with writing simple ruby scripts like this:
#!/usr/bin/ruby
require 'time'
t = Time.at(123)
puts t
Now I'd like to use my own ruby gem in my script. In my rails project I can simply require 'my_gem'. However this doesn't work in a stand-alone script. What's the best/proper way to use my own gem in a stand-alone ruby script?
You should be able to simply require it directly in recent versions of Ruby.
# optional, also allows you to specify version
gem 'chronic', '~>0.6'
# just require and use it
require 'chronic'
puts Chronic::VERSION # yields "0.6.7" for me
If you are still on Ruby 1.8 (which does not require RubyGems by default), you will have to explicitly put this line above your attempt to load the gem:
require 'rubygems'
Alternatively, you can invoke the Ruby interpreter with the flag -rubygems which will have the same effect.
See also:
http://docs.rubygems.org/read/chapter/3#page70
http://docs.rubygems.org/read/chapter/4
You could use something like this. It will install the gem if it's not already installed:
def load_gem(name, version=nil)
# needed if your ruby version is less than 1.9
require 'rubygems'
begin
gem name, version
rescue LoadError
version = "--version '#{version}'" unless version.nil?
system("gem install #{name} #{version}")
Gem.clear_paths
retry
end
require name
end
load_gem 'your_gem'
It is to be noted that bundler itself can deal with this. It's particularly interesting since bundler ships with Ruby by default since version 2.6, and you don't need to install it manually anymore.
The idea is:
to require bundler/inline at the top of your script,
to use the gemfile method, and declare the gems you need inside a block, like you'd do in a Gemfile,
after the end of this section, your gems are available!
For instance:
require 'bundler/inline'
gemfile do
source 'https://rubygems.org'
gem 'rainbow'
end
# From here on, rainbow is available so I can
# print colored text into my terminal
require 'rainbow'
puts Rainbow('This will be printed in red').red
The official documentation can be found on bundler website: bundler in a single file ruby script
Installing gems with something like the following should work. Be mindful of whether gems should be installed as part of system ruby or a user's.
#!/usr/bin/env ruby
require 'rubygems'
def install_gem(name, version=Gem::Requirement.default)
begin
gem name, version
rescue LoadError
print "ruby gem '#{name}' not found, " <<
"would you like to install it (y/N)? : "
answer = gets
if answer[0].downcase.include? "y"
Gem.install name, version
else
exit(1)
end
end
end
# any of the following will work...
install_gem 'activesupport'
install_gem 'activesupport', '= 4.2.5'
install_gem 'activesupport', '~> 4.2.5'
# require as normal (since not all gems install & require with same name) ...
require 'active_support/all'
...
I'm not sure if I understood your question right, but perhaps you don't have a gem, even if you write it (you are a beginner, so perhaps you misunderstood the concept of gems).
Just to be sure: You have a gemspec for your gem? If not, then you have no gem, but a single script.
When you want your own script inside another script, you may just do:
require 'my_script'
With ruby 1.8 this works fine, if my_script.rb is in the same folder as your main script. With ruby 1.9+ you can use:
require_relative 'my_script'
There is no need of a gem in this case.
The following ought to work as a script, with ActiveRecord 3.1 (note that this is without Rails, not the other way around):
#!/usr/bin/env ruby
require "rubygems"
require "active_record"
dbconfig = YAML::load(File.open('database.yml'))
ActiveRecord::Base.establish_connection(dbconfig)
irb
Unfortunately, it gives the error:
... connection_specification.rb:71:in `rescue in establish_connection': ...
Please install the mysql2 adapter: `gem install activerecord-mysql2-adapter` ...
Adding the line gem 'mysql2', '<0.3' before require "active_record" as suggested by some previous posts (which reference 0.2.7, the 0.2 gem at the time; presently it's 0.2.18) doesn't change it.
How can I get it to work? I want ActiveRecord but not the whole of Rails.
Run in terminal
gem install mysql2
and add row to you code require 'mysql2'
#!/usr/bin/env ruby
require "rubygems"
require 'mysql2'
require "active_record"
dbconfig = YAML::load(File.open('database.yml'))
ActiveRecord::Base.establish_connection(dbconfig)
This has fixed my issue, at least temporarily. I haven't yet restarted, so I don't know if it'll survive that. And it seems like a dirty hack; there's got to be a better way.
I haven't yet tested Aleksei's answer above, since I'm not having the same issue after having run this command. Will update ifwhen I do.
sudo install_name_tool -change libmysqlclient.18.dylib /usr/local/mysql/lib/libmysqlclient.18.dylib ~/.rvm/gems/`rvm current`/gems/mysql2-0.3.11/lib/mysql2/mysql2.bundle
require 'rubygems'
require 'mechanize'
agent = Mechanize.new
page = agent.get("http://google.com/")
This simple script works ok.
But if I'am trying to add
require 'rubygems' and require 'mechanize' to the Rails controller, server gives:
LoadError in NewsController#find
no such file to load -- mechanize
I use RVM on Ubuntu 10.04 server machnine. Ruby version: 1.9.2, Rails version: 3.0.3.
Server: Passanger under Apache2.
P.S. If I run rails server and go to mysite.com:3000 all works without any error, so there is a problem with Passanger!
Please, help me!
You shouldn't require gems in your controller. Thats why Bundler was added to Rails 3.
Just add mechanize to your Gemfile like this
gem "mechanize"
and run
bundle install
on the command line.
Any gem mentioned here will be required on application startup.
The way you manage dependencies in Rails 3, is using the Gemfile and Bundler.
Edit your Gemfile and add
gem "mechanize"
Then run
$ bundle install
Restart the server. The library will automatically be loaded. No need to manually require RubyGems.