无法加载此类文件-mysql2 / 2.4 / mysql2（LoadError）

Question

I am new to Ruby On Rails. I have been trying to create a model called Book using rails generate model Book command but I am getting the following error message:

F:\Faizul\Noah-Data\Backup\Ruby\Rails App\library>rails generate model Book
C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/mysql2-0.4.10-x64-mingw32/lib/mysql2/mysql2.rb:2:in `require': cannot load such file -- mysql2/2.4/mysql2 (LoadError)
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/mysql2-0.4.10-x64-mingw32/lib/mysql2/mysql2.rb:2:in `<top (required)>'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/mysql2-0.4.10-x64-mingw32/lib/mysql2.rb:31:in `require'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/mysql2-0.4.10-x64-mingw32/lib/mysql2.rb:31:in `<top (required)>'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/bundler-1.16.1/lib/bundler/runtime.rb:81:in `require'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/bundler-1.16.1/lib/bundler/runtime.rb:81:in `block (2 levels) in require'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/bundler-1.16.1/lib/bundler/runtime.rb:76:in `each'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/bundler-1.16.1/lib/bundler/runtime.rb:76:in `block in require'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/bundler-1.16.1/lib/bundler/runtime.rb:65:in `each'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/bundler-1.16.1/lib/bundler/runtime.rb:65:in `require'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/bundler-1.16.1/lib/bundler.rb:114:in `require'
        from F:/Faizul/Noah-Data/Backup/Ruby/Rails App/library/config/application.rb:7:in `<top (required)>'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.1.4/lib/rails/command/actions.rb:15:in `require'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.1.4/lib/rails/command/actions.rb:15:in `require_application_and_environment!'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.1.4/lib/rails/commands/generate/generate_command.rb:19:in `perform'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/thor-0.20.0/lib/thor/command.rb:27:in `run'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/thor-0.20.0/lib/thor/invocation.rb:126:in `invoke_command'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/thor-0.20.0/lib/thor.rb:387:in `dispatch'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.1.4/lib/rails/command/base.rb:63:in `perform'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.1.4/lib/rails/command.rb:44:in `invoke'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/railties-5.1.4/lib/rails/commands.rb:16:in `<top (required)>'
        from bin/rails:4:in `require'
        from bin/rails:4:in `<main>'

Made the below actions to overcome the issue but failed though :(

• Uninstalled mysql2
• Installed mysql2 using gem install mysql2 command
• Added 'msql2' to my Gemfile
• Configured database.yml file as below:

 default: &default adapter: mysql2 pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %> timeout: 5000 development: adapter: mysql2 database: library_development username: root password: root host: localhost port: 3309 test: adapter: mysql2 database: library_test username: root password: root host: localhost port: 3309 production: adapter: mysql2 database: library_production username: root password: root host: localhost port: 3309 

Answer 1

Currently, There is no mysql2 binary for Ruby 2.4 for Windows available at this time.

Please see this github issue for more info https://github.com/brianmario/mysql2/issues/861

Hope this may help you.

Answer 2

compile your mysql comment worked for me https://github.com/brianmario/mysql2/issues/923#issuecomment-361346864

but be aware that at step #3 instead of

cd "C:\\Ruby24-x64\\bin\\ruby" extconf.rb --with-mysql-dir="C:\\Program Files\\MySQL\\MySQL Connector.C 6.1"

I did

"C:\\Ruby24-x64\\bin\\ruby" extconf.rb --with-mysql-dir="C:\\Program Files (x86)\\MySQL\\MySQL Connector.C 6.1"

no "cd" at the begging and my connector was in "C:\\Program Files (x86)" folder.

also at step #6 I was copying

C:\\Ruby24-x64\\lib\\ruby\\gems\\2.4.0\\gems\\mysql2-0.4.10-x64-mingw32\\ext\\mysql2\\mysql2.so

to newly created folder

C:\\Ruby24-x64\\lib\\ruby\\gems\\2.4.0\\gems\\mysql2-0.4.10-x64-mingw32\\lib\\mysql2\\2.4

compiling process was showing plenty warnings but eventually rake db:migrate started work for me, so should yours code

Answer 3

Please install Mysql server . Install below gems.

Libmysqlclient-dev Or Mysql-devl