寶石:: LoadError：添加'寶石「mysql'`您的Gemfile

Question

Gem::LoadError: Specified 'mysql' for database adapter, but the gem is not loaded. Add `gem 'mysql'` to your Gemfile. 

我已經收到此錯誤時，我遵循本指南： http://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html 和運行

$ cd activerecord 
$ bundle exec rake test_sqlite3 

搜索後左右有一點，我被告知我需要修改Gemfile並添加gem 'mysql'然後運行bundle install。但是，我無法在列表中看到mysql。

Resolving dependencies... 
Using rake (10.1.0) 
Using i18n (0.6.5) 
Using json (1.8.0) 
Using minitest (5.0.8) 
Using atomic (1.1.14) 
Using thread_safe (0.1.3) 
Using tzinfo (0.3.38) 
Using activesupport (4.1.0.beta) from source at . 
Using rack (1.5.2) 
Using rack-test (0.6.2) 
Using actionpack (4.1.0.beta) from source at . 
Using builder (3.1.4) 
Using activemodel (4.1.0.beta) from source at . 
Using erubis (2.7.0) 
Using actionview (4.1.0.beta) from source at . 
Using mime-types (1.25) 
Using polyglot (0.3.3) 
Using treetop (1.4.15) 
Using mail (2.5.4) 
Using actionmailer (4.1.0.beta) from source at . 
Using arel (4.0.0) 
Using activerecord (4.1.0.beta) from source at . 
Using bcrypt-ruby (3.1.2) 
Using benchmark-ips (1.2.0) 
Using bundler (1.3.5) 
Using coffee-script-source (1.6.3) 
Using execjs (2.0.2) 
Using coffee-script (2.2.0) 
Using thor (0.18.1) 
Using railties (4.1.0.beta) from source at . 
Using coffee-rails (4.0.0) 
Using columnize (0.3.6) 
Using dalli (2.6.4) 
Using debugger-linecache (1.2.0) 
Using debugger-ruby_core_source (1.2.3) 
Using debugger (1.6.2) 
Using hike (1.2.3) 
Using jquery-rails (2.2.2) 
Using mustache (0.99.4) 
Using mini_portile (0.5.1) 
Using nokogiri (1.6.0) 
Using kindlerb (0.1.1) 
Using metaclass (0.0.1) 
Using mocha (0.14.0) 
Using multi_json (1.8.1) 
Using racc (1.4.9) 
Using rack-cache (1.2) 
Using tilt (1.4.1) 
Using sprockets (2.10.0) 
Using sprockets-rails (2.0.0) 
Using rails (4.1.0.beta) from source at . 
Using rdoc (3.12.2) 
Using redcarpet (2.2.2) 
Using sdoc (0.3.20) 
Using sqlite3 (1.3.8) 
Using turbolinks (1.3.0) 
Using uglifier (2.2.1) 
Using w3c_validators (1.2) 
Using yajl-ruby (1.1.0) 
Your bundle is complete! 
Gems in the group db were not installed. 
Use `bundle show [gemname]` to see where a bundled gem is installed. 

的Gemfile

source 'https://rubygems.org' 

gem 'rails',  path: '/home/terence/rails' 
gem 'arel',  github: 'rails/arel' 

gem 'mysql', '~> 2.9.1' 
gem 'mysql2', '~> 0.3.13' 

# Use sqlite3 as the database for Active Record 
gem 'sqlite3' 

# Use edge version of sprockets-rails 
gem 'sprockets-rails', github: 'rails/sprockets-rails' 

# Use SCSS for stylesheets 
gem 'sass-rails', github: 'rails/sass-rails' 

# Use Uglifier as compressor for JavaScript assets 
gem 'uglifier', '>= 1.3.0' 

# Use CoffeeScript for .js.coffee assets and views 
gem 'coffee-rails', github: 'rails/coffee-rails' 

# See https://github.com/sstephenson/execjs#readme for more supported runtimes 
# gem 'therubyracer', platforms: :ruby 

# Use jquery as the JavaScript library 
gem 'jquery-rails' 

# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks 
gem 'turbolinks' 

# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder 
gem 'jbuilder', '~> 1.2' 

# Run `rails console` in the browser. Read more: https://github.com/rails/web-console 
gem 'web-console', group: :development 

group :doc do 
    # bundle exec rake doc:rails generates the API under doc/api. 
    gem 'sdoc', require: false 
end 

# Use ActiveModel has_secure_password 
# gem 'bcrypt-ruby', '~> 3.1.2' 

# Use unicorn as the app server 
# gem 'unicorn' 

# Use Capistrano for deployment 
# gem 'capistrano', group: :development 

# Use debugger 
# gem 'debugger', group: [:development, :test] 

但是，如果我跑gem list，我的輸出如下：

*** LOCAL GEMS *** 

actionmailer (4.0.0) 
actionpack (4.0.0) 
activemodel (4.0.0) 
activerecord (4.0.0) 
activerecord-deprecated_finders (1.0.3) 
activesupport (4.0.0) 
arel (4.0.0) 
atomic (1.1.14) 
bcrypt-ruby (3.1.2) 
benchmark-ips (1.2.0) 
builder (3.1.4) 
bundler (1.3.5) 
bundler-unload (1.0.2) 
celluloid (0.15.2) 
chunky_png (1.2.8) 
coderay (1.0.9) 
coffee-rails (4.0.0) 
coffee-script (2.2.0) 
coffee-script-source (1.6.3) 
columnize (0.3.6) 
compass (0.12.2) 
cyaml (0.0.45) 
dalli (2.6.4) 
debugger (1.6.2) 
debugger-linecache (1.2.0) 
debugger-ruby_core_source (1.2.3) 
em-websocket (0.5.0) 
erubis (2.7.0) 
eventmachine (1.0.3) 
execjs (2.0.2) 
executable-hooks (1.2.3) 
ffi (1.9.0) 
formatador (0.2.4) 
fssm (0.2.10) 
guard (2.0.3) 
guard-compass (1.0.0) 
guard-haml (1.1.0) 
guard-livereload (2.0.0) 
haml (4.0.3) 
hike (1.2.3) 
http_parser.rb (0.5.3) 
i18n (0.6.5) 
jbuilder (1.5.1) 
jquery-rails (3.0.4, 2.2.2) 
json (1.8.0) 
kindlerb (0.1.1) 
listen (2.0.1) 
lumberjack (1.0.4) 
mail (2.5.4) 
metaclass (0.0.1) 
method_source (0.8.2) 
mime-types (1.25) 
mini_portile (0.5.1) 
minitest (5.0.8, 4.7.5) 
mocha (0.14.0) 
multi_json (1.8.1) 
mustache (0.99.4) 
mysql (2.9.1) 
mysql2 (0.3.13) 
nokogiri (1.6.0) 
polyglot (0.3.3) 
pry (0.9.12.2) 
racc (1.4.9) 
rack (1.5.2) 
rack-cache (1.2) 
rack-test (0.6.2) 
rails (4.0.0) 
railties (4.0.0) 
rake (10.1.0) 
rb-fsevent (0.9.3) 
rb-inotify (0.9.2) 
rdoc (3.12.2) 
redcarpet (2.2.2) 
rubygems-bundler (1.3.4) 
rvm (1.11.3.8) 
sass (3.2.12) 
sass-rails (4.0.0) 
sdoc (0.3.20) 
slop (3.4.6) 
sprockets (2.10.0) 
sprockets-rails (2.0.0) 
sqlite3 (1.3.8) 
thor (0.18.1) 
thread_safe (0.1.3) 
tilt (1.4.1) 
timers (1.1.0) 
treetop (1.4.15) 
turbolinks (1.3.0) 
tzinfo (0.3.38, 0.3.37) 
uglifier (2.2.1) 
w3c_validators (1.2) 
web-console (1.0.3) 
yajl-ruby (1.1.0) 

的database.yml

# SQLite version 3.x 
# gem install sqlite3 
# 
# Ensure the SQLite 3 gem is defined in your Gemfile 
# gem 'sqlite3' 
development: 
    adapter: sqlite3 
    database: db/development.sqlite3 
    pool: 5 
    timeout: 5000 

# Warning: The database defined as "test" will be erased and 
# re-generated from your development database when you run "rake". 
# Do not set this db to the same as development or production. 
test: 
    adapter: sqlite3 
    database: db/test.sqlite3 
    pool: 5 
    timeout: 5000 

production: 
    adapter: sqlite3 
    database: db/production.sqlite3 
    pool: 5 
    timeout: 5000 

請幫忙嗎？

Answer 1

求助：這花了我一段時間才弄清楚，我責怪導遊的錯。無論如何，請確保您正在編輯正確的Gemfile，並在您更改的Gemfile的目錄中執行bundle install。當我跑

$ cd rails 
$ bundle exec rails new ~/my-test-app --dev 

，實際上創建了一個名爲my-test-app夾在我的主目錄（其中包含在Gemfile中），但我必須在我的rails目錄中運行$ bundle exec rake test_sqlite3（其中還包含一個Gemfile中）。在我的輸出

上面看，它說Gems in the group db were not installed.當我跑bundle install，並參照我Gemfile了未執行行，他們只是這麼恰巧是安裝mysql，mysql2和PostgreSQL寶石線。我糾正，像這樣的文件：

的Gemfile

# AR 
    gem 'sqlite3', '~> 1.3.6' 
    gem 'mysql', '~> 2.9.1' 
    gem 'mysql2', '~> 0.3.13' 
    gem 'pg', '~> 0.17.0' 

    group :db do 
# gem 'pg', '>= 0.11.0' 
# gem 'mysql', '>= 2.9.0' 
# gem 'mysql2', '>= 0.3.13' 
    end 

Answer 2

我發現了另一個原因這個錯誤。雖然我已經安裝了mysql2寶石，在我的模型我指定的字符串「MySQL的」以establish_connection：

establish_connection adapter: "mysql", database: "my_database" 

顯然，這應該是「mysql2」不是「MySQL的」。

Answer 3

我有同樣的問題。解決辦法是，我忘記了相應地調整Gemfile。因此，轉到您創建您的Rails應用程序的目錄，然後使用sudo vim Gemfile打開Gemfile。 根據您的需要，您必須添加或刪除某些寶石。 在我的情況下，我不得不用「mysql」交換db-gem「sqlite3」。 之後，保存文件:wq並再次運行rails generate [model/controller/view] <name>。

爲我完成了這項工作，希望它對你有些幫助！