我在尝试mysql2为Rails 安装gem 时遇到了一些问题.当我尝试通过运行安装它bundle install或gem install mysql2它给我以下错误:
安装mysql2时出错:错误:无法构建gem原生扩展.
我该如何修复并成功安装mysql2？
在我的gemfile中我有:
gem 'mysql2'
我的database.yml如下:
default: &default
adapter: mysql2
database: <%= ENV['db_name'] %>
username: <%= ENV['db_user'] %>
password: <%= ENV['db_pass'] %>
host: <%= ENV['db_host'] %>
pool: 32
socket: <%= ENV['socket'] %>
development:
<<: *default
production:
<<: *default
我已经运行了两个bundle update并且bundle install我的Gemfile.lock显示了mysql2.
但是,当我运行时,我rake db:migrate在我的计算机和登台服务器上都得到了这个:
myproject.com(master)$ rake db:migrate
WARNING: Use strings for Figaro configuration. 10000012508 was converted to "10000012508".
WARNING: Use strings for Figaro configuration. 860526407370038 was converted to "860526407370038".
rake aborted!
Gem::LoadError: Specified 'mysql2' for database adapter, …ruby-on-rails mysql2 ruby-on-rails-4 ruby-on-rails-4.1 ruby-on-rails-4.2
Gem::LoadError
Specified 'mysql2' for database adapter, but the gem is not loaded.
Add `gem 'mysql2'` to your Gemfile
加载以下文件时发生此错误:
active_record/base
这是我在运行rails服务器时遇到的错误.
The mysql2 gem has been added to the Gemfile as well.
我已经完成了bundle install,并尝试重新启动服务器,但仍然得到错误.
我有3个型号:
class Student < ActiveRecord::Base
has_many :student_enrollments, dependent: :destroy
has_many :courses, through: :student_enrollments
end
class Course < ActiveRecord::Base
has_many :student_enrollments, dependent: :destroy
has_many :students, through: :student_enrollments
end
class StudentEnrollment < ActiveRecord::Base
belongs_to :student
belongs_to :course
end
我希望查询Courses表中的课程列表,这些课程在StudentEnrollments表中与特定学生相关联.
我发现也许Left Join是要走的路,但似乎rails中的join()只接受一个表作为参数.我认为可以做我想要的SQL查询是:
SELECT *
FROM Courses c LEFT JOIN StudentEnrollment se ON c.id = se.course_id
WHERE se.id IS NULL AND se.student_id = <SOME_STUDENT_ID_VALUE> and c.active = true
如何以Rails 4方式执行此查询？
任何输入都表示赞赏.
当我尝试安装mysql2 gem时,它失败并没有明显的错误.有谁知道如何解决这个问题,所以mysql2安装？
$ sudo gem install mysql2
Building native extensions. This could take a while...
ERROR: Error installing mysql2:
ERROR: Failed to build gem native extension.
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
checking for rb_thread_blocking_region()... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... no …当尝试通过我的rails应用程序连接到mysql服务器时,我收到以下错误
D:/Program_Files/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require':
Incorrect MySQL client library version! This gem was compiled for 6.0.0 but the client library is 5.0.27. (RuntimeError)
我怎样才能纠正它？
我试图安装一个使用mysql2gem的开源rails 3.2.21应用程序,但是当我尝试运行bundlecommant时,我收到以下错误:
Fetching: mysql2-0.3.18.gem (100%)
Building native extensions. This could take a while...
p
ERROR: Error installing mysql2:
ERROR: Failed to build gem native extension.
/Users/my_username/.rvm/rubies/ruby-2.1.2/bin/ruby -r ./siteconf20150614-72129-orqsb7.rb extconf.rb
checking for ruby/thread.h... yes
checking for rb_thread_call_without_gvl() in ruby/thread.h... yes
checking for rb_thread_blocking_region()... yes
checking for rb_wait_for_single_fd()... yes
checking for rb_hash_dup()... yes
checking for rb_intern3()... yes
-----
Using mysql_config at /usr/local/bin/mysql_config
-----
checking for mysql.h... yes
checking for errmsg.h... yes
checking for mysqld_error.h... yes
-----
Don't know …我正在尝试使用Rails 3.2.3安装mysql2 gem并且它失败了:
? bundle install
Fetching gem metadata from https://rubygems.org/.........
Using rake (0.9.2.2)
Using i18n (0.6.0)
Using multi_json (1.2.0)
Using activesupport (3.2.3)
Using builder (3.0.0)
Using activemodel (3.2.3)
Using erubis (2.7.0)
Using journey (1.0.3)
Using rack (1.4.1)
Using rack-cache (1.2)
Using rack-test (0.6.1)
Using hike (1.2.1)
Using tilt (1.3.3)
Using sprockets (2.1.2)
Using actionpack (3.2.3)
Using mime-types (1.18)
Using polyglot (0.3.3)
Using treetop (1.4.10)
Using mail (2.4.4)
Using actionmailer (3.2.3)
Using arel (3.0.2)
Using tzinfo (0.3.32)
Using activerecord (3.2.3) …我和我的几位同事最近在我们的Mac上使用自制程序从MySQL 5.5升级到MySQL 5.6,在升级服务器之前在本地进行测试.自从这次升级以来,我们在运行rails代码时都遇到了间歇性的MySQL错误:
Lost connection to MySQL server at 'sending authentication information', system error: 32
我们已经尝试在我们的数据库中重新创建用户名和密码,并提高连接超时,但都没有解决问题.错误日志没有提到问题.当我们遇到问题时,我们发现的唯一解决方法是杀死mysql并重新启动它.我最近mysql -u root -p在命令行上使用过这个错误.似乎一旦我开始收到此错误,无论我使用什么用户名,我都无法超过当前的连接数.如果我关闭连接,那么我可以重新打开一个连接.
我们有以下环境:
可能导致这种情况的任何想法？
谢谢!朱丽叶
当我尝试使用Mysql2作为数据库管理器在Rails中运行以下代码时:
rake db:migrate
我收到以下错误:
rake aborted!
"Mysql2::Error: All parts of a PRIMARY KEY must be NOT NULL:"
如果默认情况下表中的主键不是"null",为什么会出现此错误？
但是,迁移代码:
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string "first_name"
t.timestamps
end
end
end