Gem :: 从 MySQL 迁移到 MongoDB 时出现加载错误答案

【问题标题】：Gem :: load error while migrating from MySQL to MongoDBGem :: 从 MySQL 迁移到 MongoDB 时出现加载错误
【发布时间】：2018-08-08 13:29:02
【问题描述】：

我正在尝试使用工具 Mongify 将 Mysql DB 迁移到 MongoDB，方法是参考 documentation：

我已经看到，关于此类迁移的帖子已经很少，但他们提到了 Rails 应用程序的问题以及对 Rails 的一些依赖关系。但是，就我而言，这只是没有 Rails 的简单迁移。

环境详情：

Windows 企业版 7
Mysql 社区服务器：5.7
Mongo 数据库服务器：4.0
ruby : ruby 2.5.1p57（2018-03-29 修订版 63029）[i386-mingw32]
Mysql c 连接器（32 位）

mysql 服务器和 mongo db 服务器作为服务运行良好。

rubygems 环境详情如下：

RubyGems Environment:
  - RUBYGEMS VERSION: 2.7.6
  - RUBY VERSION: 2.5.1 (2018-03-29 patchlevel 57) [i386-mingw32]
  - INSTALLATION DIRECTORY: C:/Ruby25/lib/ruby/gems/2.5.0
  - USER INSTALLATION DIRECTORY: C:/Users/irfan.sayed/.gem/ruby/2.5.0
  - RUBY EXECUTABLE: C:/Ruby25/bin/ruby.exe
  - EXECUTABLE DIRECTORY: C:/Ruby25/bin
  - SPEC CACHE DIRECTORY: C:/Users/irfan.sayed/.gem/specs
  - SYSTEM CONFIGURATION DIRECTORY: C:/ProgramData
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86-mingw32
  - GEM PATHS:
     - C:/Ruby25/lib/ruby/gems/2.5.0
     - C:/Users/irfan.sayed/.gem/ruby/2.5.0
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - https://rubygems.org/
  - SHELL PATH:
     - C:\windows\system32
     - C:\windows
     - C:\windows\System32\Wbem
     - C:\Program Files (x86)\Microsoft Application Virtualization Client
     - C:\Program Files\PuTTY\
     - C:\apache-maven-3.5.2-bin\apache-maven-3.5.2\bin
     - "C:\Program Files\Java\jdk1.8.0_151\bin"
     - C:\Program Files\Git\cmd
     - C:\HashiCorp\Vagrant\bin
     - C:\windows\System32\WindowsPowerShell\v1.0\
     - C:\windows\System32\WindowsPowerShell\v1.0\
     - C:\Ruby25\bin
     - C:\Program Files\MySQL\MySQL Server 8.0\bin
     - C:\Program Files\MongoDB\Server\4.0\bin

本地安装的 Gems 如下：

activemodel (5.2.1, 4.2.10)
activerecord (5.2.1, 4.2.10)
activerecord-mysql2-adapter (0.0.3)
activesupport (5.2.1, 4.2.10)
arel (9.0.0, 6.0.4)
awesome_print (1.8.0)
backports (3.11.3)
bigdecimal (default: 1.3.4)
bson (1.12.5)
bson_ext (1.12.5)
builder (3.2.3)
bundler (1.16.3)
byebug (10.0.2)
cmath (default: 1.0.0)
coderay (1.1.2)
concurrent-ruby (1.0.5)
coolline (0.5.0)
csv (default: 1.0.0)
cucumber (3.1.2)
cucumber-core (3.2.0)
cucumber-expressions (6.0.1)
cucumber-tag_expressions (1.1.1)
cucumber-wire (0.0.1)
date (default: 1.0.0)
dbm (default: 1.0.0)
did_you_mean (1.2.0)
diff-lcs (1.3)
etc (default: 1.0.0)
fcntl (default: 1.0.0)
fiddle (default: 1.0.0)
fileutils (default: 1.0.2)
gdbm (default: 2.0.0)
gherkin (5.1.0)
highline (1.7.8)
i18n (0.9.5, 0.7.0)
io-console (default: 0.4.6)
ipaddr (default: 1.2.0)
jazz_fingers (5.0.0)
json (default: 2.1.0)
metaclass (0.0.4)
method_source (0.9.0)
minitest (5.11.3, 5.10.3)
mocha (1.6.0)
mongify (1.3.2)
mongo (1.12.5)
multi_json (1.13.1)
multi_test (0.1.2)
mysql (2.9.1 x86-mingw32)
mysql2 (0.5.2 x86-mingw32)
net-telnet (0.1.1)
openssl (default: 2.1.0)
pg (1.0.0 x86-mingw32)
power_assert (1.1.1)
pry (0.11.3)
pry-byebug (3.6.0)
pry-coolline (0.2.5)
psych (default: 3.0.2)
rake (12.3.1, 12.3.0, 11.3.0)
rdoc (default: 6.0.1)
rspec (2.99.0)
rspec-collection_matchers (1.1.3)
rspec-core (2.99.2)
rspec-expectations (2.99.2)
rspec-mocks (2.99.4)
scanf (default: 1.0.0)
sdbm (default: 1.0.0)
sqlite3 (1.3.13 x86-mingw32)
stringio (default: 0.0.1)
strscan (default: 1.0.0)
test-unit (3.2.7)
thread_safe (0.3.6)
tzinfo (1.2.5)
unicode_utils (1.4.0)
watchr (0.7)
webrick (default: 1.4.2)
xmlrpc (0.3.0)
yard (0.9.15)
zlib (default: 1.0.0)

bundle install 和 bundle update 命令运行良好。所有依赖项都是 gem 已正确解析并在 ruby 的默认文件夹中可用。

database.config 文件使用如下：

sql_connection do
  adapter   "mysql2"
  host      "localhost"
  username  "root"
  password  "<password>"
  database  "abc"
end

mongodb_connection do
  host      "localhost"
  database  "db"
end

但是出现以下错误：

mongify check database.config
Traceback (most recent call last):
        10: from C:/Ruby25/bin/mongify:23:in `<main>'
         9: from C:/Ruby25/bin/mongify:23:in `load'
         8: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/mongify-1.3.2/bin/mongify:17
:in `<top (required)>'
         7: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/mongify-1.3.2/lib/mongify/cl
i/application.rb:28:in `execute!'
         6: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/mongify-1.3.2/lib/mongify/cl
i/command/worker.rb:68:in `execute'
         5: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/mongify-1.3.2/lib/mongify/cl
i/command/worker.rb:99:in `check_sql_connection'
         4: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/mongify-1.3.2/lib/mongify/da
tabase/sql_connection.rb:56:in `has_connection?'
         3: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/mongify-1.3.2/lib/mongify/da
tabase/sql_connection.rb:40:in `setup_connection_adapter'
         2: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/activerecord-4.2.10/lib/acti
ve_record/connection_handling.rb:50:in `establish_connection'
         1: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/activerecord-4.2.10/lib/acti
ve_record/connection_adapters/connection_specification.rb:174:in `spec'
C:/Ruby25/lib/ruby/gems/2.5.0/gems/activerecord-4.2.10/lib/active_record/connect
ion_adapters/connection_specification.rb:177:in `rescue in spec': Specified 'mys
ql2' for database adapter, but the gem is not loaded. Add `gem 'mysql2'` to your
 Gemfile (and ensure its version is at the minimum required by ActiveRecord). (G
em::LoadError)

无法理解仍然缺少什么。是 MySQL 适配器的问题还是某些版本兼容性问题

编辑：根据 matthewd 的建议进一步更新

我编辑了 Gemfile 并添加了以下行

s.add_development_dependency('mysql2', '~> 0.4.10')

运行了 bundle update --force , bundle install --force 但它仍然只安装 mysql2 gem 的 0.5.x 版本所以我使用以下命令手动安装了 0.4.10 版本的 mysql2 gem

gem install mysql2 -v 0.4.10

但现在它给出了以下错误

        11: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/mysql2-0.4.10-x86-mingw32/li
b/mysql2.rb:31:in `<top (required)>'
        10: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/activesupport-4.2.10/lib/act
ive_support/dependencies.rb:274:in `require'
         9: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/activesupport-4.2.10/lib/act
ive_support/dependencies.rb:240:in `load_dependency'
         8: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/activesupport-4.2.10/lib/act
ive_support/dependencies.rb:274:in `block in require'
         7: from C:/Ruby25/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59
:in `require'
         6: from C:/Ruby25/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59
:in `require'
         5: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/mysql2-0.4.10-x86-mingw32/li
b/mysql2/mysql2.rb:2:in `<top (required)>'
         4: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/activesupport-4.2.10/lib/act
ive_support/dependencies.rb:274:in `require'
         3: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/activesupport-4.2.10/lib/act
ive_support/dependencies.rb:240:in `load_dependency'
         2: from C:/Ruby25/lib/ruby/gems/2.5.0/gems/activesupport-4.2.10/lib/act
ive_support/dependencies.rb:274:in `block in require'
         1: from C:/Ruby25/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59
:in `require'
C:/Ruby25/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require': Co
uld not load 'active_record/connection_adapters/mysql2_adapter'. Make sure that
the adapter in config/database.yml is valid. If you use an adapter other than 'm
ysql', 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the
Gemfile. (LoadError)

【问题讨论】：

标签： mysql ruby mongify

【解决方案1】：

错误消息具有误导性：您使用的 mysql2 gem 版本对于 Active Record 4.2.10 来说太新（最新版本 mongify 支持）。

最简单的解决方案是通过在您的 Gemfile 条目中包含版本约束来显式使用旧版本的 mysql2：

gem "mysql2", "< 0.5"

【讨论】：

感谢@matthewd。我根据您的建议更新了答案。仍然出现新错误。请建议
您描述的更改与上述不符。您需要将我显示的行添加到名为 Gemfile 的文件中。
谢谢。你能检查一下这个pastebin吗：pastebin.com/vTey9cDa
我已经修改了 mongify.gemspec 文件并为 mysql2 添加了行。你能检查一下这个pastebin吗：pastebin.com/vTey9cDa
我说“将我显示的行添加到名为 Gemfile 的文件中”。你说“我已经修改了 mongify.gemspec 文件”。我不能再帮忙了。

【解决方案2】：

终于解决了。它有 ruby 版本和 32 位库的问题。 ruby 2.3 已经过适当的测试，并且可以与 mongify gem 一起正常工作。我使用的是最新版本的 ruby，这就是问题所在。

【讨论】：