为什么在运行“捆绑安装”时会出现无法构建 gem 原生扩展错误 pg (0.8.0)？

Question

pg gem 没有在 gem 文件中指定，为什么它不会安装，如果它不在 gem 文件中，为什么它甚至会安装。 我正在尝试使用 mysql。

奇怪的是 pg gem 不在我的 gemfile 中，所以我认为它可能是另一个的依赖项，在研究了 gem 站点的依赖项之后，pg 显示不是使用的其他 gems 的依赖项。

错误信息：

Installing pg (0.8.0) with native extensions c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:543:in `rescue in block in build_e
xtensions': ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)

        c:/Ruby192/bin/ruby.exe extconf.rb
ERROR: can't find pg_config.
HINT: Make sure pg_config is in your PATH
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog

Gem files will remain installed in c:/Ruby192/lib/ruby/gems/1.9.1/gems/pg-0.8.0 for inspection.
Results logged to c:/Ruby192/lib/ruby/gems/1.9.1/gems/pg-0.8.0/ext/gem_make.out
        from c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:521:in `block in build_extensions'
        from c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:496:in `each'
        from c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:496:in `build_extensions'
        from c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:177:in `install'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/source.rb:96:in `install'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/installer.rb:55:in `block in run'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/spec_set.rb:12:in `block in each'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/spec_set.rb:12:in `each'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/spec_set.rb:12:in `each'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/installer.rb:44:in `run'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/installer.rb:8:in `install'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/cli.rb:225:in `install'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/vendor/thor/task.rb:22:in `run'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/vendor/thor/invocation.rb:118:in `invoke_task'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/vendor/thor.rb:246:in `dispatch'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/lib/bundler/vendor/thor/base.rb:389:in `start'
        from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.12/bin/bundle:13:in `<top (required)>'
        from c:/Ruby192/bin/bundle:19:in `load'
        from c:/Ruby192/bin/bundle:19:in `<main>'

这是gemfile：

source :rubygems

gem "rails", ">= 3.0"
gem "rack"
gem "clearance", "0.9.0.rc9"
gem "haml"
gem "high_voltage"
gem "hoptoad_notifier"
gem "will_paginate"
gem "formtastic"
gem "dynamic_form"
gem "mysql"

Answer 1

pg gem 用于从 ruby 访问 PostgreSQL 数据库。 检查您的 Gemfile.lock 以找出哪个 gem 需要它作为依赖项。

如果您确实需要使用 pg gem，请参阅此 Stack Overflow 问题。