无法在Rails上安装pg gem

Question

我试图捆绑安装，但是，由于一些奇怪的原因，pg gem在安装时返回以下错误：

$ gem install pg -v '0.18.4'
Building native extensions.  This could take a while...
ERROR:  Error installing pg:
    ERROR: Failed to build gem native extension.

    /Users/username/.rvm/rubies/ruby-2.2.1/bin/ruby -r ./siteconf20151221-23315-1tkv3fd.rb extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** 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
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/Users/username/.rvm/rubies/ruby-2.2.1/bin/$(RUBY_BASE_NAME)
    --with-pg
    --without-pg
    --enable-windows-cross
    --disable-windows-cross
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib

extconf failed, exit code 1

Gem files will remain installed in /Users/username/.rvm/gems/ruby-2.2.1/gems/pg-0.18.4 for inspection.
Results logged to /Users/username/.rvm/gems/ruby-2.2.1/extensions/x86_64-darwin-15/2.2.0/pg-0.18.4/gem_make.out

任何人都可以帮我安装这个宝石并使我的捆绑成功完成？

Answer 1

您应该安装PostgreSQL开发库。

如果您使用的是Ubuntu，这将有助于：

sudo apt-get install libpq-dev

在Mac上：

brew install postgresql

Answer 2

您需要正确配置pg。

跑：

bundle config build.pg --with-pg-config=/Applications/Postgres.app/Contents/Versions/(YOUR POSTGRES VERSION)/bin/pg_config

然后尝试运行bundle：

bundle install

Answer 3

如果安装了PostgreSQL客户端库，那么你需要告诉gem在哪里查找包含文件，它通过询问pg_config 。 我使用一个小shell文件使gem更容易找到该实用程序：

#!/bin/sh -x

PATH=/Library/PostgreSQL/9.4/bin:$PATH
gem install pg $@

您也可以手动调整PATH以始终包含PostgreSQL bin目录，该目录应永久修复问题。

如果升级PostgreSQL，该路径将发生变化，因此您可能需要重新安装pg和/或更改PATH设置。

一旦安装了pg，就可以在不重新运行脚本的情况下安装进一步的gem升级。