我正在进行Hartl教程并已完成部署到Heroku的步骤。我在安装pg gem时遇到此错误。我已经尝试运行--without production命令，但我仍然收到此错误。我复制并粘贴了我的宝石文件，所以我知道语法中没有错误。
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
/Users/KohlKohlbrenner/.rvm/rubies/ruby-2.1.2/bin/ruby 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
--without-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/KohlKohlbrenner/.rvm/rubies/ruby-2.1.2/bin/ruby
--with-pg
--without-pg
--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/KohlKohlbrenner/.rvm/gems/ruby-2.1.2/gems/pg- 0.17.1 for inspection.
Results logged to /Users/KohlKohlbrenner/.rvm/gems/ruby-2.1.2/extensions/x86_64-darwin- 13/2.1.0-static/pg-0.17.1/gem_make.out
An error occurred while installing pg (0.17.1), and Bundler cannot continue.
Make sure that `gem install pg -v '0.17.1'` succeeds before bundling.