gem install pg not working on Mac El Capitan - ruby-on-rails

Question

I tried to install pg Gem on Mac El Capitan, but I always get this error:
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb --with-pg-config=/Users/ricardolopes/Developer/homebrew/bin/pg_config
Using config values from /Users/ricardolopes/Developer/homebrew/bin/pg_config
checking for libpq-fe.h... yes
checking for libpq/libpq-fs.h... yes
checking for pg_config_manual.h... yes
checking for PQconnectdb() in -lpq... no
checking for PQconnectdb() in -llibpq... no
checking for PQconnectdb() in -lms/libpq... no
Can't find the PostgreSQL client library (libpq)
*** 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=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
--with-pg
--without-pg
--enable-windows-cross
--disable-windows-cross
--with-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}/
--with-pqlib
--without-pqlib
--with-libpqlib
--without-libpqlib
--with-ms/libpqlib
--without-ms/libpqlib
Gem files will remain installed in /Users/ricardolopes/Code/site-noticias/vendor/bundle/ruby/2.0.0/gems/pg-0.18.3 for inspection.
Results logged to /Users/ricardolopes/Code/site-noticias/vendor/bundle/ruby/2.0.0/gems/pg-0.18.3/ext/gem_make.out
An error occurred while installing pg (0.18.3), and Bundler cannot continue.
Make sure that gem install pg -v '0.18.3' succeeds before bundling.
I also tried:
ARCHFLAGS="-arch x86_64" gem install pg
When I tried it I got:
Building native extensions. This could take a while...
Successfully installed pg-0.18.3
invalid options: -f fivefish
(invalid options are ignored)
Parsing documentation for pg-0.18.3
Done installing documentation for pg after 3 seconds
1 gem installed
But I run bundle install and get the same error posted in the beginning of this post.
I tried reinstall PostgresSQL from brew.

Answer 1

Try this:
brew update
brew install postgresql
sudo gem install pg -v 'VERSION'

Answer 2

This worked for me:
sudo gem install pg -- --with-pg-config=/Applications/Postgres.app/Contents/Versions/9.4/bin/pg_config
Remember to change 9.4 to your postgres version, if different from 9.4.

Answer 3

For a basic Rails app, you probably already have SQLite installed, but in your Gemfile, it probably has simply:
gem 'sqlite3'
Do you just need PostgreSQL for production? Make sure your Gemfile has it as follows:
group :production do
gem 'pg'
end
Also, make sure your Gemfile has SQLite just for development:
group :development do
gem 'sqlite3'
end
then try running bundle install.