PostGreSQL error on railstutorial 3.2

gistfile1.txt

Installing pg (0.12.2) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /Users/toast/.rvm/rubies/ruby-1.9.2-p0/bin/ruby extconf.rb --without-pg-config
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/toast/.rvm/rubies/ruby-1.9.2-p0/bin/ruby
	--with-pg
	--without-pg
	--with-pg-dir
	--without-pg-dir
	--with-pg-include
	--without-pg-include=${pg-dir}/include
	--with-pg-lib
	--without-pg-lib=${pg-dir}/lib
	--with-pg-config
	--without-pg-config
	--with-pg_config
	--without-pg_config


Gem files will remain installed in /Users/toast/.rvm/gems/ruby-1.9.2-p0@rails3tutorial/gems/pg-0.12.2 for inspection.
Results logged to /Users/toast/.rvm/gems/ruby-1.9.2-p0@rails3tutorial/gems/pg-0.12.2/ext/gem_make.out

An error occured while installing pg (0.12.2), and Bundler cannot continue.
Make sure that `gem install pg -v '0.12.2'` succeeds before bundling.
toasts-spacbook:demo_app toast$ 

solved with this http://matthew.mceachen.us/blog/howto-wrangle-the-pg-postgresql-gem-with-macports-and-rvm-1159.html

sudo port install postgresql90

gem install pg -- --with-pg-config=/opt/local/lib/postgresql90/bin/pg_config