Can't find the 'libpq-fe.h header when trying to install pg gem

Question

I am using the Ruby on Rails 3.1 pre version. I like to use PostgreSQL, but the problem is installing the pg gem. It gives me the following error:

Answer 1

I encountered the same error with postgres installed through asdf. The pg-config solutions didn't work for me. Instead I had to locate the postgres include folder which contains the file and run the command with the --with-pg-include flag

gem install pg -- --with-pg-include=//.asdf/installs/postgres//include