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 finally solved this problem, but not using the previously described methods.

Using brew install postgresql, I find out that it had already been installed, but not linked.

1. Find out where PostgreSQL is installed, and delete it,

2. Then brew install postgresql again,

3. brew link postgresql

4. gem install pg