Postgres rails socket problem

Postgres problem in rails

could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/pgsql_socket/.s.PGSQL.5432"?

Resolve:

mkdir /var/pgsql_socket/ 
ln -s /private/tmp/.s.PGSQL.5432 /var/pgsql_socket/

via: http://jaygoldman.com/2012/11/fixing-postgres-connection-errors-on-mountain-lion/