Rails 3.1 - Pushing to Heroku - Errors installing postgres adapter?

Question

I just upgraded to Rails 3.1 and the first app i've tried to deploy to Heroku has encountered a problem relating to Postgres adapter. I'm able to push the app to heroku but then when i try to migrate the database i get the following error:

heroku rake db:migrate

rake aborted! Please install the postgresql adapter: `gem install activerecord-postgresql-adapter`  (pg is not part of the bundle. Add it to Gemfile.) Tasks: TOP => db:migrate => db:load_config (See full trace by running task with --trace) 

when I try their suggested install i get:

ERROR:  Could not find a valid gem 'activerecord-postgresql-adapter' (>= 0) in any repository ERROR:  Possible alternatives: activerecord-postgis-adapter, activerecord-jdbcpostgresql-adapter, activerecord-postgresql-cursors, activerecord-jdbcmysql-adapter, activerecord-jdbcmssql-adapter 

which already seems weird... so what exact gem should I install to get this thing working if not what they say I should install??

When I try installing gem pg i get:

Building native extensions.  This could take a while... ERROR:  Error installing pg:         ERROR: Failed to build gem native extension.  /Users/jerometufte/.rvm/rubies/ruby-1.9.2-p180/bin/ruby extconf.rb 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     ... 

I'm using SQLite3 currently. Any help greatly appreciated, this is baffling me.

Answer 1

Option 1:

Add pg to your Gemfile but skip trying to install it locally.

$ cat Gemfile ... group :production do   # gems specifically for Heroku go here   gem "pg" end  # Skip attempting to install the pg gem $ bundle install --without production 

Option 2 (Debian/Ubuntu):

Add pg to your Gemfile but first install the prerequisites.

$ cat Gemfile ... group :production do   # gems specifically for Heroku go here   gem "pg" end  # Install the pg gem's dependencies first $ sudo apt-get install libpq-dev # Then install the pg gem along with all the other gems $ bundle install 

Answer 2

You definitely need pg in the Gemfile for Heroku.

About the error you're getting locally: make sure you have postgres installed, run gem install pq -- --with-pg-config=[path to wherever your pg-config binary is], then bundle install.

Alternatively, if your local database is working fine (either because you're using sqlite or postgres-pr), you could put the gem 'pg' line in your Gemfile in a group called production, then bundle install --without production locally.