While developing a Rails apps using PostgreSQL (unlike MySQL) I often run out of db connections and see errors like “FATAL:  remaining connection slots are reserved for non-replication superuser connections” and when I do, my Rails app stops working. Restarting Postgres fixing the problem, but it was harder to restart postgres that I expected. Here’s how I do it.

To restart PostgreSQL I added a function to my ~/.bash_profile file:

# restart postgres
pgr() {
  kill `ps -ef | grep postgres | grep -v grep | awk '{print $2}'`
}

After saving and restarting Terminal, running ‘pgr’ will find all the postgres process and kill them. Once launchd notices postgres is down it restarts it because I setup launchd to keep postgres running no matter what. If you don’t have postgres setup to stay running, you would need to start postgres whatever way matches your setup.

I tried a number of different solutions before I arrived at this one:

1. running ‘pg_ctl -D <path to db> restart’ would cause postgres to try and restart, but it would timeout unsuccessful
2. logging out then logging back in again works (since I’m running postgres as a ‘personal’ launch agent, it starts and stops with my login and logout) but that’s terribly disruptive to my work
3. killall would kill some, but not all of the errant postgres processes

I’m running OSX Lion, PostgreSQL 9.1.2, Rails 3.1.3, Ruby 1.9.2-p290.

I Googled the hive-mind for a better answer, after all, when developing a rails app using MySQL I had no such problem. It seems others have run into this, but I didn’t find a better solution. I have a nagging feeling there’s some setting I could add to my database.yml file to get PostgreSQL to behave well in my development environment and obviate the need for my PostgreSQL restarting shenanigans, but I’ve not yet discovered it.

I would like my Facebook Connect app to publish stories to my users’ Facebook news stream. I went looking for how do this with Facebooker and figured out an answer.

The old way of doing this, and the one built into Facebooker, is to publish a user action. There are two limitations of the old way: 1: you need a valid session_key (so, the user must be logged in); 2: you may only send up to 10 messages per day (without special permissions from the user).

Fortunately Facebook released their Open Stream API in April 2009 and it suffers from neither restriction: you can post without a session_key and there are no explicit limits on how many posts you can make in a day. Unfortunately Facebooker does not yet offer native support for publishing to Facebook streams, at least that I could find, but it DOES support rolling your own API calls, and in this case its not that hard to do. To post to a users’ Facebook stream from your Rails app’s script/console, do the following:

1. Integrate Facebooker into your Rails app.  Verify that it works.  There are a number of ways to integrate Facebooker depending on what kind of app you are making.  e.g. I’m making a Facebook Connect app, so I used AuthLogic and the AuthLogic Facebook Connect plugin so users can login to my app using their Facebook credentials.
2. Get a user’s permission to publish to their stream.  Make a note of their Facebook UID.  e.g. in my app, the AuthLogic Facebook Connect plugin stores the UID in my user table each time a new Facebook user logs into my site.
3. Run script/console and execute the following commands:

f = Facebooker::Session.create
f.post 'facebook.stream.publish', :uid => '<insert_facebook_uid_here>', :message => 'test'


Not so bad, huh?

Option #1: Use the gem as a plugin instead. Files that match the following pattern are automatically pulled in, so you’re good to go:

"#{RAILS_ROOT}/vendor/plugins/*/**/tasks/**/*.rake"

Option #2: Create a ruby file that loads the gem’s tasks, then require the ruby file you made in your rail app’s Rakefile.  For example, if you’ve installed the Facebooker gem and you want to use its rake tasks, you might create a file called ‘facebooker.rb’ and save it to your <railsapproot>/tasks directory with these contents:

$VERBOSE = nil
Dir["#{Gem.searcher.find('facebooker').full_gem_path}/lib/tasks/*.rake"].each { |ext| load ext }

Then add this line to your Rakefile:

require 'tasks/facebooker'

But as it turns out, Facebooker’s tasks uses relative paths to get at its config file in your rails app, which won’t work if its installed in the gem path as a gem rather than in your rails app as a plugin! So be careful with using option #2, it may not be what the gem you’re trying to use expects.

I too ran into some trouble before discovering that my beloved AuthLogic is validating my email field. The validation is a good thing overall, but I want to support blank email addresses as well as properly formatted ones.

It’s all in the AuthLogic docs of course, but if I can save you a few minutes of hunting around, that’s all good:


acts_as_authentic do |c|
  c.merge_validates_length_of_email_field_options({:allow_nil => true})
  c.merge_validates_format_of_email_field_options({:allow_nil => true})
end