has_many association causing FactoryGirl beta to throw undefined local variable or method for FactoryGirl::SyntaxRunner

Factory Girl is powerful as heck, but it seems like some of the errors for has_many associations just come up as an error from FactoryGirl’s syntax runner. There are a bunch of different causes that come up from a few google searches, but here’s one that I hadn’t seen answered anywhere else. This could be caused by ruby 2.1, or by using the FactoryGirl beta 3.0.0, I’m not too sure.

I have an association:

to_do_item belongs_to to_do_list
to_do_list has_many to_do_items

I wanted a to_do_list factory that contained several to_do_items. You set this up with the after(:create)callback. For more information, see this excellent blog post from thoughtbot. My factory read like this:

FactoryGirl.define do
  factory :to_do_list do

  factory :three_item_list, parent: :to_do_list do
    after(:create) do |list|
      to_do_items << FactoryGirl.create(:to_do_item, {content: "item one", to_do_list: list, created_at: (DateTime.now - 1.hour)})
      to_do_items << FactoryGirl.create(:to_do_item, {content: "item two", to_do_list: list, created_at: (DateTime.now - 1.day)})
      to_do_items << FactoryGirl.create(:to_do_item, {content: "item three", to_do_list: list, created_at: (DateTime.now)})

The factory itself passes a .valid? call, but trying to use it threw the SyntaxRunner exception. After reading and re-reading the FactoryGirl readme a bunch, on a whim I tried out:

FactoryGirl.define do
  factory :to_do_list do

  factory :three_item_list, parent: :to_do_list do
    after(:create) do |list|
      list.to_do_items << FactoryGirl.create(:to_do_item, {content: "item one", to_do_list: list, created_at: (DateTime.now - 1.hour)})
      list.to_do_items << FactoryGirl.create(:to_do_item, {content: "item two", to_do_list: list, created_at: (DateTime.now - 1.day)})
      list.to_do_items << FactoryGirl.create(:to_do_item, {content: "item three", to_do_list: list, created_at: (DateTime.now)})

and my specs stopped throwing a SyntaxRunner exception and started failing as I’d expect them to. So there you go, it might be necessary in a has_many association to explicitly name the receiving object.

Postgres, Homebrew and Rails on Mac OS X Mavericks

I’ve normally been a mysql user, and know just enough admin stuff with mysql to get rails started up. Today, I taught mysql just enough postgres admin stuff to get up and running with postgres. Using homebrew complicates the process slightly.

Here’s what you expect from reading stackoverflow:

brew install postgresql
psql -U postgres

This won’t work. Neither will any solution like:

sudo su - postgres psql

The reason is that a lot of people are writing stack overflow from linux. Most linux package managers perform the following set of operations to install postgres:

  • create a postgres user
  • su to the postgres user
  • install postgres

The documentation for postgres tells you that You will need to become the operating system user under which PostgreSQL was installed (usually postgres) to create the first user account in order to access the default admin account.

Homebrew installs run as the a normal user account, by default. My default account name on my mac os box is james. As such, the default postgres admin login is james:

psql -U james

and that gets me logged in. The prompt shows a # sign when you’re logged in as the superuser role:

james$ psql
psql (9.3.4)
Type "help" for help.


What do you need to do now to get postgres set up for rails? Let’s assume you’re create a rails app called unimportant. Here’s what you need to do:

rails new unimportant --database=postgresql
cd unimportant
cat config/database.yml

Note that in database.yml, you’re specifically told that the database names you need to set up are:

<<: *default
database: unimportant_development

<<: *default
database: unimportant_test

<<: *default
database: unimportant_production
username: unimportant

So you need to make 3 new databases, and a user named “unimportant” who can access the production database. Assuming you’re running everything locally, here’s what you need to know. Postgres comes with some command line tools for making databases a little easier; it’s equivalent to writing the sql yourself:

createdb unimportant_development
createdb unimportant_test
createdb unimportant_production

Postgres also comes with a tool for making new users. We need an unimportant user:

createuser unimportant

You’re not done yet, though, because the unimportant user doesn’t have permission to write to the unimportant production database. First, let’s look at what postgres sees as permissions for our users. From the postgres pdf, chapter 20:
The concept of roles subsumes the concepts of “users” and “groups”. In PostgreSQL versions before 8.1, users and groups were distinct kinds of entities, but now there are only roles. Any role can act as a user, a group, or both.

So we’re actually looking for how to view roles. From the same chapter: To determine the set of existing roles, examine the pg_roles system catalog, for example SELECT rolname FROM pg_roles;
The psql program’s \du meta-command is also useful for listing the existing roles.

Let’s try it out:

james$ psql
psql (9.3.4)
Type "help" for help.

james=# \q
greentreeredsky:unimportant james$ psql -U james
psql (9.3.4)
Type "help" for help.

james=# \du
List of roles
Role name | Attributes | Member of
james | Superuser, Create role, Create DB, Replication | {}
unimportant | Create DB | {}

james=# SELECT rolname FROM pg_roles;
(2 rows)

james=# SELECT * FROM pg_roles;
rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcatupdate | rolcanlogin | rolreplication | rolconnlimit | rolpassword | rolvaliduntil | rolconfig | oid
james | t | t | t | t | t | t | t | -1 | ******** | | | 10
unimportant | f | t | f | f | f | f | f | -1 | ******** | | | 16389
(2 rows)

This is a bit difficult to read, sorry, but the last piece is telling us all the permissions that the admin user and the unimportant user have. In order for the unimportant user to actually be capable of managing the rails production db, it needs the rolcreatedb permission. To be able to log in to the psql command console you’ll need the rolcanlogin permission too. The postgresql documentation tells us to use the ALTER sql command to grant this, rather than the mysql GRANT command. The docs for ALTER tell us what roles we can add.

james=# alter role unimportant login;
james=# alter role unimportant createdb;

All done!

getopts and argv in bash

Let’s say you want to use getopts to parse ARGV in bash. Let’s say you also want a non-getopts argument. For example:

./foo.sh argument
./foo.sh -x argument
./foo.sh -abx argument

The non-optional argument is here always given as the last argument.
So, how do you retrieve that last argument after getopts is finished doing its work? Check it out, yo:

while getopts "ghr" opt; do
case $opt in
echo "Invalid option handed in. Usage:"


That last line is the magic. getopts sets $OPTIND to be the index of the last valid option. Index bash’s ARGV, fondly known as $@, in the position of $OPTIND and you’ll get the last item from ARGV.

rbenv fun

I just spent a wonderful day tackling a single problem. I wanted the rbenv install plugin to update itself. I decided that was a single instance of a broader problem, having rbenv plugins update automagically.


If I wanted a rbenv plugin to update automagically, though, surely I also wanted rbenv to update itself? Surely! That makes sense, after all!


The end result is three github repositories. First, a tools repository that contains a couple of scripts I wrote to help me write rbenv plugins. It is here https://github.com/jamandbees/rbenvdevtools.

Second, a repository with a rbenv plugin that does a self update. https://github.com/jamandbees/rbenv-selfupdate

Third, a repository with a rbenv plugin that updates rbenv plugins. https://github.com/jamandbees/rbenv-plugins



Rails And Rake Redux

Okay, so it turned out that reading the rake documentation was helpful as heckfire.

  • Rails generates a rakefile by default. It contains:
  • require File.expand_path('../config/application', __FILE__)

  • File.expand_path retrieves an absolute path. The second argument __FILE__ is the place for expand_path to start searching. This expands to /path/to/rails/app/Rakefile
  • The first argument to expand_path is ‘../config/application’. The .. means “/path/to/rails/app/Rakefile” becomes “/path/to/rails/app”. Then “/config/application” is appended.
  • Once the application config is retrieved, then the task YourAppNameSpace::Application.load_tasks is performed. This loads the rake tasks so that rake -vT can see ’em.

How Does Rake Initialise a Rails App?

Rake is apparently simple, used all over the place, and a bit fiddly. Whenever you run a rake task, the entire rails application is initialised in the background. But how? HOW?!

  1.  It’s not the namespace you’re using. Arbitrary namespaces all initialise the rails app.
  2. Therefore, somehow, somewhere, something is happening in some parent task that everything is pulling in. But what?

Well, there’s no specific mechanism in rake that I’m aware of that arbitrary tasks inherit from. So it’s either the case that there’s a mechanism I don’t know about, or it’s the case that the rake tool has been monkeypatched somehow.

The case for rake being monkeypatched seems promising. How does rake -vT know to look in lib/tasks for extra tasks? Rails configuration, that’s how. So, how do you configure rake this way? I want to start by working out where a standard rake task is defined, so I try:

rake --where db:migrate

From here, I can see that railties is responsible for the db tasks. I also try:

rake --where log:clear

and it’s clear again that railties is coming into play. I’ve got a vague idea from the name, and my own reading, that railties is some kind of glue for rails. So, let’s dig a little deeper. I’ve opened my text editor to the location of the railties gem (it’s in the path given out by rake –where log:clear), and there’s a readme. It confirms that railsties is a glue gem.

I search for all files beginning with Rake, just because I’ve got to start somewhere, and find a rakefile in lib/rails/generators/rails/app/templates/ which has the line <%= app_const %>.load_tasks. This reads like an erb template, and I’m not specifically interested save that it gives me a clue: presumably, tasks are discovered by rails using a load_tasks method. Searching for “def load_tasks” in railties reveals:

# Load the application and its railties tasks and invoke the registered hooks.
# Check Rails::Railtie.rake_tasks for more info.
def load_tasks(app=self)

I can buy that initialize_tasks is going to be where I need to start. I search for def initialize_tasks and find:

def initialize_tasks #:nodoc:
self.class.rake_tasks do
require "rails/tasks"
task :environment do
$rails_rake_task = true

require_environment!? What does that sound like it does?

def require_environment! #:nodoc:
environment = paths["config/environment"].existent.first
require environment if environment

The namespace we’re in right now is “class Application < Engine”.

I can buy that this is where the environment is getting pulled in for _something_. I don’t know whether it’s the current app I’m working on, some rails-y magic or whatever. However, this doesn’t specifically help me out right now, because I’m trying to prevent rails loading for a rake task. rake task:name will still need to know how to load the rakefile in order to make any progress, which requires that the rails app has loaded. I’ve got a little further on the path to accomplishing my goal, but I’m not quite there.


Of course, I could just be overcomplicating things and there’s simply a Rakefile in rails root. And this slurps in the application config. Curses!