Hal Shearer and I monkey-patched Factory Girl’s sequencing capabilities to allow for pre-defined enumerations to loop through, instead of just infinitely incrementing numbers.
So instead of doing this:
Factory.sequence :email do |n| "person#{n}@example.com" end |
you could do something like this:
Factory.sequence(:email, ['angela', 'brett', 'alec']) do |name| "#{name}@example.com" end |
It will start over at the beginning when it’s gone through all of them:
>> Factory.next :email => "angela@example.com" >> Factory.next :email => "brett@example.com" >> Factory.next :email => "alec@example.com" >> Factory.next :email => "angela@example.com" >> Factory.next :email => "brett@example.com" |
You can also hand it a range (the internal implementation on this is none too efficient, so don’t give it billions at a time):
Factory.sequence(:email, 50..60) do |n| "user_#{n}@example.com" end >> Factory.next :email => "user_50@example.com" >> Factory.next :email => "user_51@example.com" >> Factory.next :email => "user_52@example.com" |
The infinitely incrementing counter is still available if you want it:
Factory.sequence(:email, %w[angela brett alec]) do |name,i| "#{name}_#{i}@example.com" end >> Factory.next :email => "angela_0@example.com" >> Factory.next :email => "brett_1@example.com" >> Factory.next :email => "alec_2@example.com" >> Factory.next :email => "angela_3@example.com" >> Factory.next :email => "brett_4@example.com" |
This sort of thing is useful when you want two different factories to use the same sequence and have some overlap between the two groups. For example, we need a bunch of email addresses to test on, many of which share the same domain:
Factory.sequence(:name, %w[angela brett alec hal debbie tracey jared]) do |name,i| "#{name}_#{i}" end Factory.sequence(:domain, %w[something.com example.com mydomain.com]) do |domain| domain end Factory.define(:email_address) do |f| f.address { "#{Factory.next(:name)}@#{Factory.next(:domain)}" } end >> 20.times { ea = Factory.build :email_address; puts ea.address } angela_0@something.com brett_1@example.com alec_2@mydomain.com hal_3@something.com debbie_4@example.com tracey_5@mydomain.com jared_6@something.com angela_7@example.com brett_8@mydomain.com alec_9@something.com hal_10@example.com debbie_11@mydomain.com tracey_12@something.com jared_13@example.com angela_14@mydomain.com brett_15@something.com alec_16@example.com hal_17@mydomain.com debbie_18@something.com tracey_19@example.com |
For our last trick, the reset method returns both the looping index and the infinite counter back to zero:
>> Factory.reset :name >> Factory.next :name => "angela_0" |
Here’s the code to make it happen:
class Factory def self.sequence(sequence_name, enum = nil, &blk) @@sequences ||= {} enum = enum.to_a @@sequences[sequence_name] = { :enum => enum, :index => 0, :infinite_counter => 0, :template => blk } end def self.next(sequence_name) seq = @@sequences[sequence_name] retval = case seq[:template].arity when 1 seq[:template].call(seq[:enum][seq[:index]]) when 2 seq[:template].call(seq[:enum][seq[:index]], seq[:infinite_counter]) end seq[:index] = (seq[:index]+1 == seq[:enum].size) ? 0 : seq[:index]+1 seq[:infinite_counter] += 1 @@sequences[sequence_name] = seq retval end def self.reset(sequence_name) @@sequences[sequence_name][:index] = 0 @@sequences[sequence_name][:infinite_counter] = 0 end end |
Just put that into some file–perhaps in your rails lib directory–and make sure that file gets required–probably in your rails config/environment.rb. When doing it by hand like this, you’ll want to make sure your library file is loaded after the factory_girl gem is loaded, or you’ll get weirdness like methods you’ve overridden acting in non-overridden ways and the like; config.after_initialize in your environment.rb’s Rails::Initializer block is your friend.
You can also now use the gem BrettRasmussen-factory_girl from gems.github.com. I mean to submit it as a patch back to the original factory_girl, which I’m sure I’ll have time to do Any Day Now.
Thanks for implementing a Genius idea and blogging about it! You guys rock!!! Go PMA!!
Comment by Jared Dobson — May 29, 2009 @ 2:06 pm
[...] Alphabet sequences with factorygirl Posted on September 3, 2010 I was trying to use this in a factorygirl class to create test data with names like Product A, Product B etc. This isn't very sophisticated. If you want some smarter dummy data generation with factorygirl, check out this post at the PMA media group. [...]
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