Sunday, August 15, 2010

Factory Girl in Development

Some many developers use Factory Girl as a replacement to Fixtures and they depend on this gem in Test cases writing.

But Factory Girl can be very useful also in development and can be used in order to generate a bunch of dummy data with different specs for showing your work and reviewing all its details.

The problem we face is that Factory Girl can generate more records in tables that should have their data unchanged such as Countries table.

For example:

Factory.define :user do |f|
  f.association :country

Factory.define :job do |f|
  f.association :user

Now, when we run this piece of code that generates 10 jobs

10.times { Factory.create(:job) }

we will get 10 countries auto-generated
violating the rule we wish to maintain which is having the countries table as it is

To workaround this problem without causing any changes in the code written previously, i came up with that solution

class Factory
  class << self
    alias_method :create_original, :create
    def create(name, overrides = {})
      if name.to_s == 'country'
        country = Country.first
        return country if country

      create_original(name, overrides)

The logic introduced in the above script is simply adding a layer before creation that checks if the created object of certain type and if that type is desired to not be generated, we return the first entry we have in the DB else we do the normal creation

You can add this script in a file and load it in the development environment and use Factory Girl safely without fearing of generating data for tables that should remain as lookup tables

Enjoy :)

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