So I am working on a Rails project that revolves around an acts_as_tree using single table inheritence (STI). I got tired REALLY quickly with figuring out what id to use for each parent_id field. I figured that in the spirit of Don’t Repeat Yourself I would come up with a DRY way to specify the parents that did not require reapplying the id’s to the fixtures when I change things.

Since the YAML fixtures in ruby are parsed through eRb first, I thought I would give this a try. I made a file called thing_data.yml with my fixtures like so:

root:
  name: root item
  parent_id:
first_branch:
  name: a branch
  parent_id: root
second_branch:
  name: another branch
  parent_id: root
a_leaf:
  name: a leaf on the wind
  parent_id: first_branch

Notice the utter lack of ids. Now with a little eRb magic we put the following in the yaml file you plan to load as your fixture. Lets call it thing.yml:

<%

id_key = 1

data = YAML.load_file(
  File.expand_path(
    File.dirname( __FILE__ ) + '/test/fixtures/thing_data.yml'
  )
)

@final = Hash.new
data.each {|key, value|

  record = Hash.new

  record.update( value )
  record['id'] = id_key
  record[ 'created_at' ] = Time.now.strftime("%Y-%m-%d %H:%M:%S")
  record[ 'updated_at' ] = Time.now.strftime("%Y-%m-%d %H:%M:%S")

  @final[ key ] = record

  id_key = id_key.next
}  

thing_ids = Hash.new

@final.each { |key, value|
  thing_ids[ key ] = value[ 'id' ]
}

@final.each { |key, value|
  value[ 'parent_id' ] = thing_ids[ value[ 'parent_id' ] ]
}
%>
<%= @final.to_yaml %>

To test, run erb thing.yml and see your output. No more hand coding of ids and hoping you didn’t put something in the wrong place!

[tags]ruby, rails, dry, fixtures, testing[/tags]

“Interuption is not work.”

“Collabrative software turns collaboration into a passive activity, not an active activity.”

Check it out here.

Glad to see someone else has done the math, especially with the number of people who are facing foreclosures of late.

http://www.investorgeeks.com/articles/2006/05/23/renting-is-for-suckers/

Once again the RIAA and MPAA are trying to limit the things you can do with the media you have already paid for. Check out this fun cartoon from the Electronic Frontier Foundation.