Automatic associations in ruby on rails fixtures

Question

As described in this article, I am using automatic associations in fixtures. For example, if a region object has a country id, instead of doing "country_id": 1, I do "country": "USA". "USA" is a label in my countries.yml file, so fixtures knows how to take care of this. However, this only works when you do not specify an ID value for the countries object. So I cannot assign USA's ID to be 1. But if I do not assign it to be 1, it ends up being some large value 8974343...which is kinda strange. Is there a way to get fixtures to auto-generate id's that are not super high? ....or is this ok?

Answer 1

Reading the API documentation, this is exactly how autogenerated fixtures are supposed to behave -- if you want to have a specific ID value for a fixture in advance, you should probably just assign it yourself.

If not, well, from the API docs:

The generated ID for a given label is constant, so we can discover any fixture‘s ID without loading anything, as long as we know the label.

Answer 2

This is how you get an autogenerated id of the fixture label.

Fixtures.identify(:reginald)

Answer 3

Since I don't have enough reputation to comment, this is the actual Rails 4.1 documentation:

http://edgeapi.rubyonrails.org/classes/ActiveRecord/FixtureSet.html#class-ActiveRecord::FixtureSet-label-Fixture+label+interpolation

Under Fixture label interpolation:

monkey_id: <%= ActiveRecord::FixtureSet.identify(:reginald) %>
pirate_id: <%= ActiveRecord::FixtureSet.identify(:george) %>

Answer 4

The fixture's id comes directly from hashing its name (that's how "we can discover any fixture‘s ID without loading anything, as long as we know the label")

Answer 5

automated test to enforce fixture integrity

  class FixtureIntegrityTest < ActiveSupport::TestCase
    context "fixture integrity" do
      should "work" do
        fixtures = Dir["test/fixtures/*.yml"].map do |file|
          [file, File.basename(file).sub(/\..*/, "").singularize, YAML.load(ERB.new(File.read(file)).result)]
        end

        failures = fixtures.reject(&:last).map { |file,*| "#{file} is empty!"}

        failures = failures.presence || fixtures.map do |_, klass, content|
          content.select{ |_,fixture| fixture["id"] }.map do |name, _|
            fixtures.map do |file, _, content|
              content.select { |_,fixture| fixture[klass] == name }.map do |_, fixture|
                "#{file} uses #{klass}: #{name}, but should use the id!"
              end
            end
          end
        end.flatten.compact

        assert_equal [], failures
      end
    end
  end