FixtureSeed is a Rails gem that automatically loads YAML fixture files from the db/fixtures/ directory before running rails db:seed. It loads the fixtures in alphabetical order and handles foreign key constraint errors by retrying failed inserts after all other fixtures are loaded.

Add this line to your application's Gemfile:

gem 'fixture_seed'

And then execute:

$ bundle install

Once the gem is installed, it will automatically hook into Rails' db:seed task. You don't need to modify your seeds.rb file.

Place your YAML fixture files in the db/fixtures/ directory:

db/
  fixtures/
    posts.yml
    users.yml

The fixture files should be named after the table they correspond to (e.g., users.yml for the users table).

The content of the fixture files should follow this format:

# users.yml
user1:
  id: 1
  name: "John Doe"
  email: "john@example.com"

user2:
  id: 2
  name: "Jane Smith"
  email: "jane@example.com"

The labels (e.g., user1, user2) should follow the pattern of the table name in singular form followed by a number.

For dynamic fixture generation, you can use ERB templates in your YAML files:

# users.yml
<% 10.times do |i| %>
user<%= i + 1 %>:
  id: <%= i + 1 %>
  name: "User <%= i + 1 %>"
  email: "user<%= i + 1 %>@example.com"
  created_at: <%= Time.current.to_s(:db) %>
<% end %>

ERB templates have access to the full Rails environment, allowing you to use helpers, constants, and other Ruby code to generate dynamic fixture data.

FixtureSeed supports order-independent loading, which means you don't need to worry about the loading order of your fixture files based on database relationships.

1. Fixtures are initially loaded in alphabetical order by filename
2. When a fixture fails to load due to foreign key constraints, it's automatically retried later
3. The gem continues processing other fixtures and comes back to failed ones
4. This process repeats until all fixtures are loaded or no progress can be made

• No manual dependency management: You don't need to rename files or organize them based on foreign key relationships
• Simplified fixture organization: Focus on logical grouping rather than loading order
• Robust loading: Handles complex relationships automatically
• Error resilience: Temporary constraint violations don't stop the entire process

Even if your fixtures have dependencies like this:

db/fixtures/
  comments.yml    # depends on posts and users
  posts.yml       # depends on users  
  users.yml       # no dependencies

FixtureSeed will automatically handle the loading order, ensuring users.yml loads first, then posts.yml, and finally comments.yml, regardless of alphabetical order.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

Bug reports and pull requests are welcome on GitHub at https://github.com/komagata/fixture_seed.

The gem is available as open source under the terms of the MIT License.