rails-database-seeding

Rails Database Seeding

Manage development and test data effectively.

Files: SKILL.md · EXAMPLES.md · references/workflow.md

HARD-GATE

NEVER commit production data to seeds
ALWAYS use factories for test-specific scenarios
ALWAYS make seeds idempotent (can run multiple times safely)

Quick Reference

Use	Solution
Static reference data	db/seeds.rb with find_or_create_by!
Test scenarios	FactoryBot in spec/factories/
Complex relationships	Both combined

Seeding Workflow

1. Write idempotent seeds — use find_or_create_by! so re-runs are safe.
2. Scope by environment — guard non-production data with Rails.env checks.
3. Run seeds — execute rails db:seed (or rails db:setup for a fresh database).
4. Validate idempotency — run rails db:seed a second time and confirm no duplicates or errors.
5. Verify data — open rails console and spot-check expected records exist with correct attributes.

See references/workflow.md for the complete seeding workflow.

Idempotent Seeds

# db/seeds.rb
admin = User.find_or_create_by!(email: 'admin@example.com') do |u|
  u.password = 'password'
  u.admin = true
end

Environment-Specific Seeds

# db/seeds.rb
if Rails.env.development?
  require Rails.root.join('db/seeds/development')
elsif Rails.env.test?
  require Rails.root.join('db/seeds/test')
end

# db/seeds/development.rb
10.times do
  User.find_or_create_by!(email: Faker::Internet.unique.email) do |u|
    u.password = 'password'
  end
end

FactoryBot Factory Example

# spec/factories/users.rb
FactoryBot.define do
  factory :user do
    email { Faker::Internet.unique.email }
    password { 'password' }

    trait :admin do
      admin { true }
    end
  end
end

# Usage in specs
create(:user, :admin)

Examples

See EXAMPLES.md for complete examples including:

• Environment-specific seed structure
• FactoryBot factories with traits
• Idempotent seed patterns
• Troubleshooting common issues

External References

• FactoryBot documentation
• Faker gem
• Rails Seeding Guide