Rails Git pre-commit hook for ensuring schema.rb and migration changes commit atomically

pre-commit

#!/usr/bin/env ruby
# based on https://gist.github.com/bestie/1223064

# Ensures that if a new migration is added, rake db:migrate is also run (and thus the schema.rb file is updated)

def schema_modified?
  %x[ git status |grep schema.rb ] != ''
end

# regex for typical migration
# db/migrate/20110901091759_remove_invalid_venue_phone_numbers.rb
# db\/migrate\/20[0-9]{12}_.*\.rb$
# or
# db\/migrate\/20[0-9]*
# Warning may only work for like 100 years or something.

def new_migrations_staged?
  %x[ git ls-files -o  --exclude-standard |grep 'db\/migrate\/20[0-9]*' ] != ''
end

if new_migrations_staged? && !schema_modified?
  puts
  puts "WARNING: Commit blocked"
  puts
  puts "Schema.rb not modified. Cannot submit new migration without also running it."
  puts
  puts "Run `rake db:migrate` to run your migration, then stage your schema.rb file, then try committing."
  puts
  exit 1
end

exit 0