[ruby-on-rails] Deleting all records in a database table

How do I delete all records in one of my database tables in a Ruby on Rails app?

BlogPost.find_each(&:destroy)

If you mean delete every instance of all models, I would use

ActiveRecord::Base.connection.tables.map(&:classify)
  .map{|name| name.constantize if Object.const_defined?(name)}
  .compact.each(&:delete_all)

More recent answer in the case you want to delete every entries in every tables:

def reset
    Rails.application.eager_load!
    ActiveRecord::Base.descendants.each { |c| c.delete_all unless c == ActiveRecord::SchemaMigration  }
end

More information about the eager_load here.

After calling it, we can access to all of the descendants of ActiveRecord::Base and we can apply a delete_all on all the models.

Note that we make sure not to clear the SchemaMigration table.

If your model is called BlogPost, it would be:

BlogPost.all.map(&:destroy)

To delete via SQL

Item.delete_all # accepts optional conditions

To delete by calling each model's destroy method (expensive but ensures callbacks are called)

Item.destroy_all # accepts optional conditions

All here

if you want to completely empty the database and not just delete a model or models attached to it you can do:

rake db:purge

you can also do it on the test database

rake db:test:purge