method
underscore
underscore(camel_cased_word)
public
Makes an underscored, lowercase form from the expression in the string.
Changes ‘::’ to ‘/’ to convert namespaces to paths.
underscore('ActiveModel') # => "active_model" underscore('ActiveModel::Errors') # => "active_model/errors"
As a rule of thumb you can think of underscore as the inverse of #camelize, though there are cases where that does not hold:
camelize(underscore('SSLError')) # => "SslError"