Basically the type coercion on assignment is causing items that should not be valid to appear valid

class Company
  include Mongoid::Document
  field :revenue, type: Float
  validates_numericality_of :revenue
end

company = Company.new revenue: 'one million dollars'
company.valid? # => true

The company is showing up as valid even though it is not, due to the model not responding to company.revenue_before_type_cast and the type cast on assignment forcing the string to 0.