validation - Ruby on Rails - Validate a Cost

Question

What is the best way to validate a cost/price input by a user, validation rules below:

• Examples of formats allowed .23, .2, 1.23, 0.25, 5, 6.3 (maximum of two digits after decimal point)
• Minimum value of 0.01
• Maximum value of 9.99

Answer 1

Check the price and verify the format

#rails 3    
validates :price, :format => { :with => /Ad+(?:.d{0,2})?z/ }, :numericality => {:greater_than => 0, :less_than => 10}

#rails 2
validates_numericality_of :price, :greater_than => 0, :less_than => 10    
validates_format_of :price, :with => /Ad+(?:.d{0,2})?z/