Rails validation error messages: Displaying only one error message per field

Question

Rails displays all validation error messages associated with a given field. If I have three validates_XXXXX_of :email, and I leave the field blank, I get three

Answer 1

# Extracts at most one error message per field from the errors-object.
# @param  [ActiveModel::Errors] the_errors_object The errors-object.
# @raise  [ArgumentError] If the given argument is not an instance of ActiveModel::Errors.
# @return [Array] A string-array containing at most one error message per field from the given errors-object.
def get_one_error_per_field(the_errors_object)
  if the_errors_object.is_a? ActiveModel::Errors    
    errors = {}  
    the_errors_object.each do |field_name, associated_error|
      errors[field_name] = the_errors_object.full_message(field_name, associated_error) unless errors[field_name]
    end 
    return errors.values
  else
    raise ArgumentError.new('The given argument isn\'t an instance of ActiveModel::Errors!')
  end 
end