test_query.rb

## Model

class User
  include DataMapper::Resource

  property :id, Serial
  property :first_name, String
  property :last_name, String

end


## How manage his query interface. Doing directly in User class and combine them ex :
#

class User
  include DataMapper::Resource

  property :id, Serial
  property :first_name, String
  property :last_name, String

  def self.with_first_name(name)
    all({:first_name => name})
  end

  def self.with_last_name(name)
    all({:last_name => name})
  end

end

User.with_first_name(name).with_last_name(name)

## Or create a new class to manage all Query stuff like :


class UserRequest
  def self.with_first_name(name)
    User.all({:first_name => name})
  end

  def self.with_last_name(name)
    User.all({:last_name => name})
  end
end

UserRequest.with_first_name(name).with_last_name(name)


## The second solution avoid put method in your model and separate your Query to your model