DataMapper With ruby sinatra Many to many :trough => Reasource

Question

I am trying to create a new user group many to many relation. I am using these dataMapper Objects

module Core_authentication

  class User
    include DataMapper::Resource

    property :id, Serial
    property :username, String
    property :password, BCryptHash
    property :email, String
    property :created_at, DateTime
    property :updated_at, DateTime

    #Creating join tables to link to group and person information
    has n, :Person, :through => Resource
    has n, :Group, :through => Resource
  end  

  class Group
    include DataMapper::Resource

    property :id, Serial
    property :name, String

    #Another jointable link group to link to functions and classification levels
    has n, :Function, :through => Resource
    has n, :Classificationlevel, :through => Resource
  end  

  class Person
    include DataMapper::Resource

    property :id, Serial
    property :firstname, String
    property :lastname, String
    property :adress, String
    property :postcode, String
    property :telefoon, String
    property :created_at, DateTime
    property :updated_at, DateTime

  end  

  class Function
    include DataMapper::Resource

    property :id, Serial
    property :name, String

  end  

  class Classificationlevel
    include DataMapper::Resource

    property :id, Serial
    property :levelcode, String
    property :name, String

  end

end

and these code to create and fill the tables

user = Core_authentication::User.create
user.username = params['username']
user.password = params['password']
user.email = params['email']
#user.save

group = Core_authentication::Group.first_or_create(:name => params['group'])
group.name = params['group']
group.save

user.Group << group

But when i want try it gives me this error

NoMethodError at /register
undefined method `group' for #<Core_authentication::User:0x007f96cc2bf920>

    file: App.rb
    location: block in <class:App>
    line: 46

So it fails on the point where i need to join the tables into a table with both ids. Why does it do this and wat is a possible solution? Is that i placed the DataMapper object in a module the problem?

Answer 1

Fixed the problem after lots of try's It was Fixed by using has n, :model, through => Resource and placing it at both model classes.

This wil create a join table containing both resource ids here a small example.

module Core_authentication

  class User
    include DataMapper::Resource

    property :id, Serial
    property :username, String, :required => true, :unique => true  
    property :password, BCryptHash, :required => true 
    property :email, String, :format => :email_address, :required => true
    property :created_at, DateTime
    property :updated_at, DateTime

    #Creating join tables to link to group and person information
    has n, :persons, :through => Resource

  end 

  class Person
    include DataMapper::Resource

    property :id, Serial
    property :firstname, String
    property :lastname, String, :required => true
    property :adress, String
    property :postcode, String, :length => 6, :required => true
    property :telefoon, String
    property :created_at, DateTime
    property :updated_at, DateTime

    has n, :users, :through => Resource

  end  

Then just create the 2 objects then link the objects by

user.persons << person

and then save