snippet.rb

## DataMapper 0.10.2 & ASSOCIATIONS
#
# I'm working on a Client model, and need to track the Nationality of the Client, 
# but don't really want to create an un-necessary Nationality model, when I theoretically 
# can use the existing Country model.
#
# All the variations I've tried causes a similar error:
#
#   Cannot add a NOT NULL column with default value NULL (DataObjects::SyntaxError)
# 
# How to overcome this error ??
# 
# Using SQLite3 as the DB
# 
# 
# /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:124:in `execute_non_query': Cannot add a NOT NULL column with default value NULL (DataObjects::SyntaxError)
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:124:in `upgrade_model_storage'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:118:in `map'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:118:in `upgrade_model_storage'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:269:in `with_connection'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:117:in `upgrade_model_storage'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:1302:in `upgrade_model_storage'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:1373:in `auto_upgrade!'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:45:in `send'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:45:in `repository_execute'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/model/descendant_set.rb:33:in `each'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/model/descendant_set.rb:33:in `each'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:44:in `repository_execute'
#   from /Library/Ruby/Gems/1.8/gems/dm-core-0.10.2/lib/dm-core/migrations.rb:27:in `auto_upgrade!'




class Client
  include DataMapper::Resource
  property :id,                   Serial
  property :name,                 String
  # # The nationality of the client, taken from the Country model
  property :nationality,          String, :default => "MY", :length => 2 
  
  ## ASSOCIATIONS
  
  # a Client can only have one nationality (in this case at least)
  
  # has 1, :nationality, 'Country' 
  # has 1, :nationality, :model => 'Country' #, :foreign_key => :code 
  belongs_to :nationality, :model => 'Country', :foreign_key => :code
  # belongs_to :nationality, :model => 'Country'#, :child_key => :code
  
end

class Country
  include DataMapper::Resource
  # The two letter unique code for the country
  property :code,     String, :key => true
  # The name of the country
  property :name,    String
  
  ## ASSOCIATIONS
  
  has n, :clients
  
end #/ Country