Datamapper DataMapper

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  Carl Porth December 18th, 2009 @ 01:27 PM

  To clarify further:

  Let's say I'm using a 3rd party library which provides an adapter and some default models for a webservice for listing products (like google products). The webservice calls for a product_id with type String. On my db, I have on my own product model with product_id defined as an Integer. I would like to associate the two.

  It might look something like this:

    require 'rubygems'
    gem 'dm-core', '0.10.2'
    gem 'do_sqlite3', '0.10.0'
    require 'dm-core'
  
    module Webservice
      class Product
        include DataMapper::Resource
  
        def self.default_repository_name
          :webservice
        end
  
        property :id, String, :key => true
        property :name, String
        property :product_id, String
  
        belongs_to :product, 'Store::Product', :repository => :default
      end
    end
  
    module Store
      class Product
        include DataMapper::Resource
  
        property :id, Serial
        property :name, String
  
        has 1, :webservice_product, 'Webservice::Product', :repository => :webservice
      end
    end
  
    DataMapper.setup(:default, 'sqlite3::memory:')
    DataMapper.setup(:webservice, 'sqlite3::memory:')
  
    DataMapper.auto_migrate!
  
    Webservice::Product.create(:id => 'x', :name => 'foo', :product => Store::Product.create(:name => 'foo'))
  
    # in 0.10.1:
    Webservice::Product.first.product # => #<Store::Product @id=1 @name="foo">
  
    # in 0.10.2:
    Webservice::Product.first.product # => nil
  

  In 0.10.1, this type of association worked.
  In 0.10.2, this no longer works.

  I'm not sure it is a regression because the behavior is undefined.

  Is this a weird edge case not worth handling?

• 

  Dan Kubb (dkubb) February 5th, 2010 @ 02:13 AM

  • State changed from “new” to “not-applicable”

  Actually, in the future it will only be possible to join on properties that have the same type and the same constraints (like :min/:max for Integer, :length for String, etc). I recently reverted a commit that did implicit coercion between types in a join.

  I may add a way to explicitly coerce the types to another before joining them, but that will likely be after DM 1.0, and after we rework the query/adapter API to be built off veritas or something similar.