#1274 ✓resolved
Sylvain

has n and belongs_to with different name is not working well

Reported by Sylvain | May 18th, 2010 @ 04:49 PM

Here's a simple program:

require 'rubygems'
require 'dm-core'

DataMapper::Logger.new(STDOUT, :debug)
DataMapper.setup(:default, 'sqlite3::memory:')

class Rainbow
  include DataMapper::Resource
  property :id, Serial
  property :location, String

  has n, :colors
end


class Color
  include DataMapper::Resource
  property :id, Serial
  property :name, String

  belongs_to :beautiful_rainbow, 'Rainbow'
end

DataMapper.auto_migrate!

rainbow = Rainbow.new :location => "Paris"
rainbow.save!
color = Color.new :name => 'blue'
rainbow.colors << color
color.save!

color2 = Color.new :name => 'yellow'
color2.beautiful_rainbow = rainbow
color2.save!

when using dm-core 0.10.2, jruby 1.5.0,
here's the result:

 ~ (0.000) SELECT sqlite_version(*)
 ~ (0.000) DROP TABLE IF EXISTS "rainbows"
 ~ (0.000) DROP TABLE IF EXISTS "colors"
 ~ (0.000) CREATE TABLE "rainbows" ("id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, "location" VARCHAR(50))
 ~ (0.000) CREATE TABLE "colors" ("id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, "name" VARCHAR(50), "beautiful_rainbow_id" INTEGER NOT NULL, "rainbow_id" INTEGER NOT NULL)
 ~ (0.000) CREATE INDEX "index_colors_beautiful_rainbow" ON "colors" ("beautiful_rainbow_id")
 ~ (0.000) CREATE INDEX "index_colors_rainbow" ON "colors" ("rainbow_id")
 ~ (0.000) INSERT INTO "rainbows" ("location") VALUES ('Paris')
 ~ colors.beautiful_rainbow_id may not be NULL (code: 0, sql state: , query: INSERT INTO "colors" ("name", "rainbow_id") VALUES ('blue', 1), uri: )
C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:269:in `with_connection': colors.beautiful_rainbow_id may not be NULL (code: 0, sql state: , query: INSERT INTO "colors" ("name", "rainbow_id") VALUES ('blue', 1), uri: ) (DataObjects::SQLError)
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:59:in `execute'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:110:in `create'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:83:in `each'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:83:in `create'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/repository.rb:129:in `create'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:864:in `_create'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:927:in `save_self'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:912:in `_save'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:1085:in `run_once'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:911:in `_save'
        from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:362:in `save!'
        from C:\Documents and Settings\SYUD7403\My Documents\NetBeansProjects\datamapper_bug\lib\main.rb:30

if we remove color part (just color2), here's the result:

 ~ (0.000) SELECT sqlite_version(*)
 ~ (0.000) DROP TABLE IF EXISTS "rainbows"
 ~ (0.000) DROP TABLE IF EXISTS "colors"
 ~ (0.000) CREATE TABLE "rainbows" ("id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, "location" VARCHAR(50))
 ~ (0.000) CREATE TABLE "colors" ("id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, "name" VARCHAR(50), "beautiful_rainbow_id" INTEGER NOT NULL, "rainbow_id" INTEGER NOT NULL)
 ~ (0.000) CREATE INDEX "index_colors_beautiful_rainbow" ON "colors" ("beautiful_rainbow_id")
 ~ (0.000) CREATE INDEX "index_colors_rainbow" ON "colors" ("rainbow_id")
 ~ (0.000) INSERT INTO "rainbows" ("location") VALUES ('Paris')
 ~ colors.rainbow_id may not be NULL (code: 0, sql state: , query: INSERT INTO "colors" ("name", "beautiful_rainbow_id") VALUES ('yellow', 1), uri: )
C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:269:in with_connection': colors.rainbow_id may not be NULL (code: 0, sql state: , query: INSERT INTO &quot;colors&quot; (&quot;name&quot;, &quot;beautiful_rainbow_id&quot;) VALUES ('yellow', 1), uri: ) (DataObjects::SQLError)


    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:59:in `execute'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:110:in `create'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:83:in `each'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/adapters/data_objects_adapter.rb:83:in `create'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/repository.rb:129:in `create'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:864:in `_create'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:927:in `save_self'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:912:in `_save'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:1085:in `run_once'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:911:in `_save'
    from C:/jruby-1.5.0/lib/ruby/gems/1.8/gems/dm-core-0.10.2/lib/dm-core/resource.rb:362:in `save!'
    from C:\Documents and Settings\SYUD7403\My Documents\NetBeansProjects\datamapper_bug\lib\main.rb:34</code>

As you can see, the issue is that datamapper don't do the link from rainbow to color via "beautiful_raibow_id" but via "rainbow_id" which is wrong.

Comments and changes to this ticket

  • Dan Kubb (dkubb)

    Dan Kubb (dkubb) May 19th, 2010 @ 04:30 AM

    • State changed from “new” to “resolved”
    • Assigned user set to “Dan Kubb (dkubb)”

    The problem is that both sides of the relationship are using names that DataMapper cannot match up. It would have no way of knowing that :colors and :beautiful_rainbow are inverses without being told, since it is possible to have unidirectional relationships between models, and models can have multiple relationships between them with different names. (although it is advisable for clarity to always specify both sides of the relationship)

    You can specify the :inverse on the has() side of the relationship like this:

    has n, :colors, :inverse => :beautiful_rainbow

    Attached is the script provided, modified to work with this change.

  • Dan Kubb (dkubb)

    Dan Kubb (dkubb) May 19th, 2010 @ 04:32 AM

    BTW, I should also mention that it looks like you were using Resource#save! expecting that it would raise an exception when the resource is not saved, but what it actually does is executes the save method without any hooks or validation. Errors are more likely in this scenario, and will propagate up the stack, but it is probably better to only use Resource#save! in very limited cases.

  • Sylvain

    Sylvain May 19th, 2010 @ 07:42 AM

    Hi,
    Thanks for the answer,
    I search the way to give the "inverse" way to do that but didn't find it in the documentation.

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