sequel-na-failure.rb

require 'sequel'
require 'sequel/extensions/migration'

DB = Sequel.sqlite

Sequel.migration do
  change do
    create_table(:classes, :ignore_index_errors => true) do
      primary_key :cid
    end
    
    create_table(:assignments) do
      primary_key :id
      foreign_key :classid, :classes, :null => false, :key => [:cid]
    end

    create_table(:assignment_class) do
      primary_key :id
      foreign_key :classid, :classes, :null => false, :key => [:cid]
      foreign_key :assignmentid, :assignments, :null => false, :key => [:id]
      String :name
    end

    create_table(:assignment_policy) do
      foreign_key :assignment_class_id, :assignment_class, :null => false, :key => [:id]
      TrueClass :printable
      primary_key [:assignment_class_id]
    end
  end
end

Sequel::Migration.descendants.each { |m| m.apply(DB, :up) }


module Models
  class Class < Sequel::Model
  end
  
  class Assignment < Sequel::Model
    plugin :nested_attributes
    one_to_one   :assignment_class, key: :assignmentid
    nested_attributes :assignment_class
  end

  class AssignmentClass < Sequel::Model(:assignment_class)
    plugin :nested_attributes
    many_to_one :assignment, key: :assignmentid
    one_to_one :assignment_policy
    nested_attributes :assignment_policy
  end

  class AssignmentPolicy < Sequel::Model(:assignment_policy)
    unrestrict_primary_key
    set_primary_key :assignment_class_id
  end
end

include Models

klass = Models::Class.create
assignment = Assignment.create(
  classid: klass.pk,
  assignment_class_attributes: {
    classid: klass.pk,
    name: 'assignment-class',
    assignment_policy_attributes: {
      printable: true
    }
  }
)
assignment.save.reload


assignment = Assignment.first
assignment.assignment_class_attributes = {
  :id   => assignment.assignment_class.pk,
  :assignmentid => assignment.pk,
  :classid => assignment.classid,
  :name => 'updated-assignment-class',
  :assignment_policy_attributes => {
    :assignment_class_id => assignment.assignment_class.pk,
    :printable           => false
  }
}

assignment.save # => Attempt to update object did not result in a single row modification (SQL: UPDATE "assignment_policy" SET "printable" = false, "reworkable" = true WHERE ("assignment_class_id" IS NULL))