Associations with default attributes

lib/oaken.rb

@@ -22,10 +22,31 @@ module Stored; end
   class Stored::Abstract
     def initialize(type)
       @type = type
+      @attributes = {}
+    end
+
+    def with(**attributes)
+      if block_given?
+        previous_attributes, @attributes = @attributes, @attributes.merge(attributes)
+        yield
+      else
+        @attributes = attributes
+      end
+    ensure
+      @attributes = previous_attributes if block_given?
     end
 
     def update(id, **attributes)
       self.class.define_method(id) { find(id) }
+
+      klass = nil
+      attributes = @attributes.merge(attributes)
+      attributes.transform_values! do |value|
+        if !value.respond_to?(:call) then value else
+          klass ||= Struct.new(:id, *attributes.keys).new(id, *attributes.values)
+          klass.instance_exec(&value)
+        end
+      end
     end
   end
 
@@ -35,7 +56,7 @@ def find(id)
     end
 
     def update(id, **attributes)
-      super
+      attributes = super
       objects[id] = @type.new(**attributes)
     end
 
@@ -50,7 +71,7 @@ def find(id)
     end
 
     def update(id, **attributes)
-      super
+      attributes = super
 
       if record = @type.find_by(id: id.hash)
         record.update!(**attributes)

test/oaken_test.rb

@@ -17,6 +17,26 @@ def test_that_it_has_a_version_number
 
   def test_accessing_fixture
     assert_equal "Kasper", users.kasper.name
+    assert_equal "Coworker", users.coworker.name
+
+    assert_equal [accounts.business], users.kasper.accounts
+    assert_equal [accounts.business], users.coworker.accounts
+    assert_equal [users.kasper, users.coworker], accounts.business.users
+  end
+
+  def test_default_attributes_last_into_test
+    users.update :homer
+    assert_equal [accounts.business], users.homer.accounts
+  end
+
+  def test_default_attributes_block
+    users.with accounts: [accounts.update(:home_co, name: "Yo")] do
+      users.update :homer
+    end
+    assert_equal [accounts.home_co], users.homer.accounts
+
+    users.update :homer
+    assert_equal [accounts.business], users.homer.accounts
   end
 
   def test_updating_fixture

test/seeds.rb

@@ -1 +1,5 @@
-users.update :kasper, name: "Kasper"
+accounts.update :business, name: "Big Business Co."
+
+users.with name: -> { id.to_s.capitalize }, accounts: [accounts.business]
+users.update :kasper
+users.update :coworker

test/test_helper.rb

@@ -10,6 +10,17 @@
 ActiveRecord::Base.logger = Logger.new(STDOUT)
 
 ActiveRecord::Schema.define do
+  create_table :accounts, force: true do |t|
+    t.string :name, null: false
+    t.timestamps
+  end
+
+  create_table :memberships, force: true do |t|
+    t.integer :account_id, null: false
+    t.integer :user_id,    null: false
+    t.timestamps
+  end
+
   create_table :users, force: true do |t|
     t.string :name, null: false
     t.timestamps
@@ -21,7 +32,19 @@
   end
 end
 
+class Account < ActiveRecord::Base
+  has_many :memberships, dependent: :destroy
+  has_many :users, through: :memberships, dependent: :destroy
+end
+
+class Membership < ActiveRecord::Base
+  belongs_to :account
+  belongs_to :user
+end
+
 class User < ActiveRecord::Base
+  has_many :memberships
+  has_many :accounts, through: :memberships
 end
 
 class Comment < ActiveRecord::Base