From 645fb60981cc5bdab1bbd44579bcfb96ed24d618 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thibaut=20Barr=C3=A8re?= <thibaut.barrere@gmail.com>
Date: Wed, 11 Mar 2009 12:51:46 +0100
Subject: [PATCH] Now able to specify AR model + key on DataPatcher
 instanciation. Tests cleanup. We're mostly done.

---
 lib/data_patcher.rb             | 25 ++++++++++++-----------
 spec/data_patcher_spec.rb       | 35 +++++++++++----------------------
 spec/migrations/create_items.rb |  7 -------
 spec/spec_helper.rb             | 14 +++++++++++++
 4 files changed, 39 insertions(+), 42 deletions(-)

diff --git a/lib/data_patcher.rb b/lib/data_patcher.rb
index 37a58d4..efd3dc9 100644
--- a/lib/data_patcher.rb
+++ b/lib/data_patcher.rb
@@ -1,9 +1,19 @@
-require 'activesupport'
+require 'active_record'
+require 'active_support'
 
 class DataPatcher
+  attr_reader :model, :key, :patch
   
-  def analyze_record(key, attributes)
-    existing = Item.find_by_asin(attributes[key])
+  # model: activerecord class
+  # key: unique key accross all model instances
+  def initialize(model, key)
+    @model = model
+    @key = key
+    @patch = {}
+  end
+    
+  def analyze_record(attributes)
+    existing = model.find(:first, :conditions => { key => attributes[key] })
     if existing
       existing_attributes = existing.attributes.dup.symbolize_keys.except(:id)
       diff = attributes.diff(existing_attributes)
@@ -19,14 +29,5 @@ def analyze_record(key, attributes)
     end
   end
   
-  # test commodity - remove ?
-  def analyze_records(key, records)
-    records.each { |record| analyze_record(key, record) }
-  end
-  
-  def patch
-    @patch ||= {}
-  end
-  
 end
 
diff --git a/spec/data_patcher_spec.rb b/spec/data_patcher_spec.rb
index 091677e..d7c4a3b 100644
--- a/spec/data_patcher_spec.rb
+++ b/spec/data_patcher_spec.rb
@@ -3,40 +3,29 @@
 describe DataPatcher do
   
   before(:each) do
-    @existing_item_1 = {
-                :title => "Mastering Data Warehouse Aggregates",
-                :summary => "The first book to provide in-depth coverage of star schema aggregates...",
-                :asin => "0471777099" }
-    @existing_item_2 = {
-                  :title => "The Data Warehouse ETL Toolkit",
-                  :summary => "The single most authoritative guide on the most difficult phase of building a data warehouse",
-                  :asin => "0764567578" }
-    @existing_items = [@existing_item_1, @existing_item_2]
-    Item.delete_all
-    Item.create!(@existing_item_1)
-    Item.create!(@existing_item_2)
-    @patcher = DataPatcher.new
-  end
-  
-  def patcher
-    @patcher
+    load_fixture
+    
+    @patcher = DataPatcher.new(Item, :asin)
+    # pre-load the patcher with all the existing data, so that we can simulate an addition or modification
+    @patcher.analyze_record(@existing_item_1)
+    @patcher.analyze_record(@existing_item_2)
   end
   
   it "provides an addition patch including the key and the attributes" do
-    patcher.analyze_records(:asin, @existing_items)
-    patcher.analyze_record(:asin, { :asin => "123", :title => "Hello", :summary => "The best of hello world" } )
-    patcher.patch.should == {
+    @patcher.analyze_record({ :asin => "123", :title => "Hello", :summary => "The best of hello world" } )
+
+    @patcher.patch.should == {
       :added => [{ :asin => "123", :title => "Hello", :summary => "The best of hello world" }]
     }
   end
   
   it "provides a modification patch including the key and updated attributes" do
-    patcher.analyze_records(:asin, @existing_items)
-    patcher.analyze_record(:asin, { 
+    @patcher.analyze_record( { 
       :asin => "0471777099", # key
       :title => "Mastering Data Warehouse Aggregates (Hard cover)", # changed data
       :summary => "The first book to provide in-depth coverage of star schema aggregates..."}) # unchanged data
-    patcher.patch.should == {
+
+    @patcher.patch.should == {
       :modified => [{ :asin => "0471777099", :title => "Mastering Data Warehouse Aggregates (Hard cover)"}]
     }
   end
diff --git a/spec/migrations/create_items.rb b/spec/migrations/create_items.rb
index b3b7a0f..0127ad9 100644
--- a/spec/migrations/create_items.rb
+++ b/spec/migrations/create_items.rb
@@ -5,10 +5,3 @@
   t.column :asin,    :string, :null => false
   # TODO - add timestamps here ?
 end
-
-Item.create :title => "Mastering Data Warehouse Aggregates",
-            :summary => "tThe first book to provide in-depth coverage of star schema aggregates...",
-            :asin => "0471777099"
-Item.create :title => "The Data Warehouse ETL Toolkit",
-            :summary => "The single most authoritative guide on the most difficult phase of building a data warehouse",
-            :asin => "0764567578"
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index c915b4a..3fe68d1 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -2,6 +2,7 @@
 require 'spec'
 
 $LOAD_PATH.unshift(File.dirname(__FILE__))
+$LOAD_PATH.unshift(File.dirname(__FILE__) + "/../lib")
 
 require 'data_patcher'
 
@@ -28,3 +29,16 @@
   require file.gsub(/\.rb$/, '')
 end
 
+def load_fixture
+  @existing_item_1 = {
+              :title => "Mastering Data Warehouse Aggregates",
+              :summary => "The first book to provide in-depth coverage of star schema aggregates...",
+              :asin => "0471777099" }
+  @existing_item_2 = {
+                :title => "The Data Warehouse ETL Toolkit",
+                :summary => "The single most authoritative guide on the most difficult phase of building a data warehouse",
+                :asin => "0764567578" }
+  Item.delete_all
+  Item.create!(@existing_item_1)
+  Item.create!(@existing_item_2)
+end
\ No newline at end of file