From f6f416c58e805604390314e2e8e5ecf6a0a78b4f Mon Sep 17 00:00:00 2001
From: Pratik Naik <pratiknaik@gmail.com>
Date: Sun, 27 Dec 2009 03:25:29 +0530
Subject: Add find_by_* and find_all_by_* finders to ActiveRecord::Relation

---
 activerecord/lib/active_record/relation.rb | 14 ++++++++++++
 activerecord/test/cases/relations_test.rb  | 34 +++++++++++++++++++++++++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index b6800b07b7..f9ca6cbbd2 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -136,6 +136,20 @@ module ActiveRecord
         @relation.send(method, *args, &block)
       elsif Array.method_defined?(method)
         to_a.send(method, *args, &block)
+      elsif match = DynamicFinderMatch.match(method)
+        attributes = match.attribute_names
+        super unless @klass.send(:all_attributes_exists?, attributes)
+
+        if match.finder?
+          conditions = attributes.inject({}) {|h, a| h[a] = args[attributes.index(a)]; h}
+          result = where(conditions).send(match.finder)
+
+          if match.bang? && result.blank?
+            raise RecordNotFound, "Couldn't find #{@klass.name} with #{conditions.to_a.collect {|p| p.join(' = ')}.join(', ')}"
+          else
+            result
+          end
+        end
       else
         super
       end
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index e05da58ae6..f94402f57e 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1,4 +1,6 @@
 require "cases/helper"
+require 'models/tag'
+require 'models/tagging'
 require 'models/post'
 require 'models/topic'
 require 'models/comment'
@@ -10,7 +12,8 @@ require 'models/developer'
 require 'models/company'
 
 class RelationTest < ActiveRecord::TestCase
-  fixtures :authors, :topics, :entrants, :developers, :companies, :developers_projects, :accounts, :categories, :categorizations, :posts, :comments
+  fixtures :authors, :topics, :entrants, :developers, :companies, :developers_projects, :accounts, :categories, :categorizations, :posts, :comments,
+    :taggings
 
   def test_scoped
     topics = Topic.scoped
@@ -222,5 +225,34 @@ class RelationTest < ActiveRecord::TestCase
     post = posts.find { |p| p.id == 1 }
     assert_equal Post.find(1).last_comment, post.last_comment
   end
+
+  def test_dynamic_find_by_attributes
+    david = authors(:david)
+    author = Author.preload(:taggings).find_by_id(david.id)
+    expected_taggings = taggings(:welcome_general, :thinking_general)
+
+    assert_no_queries do
+      assert_equal expected_taggings, author.taggings.uniq.sort_by { |t| t.id }
+    end
+
+    authors = Author.scoped
+    assert_equal david, authors.find_by_id_and_name(david.id, david.name)
+    assert_equal david, authors.find_by_id_and_name!(david.id, david.name)
+  end
+
+  def test_dynamic_find_by_attributes_bang
+    author = Author.scoped.find_by_id!(authors(:david).id)
+    assert_equal "David", author.name
+
+    assert_raises(ActiveRecord::RecordNotFound) { Author.scoped.find_by_id_and_name!('invalid', 'wt') }
+  end
+
+  def test_dynamic_find_all_by_attributes
+    authors = Author.scoped
+
+    davids = authors.find_all_by_name('David')
+    assert_kind_of Array, davids
+    assert_equal [authors(:david)], davids
+  end
 end
 
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