Added find_last_by dynamic finder [status:committed #762]

Signed-off-by: David Heinemeier Hansson <david@loudthinking.com>

3 files changed, 39 insertions, 5 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 907495a416..0fe9e12549 100755..100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -287,6 +287,7 @@ module ActiveRecord #:nodoc:
   # It's even possible to use all the additional parameters to find. For example, the full interface for <tt>Payment.find_all_by_amount</tt>
   # is actually <tt>Payment.find_all_by_amount(amount, options)</tt>. And the full interface to <tt>Person.find_by_user_name</tt> is
   # actually <tt>Person.find_by_user_name(user_name, options)</tt>. So you could call <tt>Payment.find_all_by_amount(50, :order => "created_on")</tt>.
+  # Also you may call <tt>Payment.find_last_by_amount(amount, options)</tt> returning the last record matching that amount and options.
   #
   # The same dynamic finder style can be used to create the object if it doesn't already exist. This dynamic finder is called with
   # <tt>find_or_create_by_</tt> and will return the object if it already exists and otherwise creates it, then returns it. Protected attributes won't be set unless they are given in a block. For example:
diff --git a/activerecord/lib/active_record/dynamic_finder_match.rb b/activerecord/lib/active_record/dynamic_finder_match.rb
index b105b919f5..f4a5712981 100644
--- a/activerecord/lib/active_record/dynamic_finder_match.rb
+++ b/activerecord/lib/active_record/dynamic_finder_match.rb
@@ -8,7 +8,8 @@ module ActiveRecord
     def initialize(method)
       @finder = :find_initial
       case method.to_s
-      when /^find_(all_by|by)_([_a-zA-Z]\w*)$/
+      when /^find_(all_by|last_by|by)_([_a-zA-Z]\w*)$/
+        @finder = :find_last if $1 == 'last_by'
         @finder = :find_every if $1 == 'all_by'
         names = $2
       when /^find_by_([_a-zA-Z]\w*)\!$/
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index 2ce49ed76f..3eee2056dd 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -197,11 +197,11 @@ class FinderTest < ActiveRecord::TestCase
     first = Topic.find(:first, :conditions => "title = 'The First Topic!'")
     assert_nil(first)
   end
-  
+
   def test_first
     assert_equal topics(:second).title, Topic.first(:conditions => "title = 'The Second Topic of the day'").title
   end
-  
+
   def test_first_failing
     assert_nil Topic.first(:conditions => "title = 'The Second Topic of the day!'")
   end
@@ -418,7 +418,7 @@ class FinderTest < ActiveRecord::TestCase
   def test_named_bind_variables
     assert_equal '1', bind(':a', :a => 1) # ' ruby-mode
     assert_equal '1 1', bind(':a :a', :a => 1)  # ' ruby-mode
-    
+
     assert_nothing_raised { bind("'+00:00'", :foo => "bar") }
 
     assert_kind_of Firm, Company.find(:first, :conditions => ["name = :name", { :name => "37signals" }])
@@ -589,6 +589,38 @@ class FinderTest < ActiveRecord::TestCase
     assert_nil Topic.find_by_title_and_author_name("The First Topic", "Mary")
   end
 
+  def test_find_last_by_one_attribute
+    assert_equal Topic.last, Topic.find_last_by_title(Topic.last.title)
+    assert_nil Topic.find_last_by_title("A title with no matches")
+  end
+
+  def test_find_last_by_one_attribute_caches_dynamic_finder
+    # ensure this test can run independently of order
+    class << Topic; self; end.send(:remove_method, :find_last_by_title) if Topic.public_methods.any? { |m| m.to_s == 'find_last_by_title' }
+    assert !Topic.public_methods.any? { |m| m.to_s == 'find_last_by_title' }
+    t = Topic.find_last_by_title(Topic.last)
+    assert Topic.public_methods.any? { |m| m.to_s == 'find_last_by_title' }
+  end
+
+  def test_find_last_by_invalid_method_syntax
+    assert_raises(NoMethodError) { Topic.fail_to_find_last_by_title("The First Topic") }
+    assert_raises(NoMethodError) { Topic.find_last_by_title?("The First Topic") }
+  end
+
+  def test_find_last_by_one_attribute_with_several_options
+    assert_equal accounts(:signals37), Account.find_last_by_credit_limit(50, :order => 'id DESC', :conditions => ['id != ?', 3])
+  end
+
+  def test_find_last_by_one_missing_attribute
+    assert_raises(NoMethodError) { Topic.find_last_by_undertitle("The Last Topic!") }
+  end
+
+  def test_find_last_by_two_attributes
+    topic = Topic.last
+    assert_equal topic, Topic.find_last_by_title_and_author_name(topic.title, topic.author_name)
+    assert_nil Topic.find_last_by_title_and_author_name(topic.title, "Anonymous")
+  end
+
   def test_find_all_by_one_attribute
     topics = Topic.find_all_by_content("Have a nice day")
     assert_equal 2, topics.size
@@ -782,7 +814,7 @@ class FinderTest < ActiveRecord::TestCase
     assert c.valid?
     assert !c.new_record?
   end
-  
+
   def test_dynamic_find_or_initialize_from_one_attribute_caches_method
     class << Company; self; end.send(:remove_method, :find_or_initialize_by_name) if Company.public_methods.any? { |m| m.to_s == 'find_or_initialize_by_name' }
     assert !Company.public_methods.any? { |m| m.to_s == 'find_or_initialize_by_name' }