8 files changed, 52 insertions, 36 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index aa84dacf07..6f0b5bfce6 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -580,19 +580,6 @@
     a URI that specifies the connection configuration.  For example:
         ActiveRecord::Base.establish_connection 'postgres://localhost/foo'
 
-*   Active Record's dynamic finder will now raise the error if you passing in less number of arguments than what you call in method signature.
-
-    So if you were doing this and expecting the second argument to be nil:
-
-        User.find_by_username_and_group("sikachu")
-
-    You'll now get `ArgumentError: wrong number of arguments (1 for 2).` You'll then have to do this:
-
-        User.find_by_username_and_group("sikachu", nil)
-
-    *Prem Sichanugrist*
-
-
 ## Rails 3.1.0 (August 30, 2011) ##
 
 *   Add a proxy_association method to association proxies, which can be called by association
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index fc3906d395..189985b671 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -304,21 +304,22 @@ module ActiveRecord #:nodoc:
   #   (or a bad spelling of an existing one).
   # * AssociationTypeMismatch - The object assigned to the association wasn't of the type
   #   specified in the association definition.
-  # * SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter.
+  # * AttributeAssignmentError - An error occurred while doing a mass assignment through the
+  #   <tt>attributes=</tt> method.
+  #   You can inspect the +attribute+ property of the exception object to determine which attribute
+  #   triggered the error.
   # * ConnectionNotEstablished - No connection has been established. Use <tt>establish_connection</tt>
   #   before querying.
-  # * RecordNotFound - No record responded to the +find+ method. Either the row with the given ID doesn't exist
-  #   or the row didn't meet the additional restrictions. Some +find+ calls do not raise this exception to signal
-  #   nothing was found, please check its documentation for further details.
-  # * StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message.
   # * MultiparameterAssignmentErrors - Collection of errors that occurred during a mass assignment using the
   #   <tt>attributes=</tt> method. The +errors+ property of this exception contains an array of
   #   AttributeAssignmentError
   #   objects that should be inspected to determine which attributes triggered the errors.
-  # * AttributeAssignmentError - An error occurred while doing a mass assignment through the
-  #   <tt>attributes=</tt> method.
-  #   You can inspect the +attribute+ property of the exception object to determine which attribute
-  #   triggered the error.
+  # * RecordInvalid - raised by save! and create! when the record is invalid.
+  # * RecordNotFound - No record responded to the +find+ method. Either the row with the given ID doesn't exist
+  #   or the row didn't meet the additional restrictions. Some +find+ calls do not raise this exception to signal
+  #   nothing was found, please check its documentation for further details.
+  # * SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter.
+  # * StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message.
   #
   # *Note*: The attributes listed are class-level attributes (accessible from both the class and instance level).
   # So it's possible to assign a logger to the class through <tt>Base.logger=</tt> which will then be used by all
diff --git a/activerecord/lib/active_record/explain.rb b/activerecord/lib/active_record/explain.rb
index 01cacf6153..313fdb3487 100644
--- a/activerecord/lib/active_record/explain.rb
+++ b/activerecord/lib/active_record/explain.rb
@@ -70,7 +70,7 @@ module ActiveRecord
     # the threshold is set to 0.
     #
     # As the name of the method suggests this only applies to automatic
-    # EXPLAINs, manual calls to +ActiveRecord::Relation#explain+ run.
+    # EXPLAINs, manual calls to <tt>ActiveRecord::Relation#explain</tt> run.
     def silence_auto_explain
       current = Thread.current
       original, current[:available_queries_for_explain] = current[:available_queries_for_explain], false
diff --git a/activerecord/lib/active_record/querying.rb b/activerecord/lib/active_record/querying.rb
index 95565b503a..29b8b2fb73 100644
--- a/activerecord/lib/active_record/querying.rb
+++ b/activerecord/lib/active_record/querying.rb
@@ -11,7 +11,7 @@ module ActiveRecord
     delegate :select, :group, :order, :except, :reorder, :limit, :offset, :joins,
              :where, :preload, :eager_load, :includes, :from, :lock, :readonly,
              :having, :create_with, :uniq, :references, :none, :to => :scoped
-    delegate :count, :average, :minimum, :maximum, :sum, :calculate, :pluck, :to => :scoped
+    delegate :count, :average, :minimum, :maximum, :sum, :calculate, :pluck, :ids, :to => :scoped
 
     # Executes a custom SQL query against your database and returns all the results. The results will
     # be returned as an array with columns requested encapsulated as attributes of the model you call
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index db894c8aa9..f388b75c05 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -139,6 +139,16 @@ module ActiveRecord
       end
     end
 
+    # Pluck all the ID's for the relation using the table's primary key
+    #
+    # Examples:
+    #
+    #   Person.ids # SELECT people.id FROM people
+    #   Person.joins(:companies).ids # SELECT people.id FROM PEOPLE INNER JOIN companies ON companies.person_id = people.id
+    def ids
+      pluck primary_key
+    end
+
     private
 
     def perform_calculation(operation, column_name, options = {})
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 416b55f5c5..1ceb1949a4 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -217,8 +217,11 @@ module ActiveRecord
       if match.bang? && result.blank?
         raise RecordNotFound, "Couldn't find #{@klass.name} with #{conditions.to_a.collect {|p| p.join(' = ')}.join(', ')}"
       else
-        yield(result) if block_given?
-        result
+        if block_given? && result
+          yield(result)
+        else
+          result
+        end
       end
     end
 
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 8a4ce5e963..35e0045e4c 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -125,20 +125,13 @@ class BasicsTest < ActiveRecord::TestCase
 
   unless current_adapter?(:PostgreSQLAdapter,:OracleAdapter,:SQLServerAdapter)
     def test_limit_with_comma
-      assert_nothing_raised do
-        Topic.limit("1,2").all
-      end
+      assert Topic.limit("1,2").all
     end
   end
 
   def test_limit_without_comma
-    assert_nothing_raised do
-      assert_equal 1, Topic.limit("1").all.length
-    end
-
-    assert_nothing_raised do
-      assert_equal 1, Topic.limit(1).all.length
-    end
+    assert_equal 1, Topic.limit("1").all.length
+    assert_equal 1, Topic.limit(1).all.length
   end
 
   def test_invalid_limit
@@ -175,6 +168,24 @@ class BasicsTest < ActiveRecord::TestCase
     assert Topic.table_exists?
   end
 
+  def test_finder_block
+    t = Topic.first
+    found = nil
+    Topic.find_by_id(t.id) { |f| found = f }
+    assert_equal t, found
+  end
+
+  def test_finder_block_nothing_found
+    bad_id = Topic.maximum(:id) + 1
+    assert_nil Topic.find_by_id(bad_id) { |f| raise }
+  end
+
+  def test_find_returns_block_value
+    t = Topic.first
+    x = Topic.find_by_id(t.id) { |f| "hi mom!" }
+    assert_equal "hi mom!", x
+  end
+
   def test_preserving_date_objects
     if current_adapter?(:SybaseAdapter)
       # Sybase ctlib does not (yet?) support the date type; use datetime instead.
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index 2e566ff873..e096585f62 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -465,4 +465,8 @@ class CalculationsTest < ActiveRecord::TestCase
     Company.create!(:name => "test", :contracts => [Contract.new(:developer_id => 7)])
     assert_equal [7], Company.joins(:contracts).pluck(:developer_id)
   end
+
+  def test_plucks_with_ids
+    assert_equal Company.all.map(&:id).sort, Company.ids.sort
+  end
 end