Added AbstractAdapter#select_value and AbstractAdapter#select_values as convenience methods for selecting single values, instead of hashes, of the first column in a SELECT #2283

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2323 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

4 files changed, 28 insertions, 10 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 73c69a91d1..03123758ef 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -464,13 +464,7 @@ module ActiveRecord #:nodoc:
       #   Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
       def count_by_sql(sql)
         sql = sanitize_conditions(sql)
-        rows = connection.select_one(sql, "#{name} Count")
-
-        if !rows.nil? and count = rows.values.first
-          count.to_i
-        else
-          0
-        end
+        connection.select_value(sql, "#{name} Count").to_i
       end
 
       # Increments the specified counter by one. So <tt>DiscussionBoard.increment_counter("post_count",
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index a1a71afb5b..fed51fea18 100755
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -275,6 +275,19 @@ module ActiveRecord
       # Returns a record hash with the column names as a keys and fields as values.
       def select_one(sql, name = nil) end
 
+      # Returns a single value from a record
+      def select_value(sql, name = nil)
+        result = select_one(sql, name)
+        result.nil? ? nil : result.values.first
+      end
+
+      # Returns an array of the values of the first column in a select:
+      #   select_values("SELECT id FROM companies LIMIT 3") => [1,2,3]
+      def select_values(sql, name = nil)
+        result = select_all(sql, name)
+        result.map{ |v| v.values.first }
+      end
+
       # Returns an array of table names for the current database.
       # def tables(name = nil) end
 
diff --git a/activerecord/lib/active_record/transactions.rb b/activerecord/lib/active_record/transactions.rb
index de2937a96d..e9a612495c 100644
--- a/activerecord/lib/active_record/transactions.rb
+++ b/activerecord/lib/active_record/transactions.rb
@@ -81,9 +81,7 @@ module ActiveRecord
     # Tribute: Object-level transactions are implemented by Transaction::Simple by Austin Ziegler.
     module ClassMethods
       def transaction(*objects, &block)
-        previous_handler = trap('TERM') do
-          raise TransactionError, "Transaction aborted"
-        end
+        previous_handler = trap('TERM') { raise TransactionError, "Transaction aborted" }
         lock_mutex
         
         begin
diff --git a/activerecord/test/finder_test.rb b/activerecord/test/finder_test.rb
index 2f23503ce1..8fc89f3808 100644
--- a/activerecord/test/finder_test.rb
+++ b/activerecord/test/finder_test.rb
@@ -311,6 +311,19 @@ class FinderTest < Test::Unit::TestCase
     assert developer_names.include?('Jamis')
   end
 
+  def test_select_value
+    assert_equal "37signals", Company.connection.select_value("SELECT name FROM companies WHERE id = 1")
+    assert_nil Company.connection.select_value("SELECT name FROM companies WHERE id = -1")
+    # make sure we didn't break count...
+    assert_equal 0, Company.count_by_sql("SELECT COUNT(*) FROM companies WHERE name = 'Halliburton'")
+    assert_equal 1, Company.count_by_sql("SELECT COUNT(*) FROM companies WHERE name = '37signals'")
+  end
+
+  def test_select_values
+    assert_equal ["1","2","3"], Company.connection.select_values("SELECT id FROM companies ORDER BY id LIMIT 3")
+    assert_equal ["37signals","Summit","Microsoft"], Company.connection.select_values("SELECT name FROM companies ORDER BY id LIMIT 3")
+  end
+
   protected
     def bind(statement, *vars)
       if vars.first.is_a?(Hash)