add API to pg for enabling / disabling hstore

3 files changed, 54 insertions, 7 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index cbb6869e66..b2ad4e600d 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -171,6 +171,12 @@ module ActiveRecord
         false
       end
 
+      # Does this adapter support database extensions?  As of this writing
+      # only postgresql does.
+      def supports_extensions?
+        false
+      end
+
       # QUOTING ==================================================
 
       # Returns a bind substitution value given a +column+ and list of current
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 209553b26e..a2b32bf3e2 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -575,11 +575,30 @@ module ActiveRecord
         true
       end
 
+      # Returns true.
+      def supports_extensions?
+        postgresql_version >= 90200
+      end
+
       # Range datatypes weren't introduced until PostgreSQL 9.2
       def supports_ranges?
         postgresql_version >= 90200
       end
 
+      def enable_extension(name)
+        exec_query "CREATE EXTENSION IF NOT EXISTS #{name}"
+      end
+
+      def disable_extension(name)
+        exec_query "DROP EXTENSION IF EXISTS #{name} CASCADE"
+      end
+
+      def extension_enabled?(name)
+        res = exec_query "SELECT EXISTS(SELECT * FROM pg_available_extensions WHERE name = '#{name}' AND installed_version IS NOT NULL)",
+                   'SCHEMA'
+        res.column_types['exists'].type_cast res.rows.first.first
+      end
+
       # Returns the configured supported identifier length supported by PostgreSQL
       def table_alias_length
         @table_alias_length ||= query('SHOW max_identifier_length', 'SCHEMA')[0][0].to_i
diff --git a/activerecord/test/cases/adapters/postgresql/hstore_test.rb b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
index 23bafde17b..9498c829dc 100644
--- a/activerecord/test/cases/adapters/postgresql/hstore_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
@@ -11,15 +11,16 @@ class PostgresqlHstoreTest < ActiveRecord::TestCase
 
   def setup
     @connection = ActiveRecord::Base.connection
-    begin
-      @connection.transaction do
-        @connection.create_table('hstores') do |t|
-          t.hstore 'tags', :default => ''
-        end
-      end
-    rescue ActiveRecord::StatementInvalid
+    unless @connection.extension_enabled?('hstore')
+      @connection.enable_extension 'hstore'
       return skip "do not test on PG without hstore"
     end
+
+    @connection.transaction do
+      @connection.create_table('hstores') do |t|
+        t.hstore 'tags', :default => ''
+      end
+    end
     @column = Hstore.columns.find { |c| c.name == 'tags' }
   end
 
@@ -27,6 +28,27 @@ class PostgresqlHstoreTest < ActiveRecord::TestCase
     @connection.execute 'drop table if exists hstores'
   end
 
+  def test_hstore_enabled
+    assert @connection.extension_enabled?('hstore')
+  end
+
+  def test_disable_hstore
+    if @connection.extension_enabled?('hstore')
+      @connection.disable_extension 'hstore'
+      assert_not @connection.extension_enabled?('hstore')
+    end
+  end
+
+  def test_enable_hstore
+    if @connection.extension_enabled?('hstore')
+      @connection.disable_extension 'hstore'
+    end
+
+    assert_not @connection.extension_enabled?('hstore')
+    @connection.enable_extension 'hstore'
+    assert @connection.extension_enabled?('hstore')
+  end
+
   def test_column
     assert_equal :hstore, @column.type
   end