Merge pull request #769 from aidanharan/readonly-mode

Rails 6: Add ability to block writes to a database

Author: wpolicarpo

lib/active_record/connection_adapters/sqlserver/database_statements.rb

@@ -2,8 +2,18 @@ module ActiveRecord
   module ConnectionAdapters
     module SQLServer
       module DatabaseStatements
+        READ_QUERY = ActiveRecord::ConnectionAdapters::AbstractAdapter.build_read_query_regexp(:begin, :commit, :dbcc, :explain, :save, :select, :set, :rollback) # :nodoc:
+        private_constant :READ_QUERY
+
+        def write_query?(sql) # :nodoc:
+          !READ_QUERY.match?(sql)
+        end
 
         def execute(sql, name = nil)
+          if preventing_writes? && write_query?(sql)
+            raise ActiveRecord::ReadOnlyError, "Write query attempted while in readonly mode: #{sql}"
+          end
+
           if id_insert_table_name = query_requires_identity_insert?(sql)
             with_identity_insert_enabled(id_insert_table_name) { do_execute(sql, name) }
           else
@@ -12,6 +22,10 @@ def execute(sql, name = nil)
         end
 
         def exec_query(sql, name = 'SQL', binds = [], prepare: false)
+          if preventing_writes? && write_query?(sql)
+            raise ActiveRecord::ReadOnlyError, "Write query attempted while in readonly mode: #{sql}"
+          end
+
           sp_executesql(sql, name, binds, prepare: prepare)
         end
 

test/cases/adapter_test_sqlserver.rb

@@ -13,7 +13,7 @@ class AdapterTestSQLServer < ActiveRecord::TestCase
   let(:basic_update_sql) { "UPDATE [customers] SET [address_street] = NULL WHERE [id] = 2" }
   let(:basic_select_sql) { "SELECT * FROM [customers] WHERE ([customers].[id] = 1)" }
 
-  it 'has basic and non-senstive information in the adpaters inspect method' do
+  it 'has basic and non-sensitive information in the adapters inspect method' do
     string = connection.inspect
     _(string).must_match %r{ActiveRecord::ConnectionAdapters::SQLServerAdapter}
     _(string).must_match %r{version\: \d.\d}
@@ -429,5 +429,48 @@ class AdapterTestSQLServer < ActiveRecord::TestCase
     end
   end
 
+  describe 'block writes to a database' do
+    def setup
+      @conn = ActiveRecord::Base.connection
+      @connection_handler = ActiveRecord::Base.connection_handler
+    end
+
+    def test_errors_when_an_insert_query_is_called_while_preventing_writes
+      assert_raises(ActiveRecord::ReadOnlyError) do
+        @connection_handler.while_preventing_writes do
+          @conn.insert("INSERT INTO [subscribers] ([nick]) VALUES ('aido')")
+        end
+      end
+    end
+
+    def test_errors_when_an_update_query_is_called_while_preventing_writes
+      @conn.insert("INSERT INTO [subscribers] ([nick]) VALUES ('aido')")
+
+      assert_raises(ActiveRecord::ReadOnlyError) do
+        @connection_handler.while_preventing_writes do
+          @conn.update("UPDATE [subscribers] SET [subscribers].[name] = 'Aidan' WHERE [subscribers].[nick] = 'aido'")
+        end
+      end
+    end
+
+    def test_errors_when_a_delete_query_is_called_while_preventing_writes
+      @conn.execute("INSERT INTO [subscribers] ([nick]) VALUES ('aido')")
+
+      assert_raises(ActiveRecord::ReadOnlyError) do
+        @connection_handler.while_preventing_writes do
+          @conn.execute("DELETE FROM [subscribers] WHERE [subscribers].[nick] = 'aido'")
+        end
+      end
+    end
+
+    def test_doesnt_error_when_a_select_query_is_called_while_preventing_writes
+      @conn.execute("INSERT INTO [subscribers] ([nick]) VALUES ('aido')")
+
+      @connection_handler.while_preventing_writes do
+        assert_equal 1, @conn.execute("SELECT * FROM [subscribers] WHERE [subscribers].[nick] = 'aido'")
+      end
+    end
+  end
+
 end