lib/strong_migrations/migration.rb in strong_migrations-0.2.0 vs lib/strong_migrations/migration.rb in strong_migrations-0.2.1

@@ -26,24 +26,36 @@
           raise_error :rename_table
         when :rename_column
           raise_error :rename_column
         when :add_index
           columns = args[1]
-          if columns.is_a?(Array) && columns.size > 3
+          options = args[2] || {}
+          if columns.is_a?(Array) && columns.size > 3 && !options[:unique]
             raise_error :add_index_columns
           end
-          options = args[2] || {}
           if postgresql? && options[:algorithm] != :concurrently && !@new_tables.to_a.include?(args[0].to_s)
             raise_error :add_index
           end
         when :add_column
           type = args[2]
           options = args[3] || {}
           raise_error :add_column_default unless options[:default].nil?
-          raise_error :add_column_json if type.to_s == "json"
+          if type.to_s == "json" && postgresql?
+            if postgresql_version >= 90400
+              raise_error :add_column_json
+            else
+              raise_error :add_column_json_legacy
+            end
+          end
         when :change_column
-          raise_error :change_column
+          safe = false
+          # assume Postgres 9.1+ since previous versions are EOL
+          if postgresql? && args[2].to_s == "text"
+            column = connection.columns(args[0]).find { |c| c.name.to_s == args[1].to_s }
+            safe = column && column.type == :string
+          end
+          raise_error :change_column unless safe
         when :create_table
           options = args[1] || {}
           raise_error :create_table if options[:force]
         when :add_reference
           options = args[2] || {}
@@ -71,9 +83,13 @@
 
     private
 
     def postgresql?
       %w(PostgreSQL PostGIS).include?(connection.adapter_name)
+    end
+
+    def postgresql_version
+      @postgresql_version ||= connection.execute("SHOW server_version_num").first["server_version_num"].to_i
     end
 
     def version_safe?
       version && version <= StrongMigrations.start_after
     end