Merge pull request #31230 from dinahshi/postgresql_extract_sql

Extract sql fragment generators from PostgreSQL adapter

4 files changed, 88 insertions, 59 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 09ccf0c193..fac9e1cca2 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -600,7 +600,7 @@ module ActiveRecord
       # to provide these in a migration's +change+ method so it can be reverted.
       # In that case, +type+ and +options+ will be used by #add_column.
       def remove_column(table_name, column_name, type = nil, options = {})
-        execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{quote_column_name(column_name)}"
+        execute "ALTER TABLE #{quote_table_name(table_name)} #{remove_column_for_alter(table_name, column_name, type, options)}"
       end
 
       # Changes the column's definition according to the new options.
@@ -1365,6 +1365,20 @@ module ActiveRecord
           options.is_a?(Hash) && options.key?(:name) && options.except(:name, :algorithm).empty?
         end
 
+        def add_column_for_alter(table_name, column_name, type, options = {})
+          td = create_table_definition(table_name)
+          cd = td.new_column_definition(column_name, type, options)
+          schema_creation.accept(AddColumnDefinition.new(cd))
+        end
+
+        def remove_column_for_alter(table_name, column_name, type = nil, options = {})
+          "DROP COLUMN #{quote_column_name(column_name)}"
+        end
+
+        def remove_columns_for_alter(table_name, *column_names)
+          column_names.map { |column_name| remove_column_for_alter(table_name, column_name) }
+        end
+
         def insert_versions_sql(versions)
           sm_table = quote_table_name(ActiveRecord::SchemaMigration.table_name)
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index ede8a9c1e2..143dc6d08d 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -299,7 +299,7 @@ module ActiveRecord
       def bulk_change_table(table_name, operations) #:nodoc:
         sqls = operations.flat_map do |command, args|
           table, arguments = args.shift, args
-          method = :"#{command}_sql"
+          method = :"#{command}_for_alter"
 
           if respond_to?(method, true)
             send(method, table, *arguments)
@@ -372,11 +372,11 @@ module ActiveRecord
       end
 
       def change_column(table_name, column_name, type, options = {}) #:nodoc:
-        execute("ALTER TABLE #{quote_table_name(table_name)} #{change_column_sql(table_name, column_name, type, options)}")
+        execute("ALTER TABLE #{quote_table_name(table_name)} #{change_column_for_alter(table_name, column_name, type, options)}")
       end
 
       def rename_column(table_name, column_name, new_column_name) #:nodoc:
-        execute("ALTER TABLE #{quote_table_name(table_name)} #{rename_column_sql(table_name, column_name, new_column_name)}")
+        execute("ALTER TABLE #{quote_table_name(table_name)} #{rename_column_for_alter(table_name, column_name, new_column_name)}")
         rename_column_indexes(table_name, column_name, new_column_name)
       end
 
@@ -671,13 +671,7 @@ module ActiveRecord
           end
         end
 
-        def add_column_sql(table_name, column_name, type, options = {})
-          td = create_table_definition(table_name)
-          cd = td.new_column_definition(column_name, type, options)
-          schema_creation.accept(AddColumnDefinition.new(cd))
-        end
-
-        def change_column_sql(table_name, column_name, type, options = {})
+        def change_column_for_alter(table_name, column_name, type, options = {})
           column = column_for(table_name, column_name)
           type ||= column.sql_type
 
@@ -698,7 +692,7 @@ module ActiveRecord
           schema_creation.accept(ChangeColumnDefinition.new(cd, column.name))
         end
 
-        def rename_column_sql(table_name, column_name, new_column_name)
+        def rename_column_for_alter(table_name, column_name, new_column_name)
           column  = column_for(table_name, column_name)
           options = {
             default: column.default,
@@ -712,31 +706,23 @@ module ActiveRecord
           schema_creation.accept(ChangeColumnDefinition.new(cd, column.name))
         end
 
-        def remove_column_sql(table_name, column_name, type = nil, options = {})
-          "DROP #{quote_column_name(column_name)}"
-        end
-
-        def remove_columns_sql(table_name, *column_names)
-          column_names.map { |column_name| remove_column_sql(table_name, column_name) }
-        end
-
-        def add_index_sql(table_name, column_name, options = {})
+        def add_index_for_alter(table_name, column_name, options = {})
           index_name, index_type, index_columns, _, index_algorithm, index_using = add_index_options(table_name, column_name, options)
           index_algorithm[0, 0] = ", " if index_algorithm.present?
           "ADD #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})#{index_algorithm}"
         end
 
-        def remove_index_sql(table_name, options = {})
+        def remove_index_for_alter(table_name, options = {})
           index_name = index_name_for_remove(table_name, options)
           "DROP INDEX #{quote_column_name(index_name)}"
         end
 
-        def add_timestamps_sql(table_name, options = {})
-          [add_column_sql(table_name, :created_at, :datetime, options), add_column_sql(table_name, :updated_at, :datetime, options)]
+        def add_timestamps_for_alter(table_name, options = {})
+          [add_column_for_alter(table_name, :created_at, :datetime, options), add_column_for_alter(table_name, :updated_at, :datetime, options)]
         end
 
-        def remove_timestamps_sql(table_name, options = {})
-          [remove_column_sql(table_name, :updated_at), remove_column_sql(table_name, :created_at)]
+        def remove_timestamps_for_alter(table_name, options = {})
+          [remove_column_for_alter(table_name, :updated_at), remove_column_for_alter(table_name, :created_at)]
         end
 
         # MySQL is too stupid to create a temporary table for use subquery, so we have
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index af13a9e16f..64f08e0ee1 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -399,51 +399,24 @@ module ActiveRecord
         end
 
         def change_column(table_name, column_name, type, options = {}) #:nodoc:
-          clear_cache!
           quoted_table_name = quote_table_name(table_name)
-          quoted_column_name = quote_column_name(column_name)
-          sql_type = type_to_sql(type, options)
-          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}".dup
-          if options[:collation]
-            sql << " COLLATE \"#{options[:collation]}\""
-          end
-          if options[:using]
-            sql << " USING #{options[:using]}"
-          elsif options[:cast_as]
-            cast_as_type = type_to_sql(options[:cast_as], options)
-            sql << " USING CAST(#{quoted_column_name} AS #{cast_as_type})"
-          end
-          execute sql
-
-          change_column_default(table_name, column_name, options[:default]) if options.key?(:default)
-          change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
-          change_column_comment(table_name, column_name, options[:comment]) if options.key?(:comment)
+          sqls, procs = change_column_for_alter(table_name, column_name, type, options)
+          execute "ALTER TABLE #{quoted_table_name} #{sqls.join(", ")}"
+          procs.each(&:call)
         end
 
         # Changes the default value of a table column.
         def change_column_default(table_name, column_name, default_or_changes) # :nodoc:
-          clear_cache!
-          column = column_for(table_name, column_name)
-          return unless column
-
-          default = extract_new_default_value(default_or_changes)
-          alter_column_query = "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} %s"
-          if default.nil?
-            # <tt>DEFAULT NULL</tt> results in the same behavior as <tt>DROP DEFAULT</tt>. However, PostgreSQL will
-            # cast the default to the columns type, which leaves us with a default like "default NULL::character varying".
-            execute alter_column_query % "DROP DEFAULT"
-          else
-            execute alter_column_query % "SET DEFAULT #{quote_default_expression(default, column)}"
-          end
+          execute "ALTER TABLE #{quote_table_name(table_name)} #{change_column_default_for_alter(table_name, column_name, default_or_changes)}"
         end
 
         def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
           clear_cache!
           unless null || default.nil?
             column = column_for(table_name, column_name)
-            execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote_default_expression(default, column)} WHERE #{quote_column_name(column_name)} IS NULL") if column
+            execute "UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote_default_expression(default, column)} WHERE #{quote_column_name(column_name)} IS NULL" if column
           end
-          execute("ALTER TABLE #{quote_table_name(table_name)} ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL")
+          execute "ALTER TABLE #{quote_table_name(table_name)} #{change_column_null_for_alter(table_name, column_name, null, default)}"
         end
 
         # Adds comment for given table column or drops it if +comment+ is a +nil+
@@ -679,6 +652,53 @@ module ActiveRecord
             end
           end
 
+          def change_column_for_alter(table_name, column_name, type, options = {})
+            clear_cache!
+            quoted_column_name = quote_column_name(column_name)
+            sql_type = type_to_sql(type, options)
+            sql = "ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}".dup
+            if options[:collation]
+              sql << " COLLATE \"#{options[:collation]}\""
+            end
+            if options[:using]
+              sql << " USING #{options[:using]}"
+            elsif options[:cast_as]
+              cast_as_type = type_to_sql(options[:cast_as], options)
+              sql << " USING CAST(#{quoted_column_name} AS #{cast_as_type})"
+            end
+
+            sqls = [sql]
+            procs = []
+            sqls << change_column_default_for_alter(table_name, column_name, options[:default]) if options.key?(:default)
+            sqls << change_column_null_for_alter(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
+            procs << Proc.new { change_column_comment(table_name, column_name, options[:comment]) } if options.key?(:comment)
+
+            [sqls, procs]
+          end
+
+
+          # Changes the default value of a table column.
+          def change_column_default_for_alter(table_name, column_name, default_or_changes) # :nodoc:
+            clear_cache!
+            column = column_for(table_name, column_name)
+            return unless column
+
+            default = extract_new_default_value(default_or_changes)
+            alter_column_query = "ALTER COLUMN #{quote_column_name(column_name)} %s"
+            if default.nil?
+              # <tt>DEFAULT NULL</tt> results in the same behavior as <tt>DROP DEFAULT</tt>. However, PostgreSQL will
+              # cast the default to the columns type, which leaves us with a default like "default NULL::character varying".
+              alter_column_query % "DROP DEFAULT"
+            else
+              alter_column_query % "SET DEFAULT #{quote_default_expression(default, column)}"
+            end
+          end
+
+          def change_column_null_for_alter(table_name, column_name, null, default = nil) #:nodoc:
+            clear_cache!
+            "ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL"
+          end
+
           def data_source_sql(name = nil, type: nil)
             scope = quoted_scope(name, type: type)
             scope[:type] ||= "'r','v','m'" # (r)elation/table, (v)iew, (m)aterialized view
diff --git a/activerecord/lib/active_record/migration/compatibility.rb b/activerecord/lib/active_record/migration/compatibility.rb
index c979aaf0a0..da307c1723 100644
--- a/activerecord/lib/active_record/migration/compatibility.rb
+++ b/activerecord/lib/active_record/migration/compatibility.rb
@@ -16,6 +16,15 @@ module ActiveRecord
       V5_2 = Current
 
       class V5_1 < V5_2
+        if adapter_name == "PostgreSQL"
+          def change_column(table_name, column_name, type, options = {})
+            unless options[:null] || options[:default].nil?
+              column = connection.send(:column_for, table_name, column_name)
+              connection.execute("UPDATE #{connection.quote_table_name(table_name)} SET #{connection.quote_column_name(column_name)}=#{connection.quote_default_expression(options[:default], column)} WHERE #{connection.quote_column_name(column_name)} IS NULL") if column
+            end
+            connection.change_column(table_name, column_name, type, options)
+          end
+        end
       end
 
       class V5_0 < V5_1