Fix postgre alter null. (#142)

aerich/__init__.py

@@ -1 +1 @@
-__version__ = "0.5.2"
+__version__ = "0.5.3"

aerich/ddl/__init__.py

@@ -227,10 +227,10 @@ class BaseDDL:
         )
 
     def alter_column_null(self, model: "Type[Model]", field_describe: dict):
-        raise NotImplementedError
+        return self.modify_column(model, field_describe)
 
     def set_comment(self, model: "Type[Model]", field_describe: dict):
-        raise NotImplementedError
+        return self.modify_column(model, field_describe)
 
     def rename_table(self, model: "Type[Model]", old_table_name: str, new_table_name: str):
         db_table = model._meta.db_table

aerich/ddl/mysql/__init__.py

@@ -1,10 +1,6 @@
-from typing import Type
-
-from tortoise import Model
 from tortoise.backends.mysql.schema_generator import MySQLSchemaGenerator
 
 from aerich.ddl import BaseDDL
-from aerich.exceptions import NotSupportError
 
 
 class MysqlDDL(BaseDDL):
@@ -29,9 +25,3 @@ class MysqlDDL(BaseDDL):
     _M2M_TABLE_TEMPLATE = "CREATE TABLE `{table_name}` (`{backward_key}` {backward_type} NOT NULL REFERENCES `{backward_table}` (`{backward_field}`) ON DELETE CASCADE,`{forward_key}` {forward_type} NOT NULL REFERENCES `{forward_table}` (`{forward_field}`) ON DELETE CASCADE){extra}{comment}"
     _MODIFY_COLUMN_TEMPLATE = "ALTER TABLE `{table_name}` MODIFY COLUMN {column}"
     _RENAME_TABLE_TEMPLATE = "ALTER TABLE `{old_table_name}` RENAME TO `{new_table_name}`"
-
-    def alter_column_null(self, model: "Type[Model]", field_describe: dict):
-        raise NotSupportError("Alter column null is unsupported in MySQL.")
-
-    def set_comment(self, model: "Type[Model]", field_describe: dict):
-        raise NotSupportError("Alter column comment is unsupported in MySQL.")

aerich/migrate.py

@@ -399,6 +399,9 @@ class Migrate:
                         elif option == "unique":
                             # because indexed include it
                             pass
+                        elif option == "nullable":
+                            # change nullable
+                            cls._add_operator(cls._alter_null(model, new_data_field), upgrade)
                         else:
                             # modify column
                             cls._add_operator(