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Diffstat (limited to 'guides/source/4_0_release_notes.md')
| -rw-r--r-- | guides/source/4_0_release_notes.md | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/guides/source/4_0_release_notes.md b/guides/source/4_0_release_notes.md index dd57787111..55ac4bca87 100644 --- a/guides/source/4_0_release_notes.md +++ b/guides/source/4_0_release_notes.md @@ -165,6 +165,19 @@ Please refer to the [Changelog](https://github.com/rails/rails/blob/master/railt ### Notable changes +* Improve ways to write `change` migrations, making the old `up` & `down` methods no longer necessary. + + * The methods `drop_table` and `remove_column` are now reversible, as long as the necessary information is given. + The method `remove_column` used to accept multiple column names; instead use `remove_columns` (which is not revertible). + The method `change_table` is also reversible, as long as its block doesn't call `remove`, `change` or `change_default` + + * New method `reversible` makes it possible to specify code to be run when migrating up or down. + See the [Guide on Migration](https://github.com/rails/rails/blob/master/guides/source/migrations.md#using-the-reversible-method) + + * New method `revert` will revert a whole migration or the given block. + If migrating down, the given migration / block is run normally. + See the [Guide on Migration](https://github.com/rails/rails/blob/master/guides/source/migrations.md#reverting-previous-migrations) + * Adds some metadata columns to `schema_migrations` table. * `migrated_at` |