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Diffstat (limited to 'guides/source/active_record_migrations.md')
| -rw-r--r-- | guides/source/active_record_migrations.md | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/guides/source/active_record_migrations.md b/guides/source/active_record_migrations.md index 7a994cc5de..ad069a112e 100644 --- a/guides/source/active_record_migrations.md +++ b/guides/source/active_record_migrations.md @@ -475,7 +475,8 @@ column names can not be derived from the table names, you can use the `:column` and `:primary_key` options. Rails will generate a name for every foreign key starting with -`fk_rails_` followed by 10 random characters. +`fk_rails_` followed by 10 character which is deterministically +generated from the `from_table` and `column`. There is a `:name` option to specify a different name if needed. NOTE: Active Record only supports single column foreign keys. `execute` and @@ -554,7 +555,7 @@ or write the `up` and `down` methods instead of using the `change` method. Complex migrations may require processing that Active Record doesn't know how to reverse. You can use `reversible` to specify what to do when running a -migration what else to do when reverting it. For example: +migration and what else to do when reverting it. For example: ```ruby class ExampleMigration < ActiveRecord::Migration @@ -606,7 +607,7 @@ schema, and the `down` method of your migration should revert the transformations done by the `up` method. In other words, the database schema should be unchanged if you do an `up` followed by a `down`. For example, if you create a table in the `up` method, you should drop it in the `down` method. It -is wise to reverse the transformations in precisely the reverse order they were +is wise to perform the transformations in precisely the reverse order they were made in the `up` method. The example in the `reversible` section is equivalent to: ```ruby |