diff options
Diffstat (limited to 'guides/source')
| -rw-r--r-- | guides/source/active_record_migrations.md | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/guides/source/active_record_migrations.md b/guides/source/active_record_migrations.md index b89485b945..2aae35223a 100644 --- a/guides/source/active_record_migrations.md +++ b/guides/source/active_record_migrations.md @@ -246,7 +246,8 @@ class AddUserRefToProducts < ActiveRecord::Migration[5.0] end ``` -This migration will create a `user_id` column and appropriate index. +This migration will create a `user_id` column and appropriate index. +For more `add_reference` options, visit the [API documentation](http://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-add_reference). There is also a generator which will produce join tables if `JoinTable` is part of the name: @@ -355,6 +356,13 @@ end will append `ENGINE=BLACKHOLE` to the SQL statement used to create the table (when using MySQL or MariaDB, the default is `ENGINE=InnoDB`). +Also you can pass the `:comment` option with any description for the table +that will be stored in database itself and can be viewed with database administration +tools, such as MySQL Workbench or PgAdmin III. It's highly recommended to specify +comments in migrations for applications with large databases as it helps people +to understand data model and generate documentation. +Currently only MySQL and PostgreSQL supports comments. + ### Creating a Join Table The migration method `create_join_table` creates an HABTM (has and belongs to @@ -454,6 +462,7 @@ number of digits after the decimal point. are using a dynamic value (such as a date), the default will only be calculated the first time (i.e. on the date the migration is applied). * `index` Adds an index for the column. +* `comment` Adds a comment for the column. Some adapters may support additional options; see the adapter specific API docs for further information. |