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Edit text on optional db constraints for uniqueness validations [ci skip]

This commit is contained in:
Taylor Mingos 2015-02-04 11:04:07 -05:00
parent cd0ed12d1a
commit 3c57c8608f
1 changed files with 2 additions and 3 deletions
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5
guides/source/active_record_validations.md
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@ -606,9 +606,7 @@ This helper validates that the attribute's value is unique right before the
object gets saved. It does not create a uniqueness constraint in the database,
so it may happen that two different database connections create two records
with the same value for a column that you intend to be unique. To avoid that,
you must create a unique index on both columns in your database. See
[the MySQL manual](http://dev.mysql.com/doc/refman/5.6/en/multiple-column-indexes.html)
for more details about multiple column indexes.
you must create a unique index on that column in your database.
```ruby
class Account < ActiveRecord::Base
@ -628,6 +626,7 @@ class Holiday < ActiveRecord::Base
message: "should happen once per year" }
end
```
Should you wish to create a database constraint to prevent possible violations of a uniqueness validation using the `:scope` option, you must create a unique index on both columns in your database. See [the MySQL manual](http://dev.mysql.com/doc/refman/5.6/en/multiple-column-indexes.html) for more details about multiple column indexes or [the PostgreSQL manual](http://www.postgresql.org/docs/9.4/static/ddl-constraints.html) for examples of unique constraints that refer to a group of columns.
There is also a `:case_sensitive` option that you can use to define whether the
uniqueness constraint will be case sensitive or not. This option defaults to