Automatically Validate Uniqueness of Columns with Scope

The first cut at Schema Validations only applied validates_uniqueness_of for single-column unique indexes. This removed 80% of the cases in my code base but there were still cases where a scope was specified that lingered. Not any more.

The plugin now automatically generates validates_uniqueness_of with scope for multi-column unique indexes as well.

As always, there are some assumed conventions – which I believe will handle close to 99% of cases – around how to decide which column to validate versus which columns to consider part of the scope. The column to validate is chosen to be either:

With all remaining columns considered part of the scope, following, what I believe to be, a typical typical composite unique index column ordering.

So, for example, given either of the following two statements in your schema migration:

add_index :states, [:country_id, :name], :unique => trueadd_index :states, [:name, :country_id], :unique => true

The plugin will generate:

validates_uniqueness_of :name, :scope => [:country_id]

My next stop is to have a look at simple column constraints such as IN('male', 'female') and turn them into validates_inclusion_of :gender, :in => ['male', 'female'].

Perhaps tomorrow :)