Bug on create unique index with scopes

[J-F-Liu]

For the following code:
property :modelnumber, String, :unique => [:brand, :name], :required => true

The generated SQL statement is:

CREATE UNIQUE INDEX "unique_products_brand" ON "products" ("modelnumber");
CREATE UNIQUE INDEX "unique_products_name" ON "products" ("modelnumber");

The correct SQL statement should be:
CREATE UNIQUE INDEX "unique_products_modelnumber" ON "products" ("modelnumber", "brand", "name")

[tillsc]

Belongs to datamapper/dm-validations#43

[J-F-Liu]

The validation works if I first create the table then add the unique argument.
I created a fix on property_set.rb and passed test on table creation, will send PR later.

[tpitale]

@J-F-Liu is the rest of your model like this?

property :name, String
property :brand, String

If so, I think the syntax for a unique index for these fields would be to use a symbol, like this:

property :modelnumber String, unique: :model_brand_name
property :brand String, unique: :model_brand_name
property :name String, unique: :model_brand_name

That is the intended use.