CODEWITHSUNDEEP
rubyvalidationsinatradatamapper
schwift
schwift

Reputation: 339

Validate uniqueness on combined fields in DataMapper

I want to be able to put entries in my database where the manufacturer will be represented multiple times but not the same combination of manufacturer and model. So "Sony(manufacturer), Tv(model)" is okay "Sony(manufacturer), OtherTv(model)" but the third entry "Sony(manufacturer), Tv(model)" is not okay since the combination of manufacturer and model is not unique. I tried with the :key => true validation but it doesn't seem to work. And I cannot do something like validates_uniqueness_of :manufacturer AND :model I guess. So how do you do it?

class Tvs
  include DataMapper::Resource

  property :id,           Serial
  property :manufacturer, String, :key => true
  property :model,        String, :key => true

  validates_uniqueness_of :
end

Upvotes: 3

Views: 1350

Answers (4)

Gus Shortz
Gus Shortz

Reputation: 1771

If you remove the property :id Serial line, you will end up with a composite key (Manufacturer, Model), that will not allow duplicate Models for a particular Manufacturer.

Upvotes: 0

mrgordon
mrgordon

Reputation: 130

class Tvs
  include DataMapper::Resource

  property :id,           Serial
  property :manufacturer, String, :unique_index => :manufacturer_model
  property :model,        String, :unique_index => :manufacturer_model

  validates_is_unique :model, :scope => :manufacturer
end

I needed to modify the example to use "validates_is_unique" to get this to work.

Upvotes: 0

namelessjon
namelessjon

Reputation: 907

You can actually go with:

class Tvs
  include DataMapper::Resource

  property :id,           Serial
  property :manufacturer, String, :unique_index => :manufacturer_model
  property :model,        String, :unique_index => :manufacturer_model

  validates_uniqueness_of :model, :scope => :manufacturer
end

This will also give you a unique index in the database.

Upvotes: 5

schwift
schwift

Reputation: 339

Nevermind. It seems this did the job:

class Tvs
  include DataMapper::Resource

  property :id,           Serial
  property :manufacturer, String, :unique_index => true
  property :model,        String, :unique_index => true

  validates_uniqueness_of :model, :scope => :manufacturer
end

Upvotes: 0

Related Questions