```ruby
class Employment < ActiveRecord::Base
  belongs_to :partner
  belongs_to :professional

  attr_accessible :role
end
```

Add validation and make partner idan accessible attribute
user
```ruby
class Employment < ActiveRecord::Base
  belongs_to :partner
  belongs_to :professional

  attr_accessible :role, :partner_id
  validates :role, presence: true
end
```
assistant