```ruby
class Event < ActiveRecord::Base
  has_many :participations, class_name: EventParticipation.name, dependent: :destroy
  has_many :users, through: :participations
end
```

Add validate presence to Event model
user
```ruby
class Event < ActiveRecord::Base
  has_many :participations, class_name: EventParticipation.name, dependent: :destroy
  has_many :users, through: :participations

  validates :name, presence: true
end
```
assistant