```ruby
# frozen_string_literal: true
class TimeFrameGroup < ActiveRecord::Base
  has_many :time_frames, inverse_of: :group, foreign_key: :group_id

  validates :label, presence: true, uniqueness: true
  validates :group_date, presence: true

  def to_s
    label
  end
end
```

Fix TimeFrameGroup validations to accomodate migrations
user
```ruby
# frozen_string_literal: true
class TimeFrameGroup < ActiveRecord::Base
  has_many :time_frames, inverse_of: :group, foreign_key: :group_id

  validates :label,
    presence: { if: -> { respond_to?(:label) } },
    uniqueness: { if: -> { respond_to?(:label) } }

  validates :group_date, presence: true

  def to_s
    label
  end
end
```
assistant