Some Reform/dry-v examples

Example 1

class FieldForm < Reform::Form
  property :key
  collection :field_options, form: FieldOptionForm
  
  validation do
    configure do
      option :form # include this line if you want access to your form in predicates
      
      config.messages_file = 'config/error_messages.yml' # if you define any custom predicates you must provide a message for them
      
      # custom predicates must be defined in the configure block
      def uniq_key?(value)
        # here I access the model id to check if the fields key is unique.
        # in a predicate you've got access to your form.
        Field.where.not(id: form.model.id).where(key: value).empty?
      end
    end
  
    required(:key).filled(:uniq_key?)
    requried(:field_options).filled(min_size?: 1)
  end
end

Example 2

class ExampleTwoForm < Reform::Form
  validation do
    configure do
      option :form # include this line if you want access to your form in predicates
      
      config.messages_file = 'config/error_messages.yml' # if you define any custom predicates you must provide a message for them

      def within_client_scope?(value)
        # here I am making sure that the profile_id is the id of a profile in the current organisation. 
        # the only time this could fail is if the user hacked his HTML form params, but still worth checking.
        !form.model.organisation.profiles.where(id: value).empty?
      end
    end
    
    required(:profile_id).filled(:within_client_scope?)
  end
end

UserExample

class ExampleUserForm < Reform::Form
  validation :authenticate_current_password do
    configure do
      option :form # include this line if you want access to your form in predicates
      
      config.messages_file = 'config/error_messages.yml' # if you define any custom predicates you must provide a message for them

      def account_authenticated?(password)
        form.model.authenticate(password)
      end
    end
    
    required(:current_password).filled(:account_authenticated?)
  end
end

I would love to be able to inject the current user into my schemas as that would open a world of possibilities for permission based validation. At the moment it isn't such an issue as we have a couple of distinct roles which have their own forms to ensure that only attributes that they can change are available.
However moving forward we would like to have user customisable permissions and in this case we would need to be able to define rules whereby a record is invalid if certain attributes were changed based on the users permissions.