Defining change set validations

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Goals

• Understand validations with Change Sets.
• Introduce validations into the Book Change Set.
• Define a custom validator.

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Reference: ActiveRecord validations

Validations

Supports validations through ActiveModel validations. Not all ActiveRecord validations are supported (e.g. uniqueness is not supported). Some common examples are...

• validates property_name, property_name, ..., presence - passes if the property or list of properties all have values present
• validates_with ClassName[, property: property_name] - calls #validate method in the identified class to determine if the property's value is valid; if no property_name is identified, it is used to validate the change set as a whole

example book change set with validations in app/change_sets/book_change_set.rb

# frozen_string_literal: true
class BookChangeSet < Valkyrie::ChangeSet
  property :title, multiple: true, required: true
  property :author, multiple: true, required: true
  property :series, multiple: false, required: false
  property :member_ids, multiple: true, required: false

  validates :title, :author, presence: true
  validates_with SeriesValidator
end

example custom validator in app/validators/series_validator.rb

# frozen_string_literal: true
class SeriesValidator < ActiveModel::Validator
  # ensure the property exists and is in the controlled vocabulary
  def validate(record)
    return ['Joe Pike', 'Elvis Cole', 'Elvis Cole/Joe Pike'].include? record.series)
    record.errors.add :series, "#{record.series} is not a valid series"
  end
end

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