Class: ExactlyOnePresentValidator

Inherits:
ActiveModel::Validator
  • Object
show all
Defined in:
app/validators/exactly_one_present_validator.rb

Overview

ExactlyOnePresentValidator

Custom validator for ensuring that exactly one of the specified fields or associations is present.

Options:

  • :fields - Array, Symbol, or Proc for database columns and custom methods.

    Uses the reader method (public_send) to get the value, so any custom
getter definition will be used.

  • :associations - Array, Symbol, or Proc for ActiveRecord associations.

    Uses ActiveRecord's association reflection to get the value directly,
bypassing any custom reader methods.

  • :error_key - Symbol for the error key (default: :base)

  • :message - String or Proc for custom error message

At least one of :fields or :associations must be provided. Both can be used together.

The validator supports three types of values for :fields and :associations:

  • Array: Static list of field/association names

  • Symbol: Method name that returns an array of field/association names

  • Proc/lambda: Dynamic resolution executed in the record’s context

Examples:

# Using :fields with an Array (database columns and custom methods)
class MyModel < ApplicationRecord
  validates_with ExactlyOnePresentValidator, fields: %i[name url identifier]
end

# Using :associations with an Array (ActiveRecord associations)
class MyModel < ApplicationRecord
  belongs_to :project, optional: true
  belongs_to :group, optional: true
  validates_with ExactlyOnePresentValidator, associations: %i[project group]
end

# Combining :fields and :associations
class MyModel < ApplicationRecord
  belongs_to :custom_status, optional: true
  validates_with ExactlyOnePresentValidator,
    fields: %i[system_defined_status],
    associations: %i[custom_status]

  def system_defined_status
    @system_defined_status ||= SystemStatus.find_by(id: system_status_id)
  end
end

# Using a Symbol to call a method that returns fields dynamically
class MyModel < ApplicationRecord
  validates_with ExactlyOnePresentValidator, fields: :dynamic_fields

  def dynamic_fields
    some_condition? ? %i[field_a field_b] : %i[field_c field_d]
  end
end

# Using a Proc/lambda for dynamic field resolution
class MyModel < ApplicationRecord
  validates_with ExactlyOnePresentValidator, fields: -> {
    self.type == 'TypeA' ? %i[field_a field_b] : %i[field_c field_d]
  }
end

# Using custom error key and message
class MyModel < ApplicationRecord
  validates_with ExactlyOnePresentValidator,
    fields: %i[name url],
    associations: %i[project],
    error_key: :custom_key,
    message: 'Please provide exactly one identifier'
end

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ ExactlyOnePresentValidator

rubocop:disable Gitlab/BoundedContexts,Gitlab/NamespacedClass – Validators can belong to multiple bounded contexts



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# File 'app/validators/exactly_one_present_validator.rb', line 75

def initialize(*args)
  super

  return unless options[:fields].blank? && options[:associations].blank?

  raise 'ExactlyOnePresentValidator: :fields or :associations options are required'
end

Instance Method Details

#validate(record) ⇒ Object 



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# File 'app/validators/exactly_one_present_validator.rb', line 83

def validate(record)
  resolved_fields = resolve_option(record, :fields)
  resolved_associations = resolve_option(record, :associations)
  all_keys = resolved_fields + resolved_associations

  present_values = present_field_values(record, resolved_fields) +
    present_association_values(record, resolved_associations)

  return if present_values.one?

  add_validation_error(record, all_keys)
end