demarches-normaliennes/app/validators/geo_json_validator.rb

class GeoJSONValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    if options[:allow_nil] == false && value.nil?
      record.errors.add(attribute, :blank, message: options[:message] || "ne peut pas être vide")
    end

    begin
      RGeo::GeoJSON.decode(value.to_json, geo_factory: RGeo::Geographic.simple_mercator_factory)
    rescue RGeo::Error::InvalidGeometry
      record.errors.add(attribute, :invalid_geometry, message: options[:message] || "n'est pas un GeoJSON valide")
    end
  end
end