How to make the right exception?

Question

Ruby on Rails

Hey! Guys, such a question: I use Yandex api to display a marker on the map, at the address from the form.
I wrote this method that receives json on request to Yandex, parses it into a hash and gets the coordinates

def get_coordinates
    addr = URI.encode(URI.decode(self.address))
    http = "http://geocode-maps.yandex.ru/1.x/?format=json&geocode=#{addr}"
    json = RestClient.get(http)
    parced_json = ActiveSupport::JSON.decode(json)
    parced_json["response"]["GeoObjectCollection"]["featureMember"][0]["GeoObject"]["Point"]["pos"]
  end

so that every time when rendering a page with a map, not to make a request to Yandex, I added the coordinates field to the table and write the coordinates to this field when creating an object
, the callback method in the model

before_save :set_coordinates

  def set_coordinates
    if address_changed?
      self.coordinates = get_coordinates
    end
  end

but the problem is that the user can enter a request that is not correct for Yandex, and it needs to be processed somehow,
I changed the method in this way

def get_coordinates
    begin
      addr = URI.encode(URI.decode(self.address))
      http = "http://geocode-maps.yandex.ru/1.x/?format=json&geocode=#{addr}"
      json = RestClient.get(http)
      parced_json = ActiveSupport::JSON.decode(json)
      parced_json["response"]["GeoObjectCollection"]["featureMember"][0]["GeoObject"]["Point"]["pos"]
    rescue NoMethodError
      self.errors.add(:coordinates)
    end
  end

but the error is written not in @messages={:coordinates=>["is invalid"]}>
but in the field coordinates

how to make it so that the error is sent to the right place?

Answer 1

def get_coordinates
    begin
      addr = URI.encode(URI.decode(self.address))
      http = "http://geocode-maps.yandex.ru/1.x/?format=json&geocode=#{addr}"
      json = RestClient.get(http)
      parced_json = ActiveSupport::JSON.decode(json)
      coordinates = parced_json["response"]["GeoObjectCollection"]["featureMember"][0]["GeoObject"]["Point"]["pos"]
    rescue NoMethodError
      coordinates = nil
      self.errors.add(:coordinates)
    end
    coordinates
  end