带有JSON参数的Rails Active Record查询的问题

Question

I have a Notification model with a notification_objects parameter. Notification.first.notification_objects returns an array of hashes. I've created a @notification_objects variable that holds the an array of hashes with the same key/value pairs (except with symbols instead of strings for keys). How can I find this first Notification using Notification.where() ? Stringifying the keys in @notification_objects did not work. I'm using Postgres 9.4 and Rails 4.2.

[18] pry(main)> Notification.first.notification_objects
=> [{"class_name"=>"Ad", "ar_object_id"=>1}]

[19] pry(main)> @notification_objects
=> [{:class_name=>"Ad", :ar_object_id=>1}]


# both as_json and to_json do not work here:
[20] pry(main)> Notification.where(notification_objects: @notification_objects.as_json)
=> []

[21] pry(main)> @notification_objects.as_json
=> [{"class_name"=>"Ad", "ar_object_id"=>1}]

[22] pry(main)> Notification.first.notification_objects.as_json == @notification_objects.as_json
=> true

Answer 1

You could try to use .to_json instead of .as_json

Notification.where(notification_objects: @notification_objects.to_json)

.to_json returns a JSON string representing the model.

references: http://apidock.com/rails/ActiveRecord/Serialization/to_json