Embeded document with belong_to association in Mon

问题:

I have models like bellow. i want to query events for user with different kind of statuses by guests 'list'. If am not wrong guests list should be embeded in events? If my model design are wrong i`m open for different solution.

class User
  include Mongoid::Document

end

class Events
  include Mongoid::Document

  embeds_many :guests
end

Class Guests
  include Mongoid::Document

  embed_in :event
  belongs_to :user

  field :status

end

回答1:

The model structure is wrong as in Mongo you only keep the information in embedded documents which are required only in parent document.

If in guests you have only status field, then you can try this,e.g., two status type present or not present

class User
  include Mongoid::Document
  has_and_belongs_to_belongs_to :event, :inverse_of => "present_guests"
  has_and_belongs_to_belongs_to :event, :inverse_of => "not_present_guests"
end

class Event
  include Mongoid::Document
  has_and_belongs_to_many :present_guests, :class_name => "User", :inverse_of => "present_guests"
  has_and_belongs_to_has_many :not_present_guests, :class_name => "User", :inverse_of => "not_present_guests"
end

then you can query with the status like

Event.first.present_guests

回答2:

I believe that model structure would work.

Here's an example query to get all events with guests with the 'waiting' status:

Events.where('guests.status' => 'waiting')

Here's another example to, given an event, get all that event's guests with 'waiting' status:

event = Events.first # get the desired event
event.guests.where(:status => 'waiting')

Finally, you should name your models singular names (User, Event, Guest). Also, your Guest model has some typos I fixed below:

class User
  include Mongoid::Document

end

class Event
  include Mongoid::Document

  embeds_many :guests
end

class Guest
  include Mongoid::Document

  embedded_in :event
  belongs_to :user

  field :status
end