Rails JSON过滤器关联结果

Question

Users (with name) can have cards (with name) through collections (with number):

class User < ActiveRecord::Base
    has_many :collections
    has_many :cards, through: :collections
end
class Card < ActiveRecord::Base
    has_many :collections
    has_many :users, through: :collections
end
class Collection < ActiveRecord::Base
    belongs_to :user
    belongs_to :card
end

My cards API includes all cards and collections information:

class CardsController < ApplicationController
    def index
        @cards = Card.all
        render json: @cards, :include => :collections
    end
end

I would like to remove collections not owned by user queryparam. I tried:

@cards = @cards.includes(:collections).where(collections: { user_id: [nil, params[:user]] }) if params[:user].present?

It correctly outputs cards that the user owns and cards that nobody owns, but it filters out cards that are only owned by other users. I would like to have these too (all cards, including collections information only for the current user).

Answer 1

Try this in your CardsController :

@cards = Card.includes(:collections).filtered_cards(current_user.id).sort_by { |t| t.created_at }.reverse!

then in your Card model create a scope that filters out the user's cards, and the collections are not owned by anyone:

scope :filtered_cards, -> (user_id) {
  select { |card| card.collections.each { |col| col.user_id == user_id }.length > 0 || card.user_id == nil }
}

or

scope :filtered_cards, -> (user_id) {
  select { |card| card.collections.map(&:user_id).include?(user_id) || card.user_id = nil }
}

Hope it helps!