Find with condition in Rails

Question

I am working on a project where users can create events with limited seats, and register and attend other events.

So far, I have an event, user, and seat model. And have removed the ability for users to create duplicate seats in my Seat model.

class Event < ActiveRecord::Base
  validates :title, :from_date, :from_time, :number_of_seats, presence: true
  belongs_to :user
  has_many :seats
end

class Seat < ActiveRecord::Base
  validates :event_id, :user_id, presence: true
  validates_uniqueness_of :user_id, :scope => :event_id
  belongs_to :event
  belongs_to :user
end

Currently, I have a page that lists all the available events. What I am trying to do is create a query of all the events the user is attending, and remove them from the page (or let the user know they are already attending).

I was able to create a page of all the classes a user is attending with this in my seats controller:

def index
  @seats = Seat.where(user_id: current_user.id)
end

And this on the page:

<h1 class="page-header">My Classes</h1>
    <% @seats.each do |p| %>
        <%= link_to Event.find(p.event_id).title, p %>
    <% end %>

I have tried solving this problem using Find with conditions: Stack Overflow

It got me close, but no cigar...

How can I create an Active Record Query that returns all Events a user is NOT attending?

Answer 1

You can use .where.not:

<% Event.where.not(id: @seats.map(&:event_id)).each do |p| %>
   <...>
<% end %>