Faster Database Where For Rails Availability Calendar

I'm building a Ruby on Rails hostel bed reservation system and I'm looking for a better way to load my availability calendar. The below code works great for showing bed availabilit

Solution 1:

What Robbie is describing is capturing the data in bulk to present it in a second pass. You can do this:

@reservations = Reservations.where(bed_id: [ ... ], date: (from..to)).group_by do |r|
  [r.bed_id, r.date]
end

Where this returns a singular structure that should contain all the reservations in a way that can be easily indexed using both bed_id and a date. You can turn this into a two-tier structure if necessary, but it's usually not.

When iterating:

- current_user.beds.each do |bed|
  - reservation = @reservations[[bed.id,date]]
  - if reservation
    # ...

This practice of selectively, but aggressively eager-loading records usually works quite well when you're dealing with complex inter-dependencies that can't be easily expressed with an includes(..) element in your loading chain.

Also, remember in Ruby there's only two things that are logically false: literal false and nil. Everything else evaluates as logically true, including 0, empty strings, arrays and hashes. As such comparisons != nil are almost always extraneous and confusing, especially if you do double-negation like unless (x != nil).

If you're looking to be able to resolve a number of arbitrary date+bed pairs against the database you could make some kind of booking key that was a combination of date and bed_id then it'd be a lot easier to scan for these. You could do a WHERE booking_token IN (...) and have it all indexed, performant, and concise. It takes some advance planning though to do it properly. YYYY-MM-DD-bed_id could work as a first pass.

Solution 2:

For your view code, I would try:

= week_calendar events: @monthly_reservations, attribute: :datedo |date, appts|
  - current_user.beds.each do |bed|
    %p{style: "border: 1px solid black; padding: 5px; font-size: 10px;"}
      = [bed.name, @reservations[[date, bed.id]]].compact.join(":")