CODEWITHSUNDEEP
ruby-on-rails
steven_noble
steven_noble

Reputation: 4203

How to simplify this method?

In reports.rb, I have:

has_and_belongs_to_many :elements

In elements.rb, I have:

has_and_belongs_to_many :reports

The following method works, but it seems longer than it should be:

@elements = []
Element.all.each do |element|
  @elements << element if element.reports.empty?
end

I've tried the following, but it doesn't work as there is no reports column:

@element = Element.where(reports.empty?)

Unfortunately, all the words I've tried punching into the Rails API references — find, etc — are so generic that I can't find a method that works that way that you can see I when where to work. Is there one? Or is there some other way I can simplify this method?

Upvotes: 0

Views: 82

Answers (2)

steven_noble
steven_noble

Reputation: 4203

Answer turned out to be:

@elements = Element.all.keep_if {|e| e.reports.empty?}

Upvotes: 0

Ned Ruggeri
Ned Ruggeri

Reputation: 1108

I can think of one way to do this in a low-level way.

Element
  .joins("LEFT OUTER JOIN element_reports")
  .group("elements.id")
  .having("element_reports.id IS NULL")

This at least pushes the responsibility for filtering to the DB, instead of fetching all the records. This should be a win especially if there are many records, or if they are particularly fat.

Upvotes: 1

Related Questions