Set values as boolean in array and change position in ruby (Rails 5)

Question

I have a set of objects through ActiveRecord, and need to iterate through them to ID a set of conditions.

def get_smith_listings
  Listing.joins(:spec).where('specs.broker ilike ?', '%smith%')
end

@listings = Listings.all #actually a built query

@listings.sort_by { |item| item.get_smith_listings? ? 0 : 1 }

=> EXPLAIN for: SELECT "listings".* FROM "listings" INNER JOIN "specs" ON "specs"."listing_id" = "listings"."id" WHERE (specs.agent ilike '%smith%')
                                      QUERY PLAN
--------------------------------------------------------------------------------------
 Nested Loop  (cost=0.28..848.56 rows=1 width=668)
   ->  Seq Scan on specs  (cost=0.00..840.25 rows=1 width=4)
         Filter: ((agent)::text ~~* '%smith%'::text)
   ->  Index Scan using listings_pkey on listings  (cost=0.28..8.30 rows=1 width=668)
         Index Cond: (id = specs.listing_id)

(the nature of the question has changed slightly as I've zeroed in on the method required)

I'm having trouble structuring this in a way that a) gets my method recognized (new to helpers) and sets up the query to sort using the boolean.

UPDATE: For this seeking clarification, this is the direction I'm trying to take on this problem: https://www.mateoclarke.com/blog/2015/10/14/what-i-learned-boolean-ruby/

don't know if I got it right... you want an array where the first ones have agent like smith and the last ones who don't? — Ronan Lopes
– Ronan Lopes, Commented Apr 25, 2018 at 19:56
Yup - I want to take everything that fits 'group' and move it to the beginning of the array. — Boucherie
– Boucherie, Commented Apr 25, 2018 at 19:57
so you want just order? like [ 'agent like smith true', 'agent like smith false']? — Ronan Lopes
– Ronan Lopes, Commented Apr 25, 2018 at 20:00
made an answer... don't know if I got it right, but take a look — Ronan Lopes
– Ronan Lopes, Commented Apr 25, 2018 at 20:04

steenslag · Accepted Answer · 2018-04-25 20:15:47Z

2

Enumerable#partition does that: it results in an array of 2 arrays. The first contains all items for which the block is true, the second are the falses.

answered Apr 25, 2018 at 20:15

steenslag

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4 Comments

Boucherie Over a year ago

so (@listing).partition { |v| v.group? } ?

steenslag Over a year ago

I'm just guessing here ( have no data and no Rails) , I would try groups = @listings.partition.joins(:spec).where('specs.agent ilike ?', '%smith%')

Ronan Lopes Over a year ago

that wouldn't work... you can't apply joins on an enumerable. Also, partition needs a block with the condition to separate the objects based on that condition, and it's applied over each record, so you can't use where. So, something like this could work: @listings.includes(:spec).partition{|l| l.spec.agent.include?("smith")}

steenslag Over a year ago

@RonanLopes Even without Rails knowledge, yours seems to make much more sense.

Ronan Lopes · Accepted Answer · 2018-04-26 15:15:37Z

1

You can do it like this:

group = Listings.all.joins(:spec).where('specs.agent ilike ?', '%smith%') +
 Listings.all.joins(:spec).where.not('specs.agent ilike ?', '%smith%')

So it will put on the group variable first the ones that match the condition, and after those, the ones that doesn't

EDIT: don't know exactly why you need a separate method to do that (since the way I showed before would give you the correct order anyway). But there's a problem with the syntax you showed on edit: you're trying to call a instance method that calls the whole ActiveRecord method where (same problem as the answer of steenslag). If you wanna do the way you presented, I think this way should work better:

#this method should be on Listing model
def get_smith_listings?
  self.spec.broker.to_s.include?("smith")
end

@listings = Listings.includes(:spec).all #important to avoid n+1 queries

# here the 0 or 1 position will depende the true/false order you want
@listings.sort_by { |item| item.get_smith_listings? ? 0 : 1 }

I still don't got why you wanna do it that way and guess there's probably a better way to do what you want... but for now I can't help more than that. Good luck!

edited Apr 26, 2018 at 15:15

answered Apr 25, 2018 at 20:03

Ronan Lopes

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6 Comments

Boucherie Over a year ago

This is good, but I need to be able to set group = @listings.joins(:spec).where('specs.agent ilike ?', '%smith%') as a condition to be called - hence the need for a boolean

Ronan Lopes Over a year ago

@Boucherie don't got it right so. Can you explain with more details what you're trying to do? please update the question

Boucherie Over a year ago

Updated the question.

Boucherie Over a year ago

Damn...yeah, the dev who set this up agrees - just got pointed to ransack gem docs

Boucherie Over a year ago

Okay, this is right, and I'm going to mark it right, but my strategy shifted considerably - this helped parse through different methodologies though, so thanks :)

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