"Sort by likes" button in Agriculture and Air Quality topics does not sort correctly

[khadija-nur]

Sort by likes does not work in agriculture and air quality topics

• When you go to "https://publiclab.org/tag/air-quality" or "https://publiclab.org/tag/agriculture"
  and click on sort by drop down menu then filter by likes button the posts appear randomly
  instead of being in a descending order depending on the number of likes they have

• see below:

• After filtering, the first post has 11 likes, the third one has 7 and the fourth has 8 likes

Please show us where to look

https://publiclab.org/tag/agriculture?order=likes
https://publiclab.org/tag/air-quality?order=likes

What's your PublicLab.org username?

username: knur

Browser, version, and operating system

• Windows 10 OS
• Chrome browser

---

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[alvesitalo]

Hey, can I work on this?

[cesswairimu]

Hi @alvesitalo, we would love your help. Go ahead . Thanks

[ebarry]

Thank you for reporting this @khadija-nur -- this is a valuable contribution! 🤝
and thank you @@alvesitalo for putting in some work to fix this 😃

[alvesitalo]

Hi everyone, I tested locally with some posts but I can't see any problem with sorting by likes. Have you experienced this issue? @ebarry @cesswairimu

[cesswairimu]

@alvesitalo yeah, it is happening in production if you go to https://publiclab.org/tag/agriculture" and select sort by likes you will see the second and third post may have more likes than the first one. I will test locally see if I can replicate

[jywarren]

Hi all, thanks @khadija-nur for finding this, and @alvesitalo for looking deeper - it seems like it may be pretty intermittent, which can be really tough to debug.

I wonder if we are sorting by cached likes count versus a count "on the fly" - see the model for tracking and caching likes at:

plots2/app/models/node.rb

Lines 1039 to 1046 in 27a3839

	def toggle_like(user)
	nodes = NodeSelection.where(nid: id, liking: true).size
	self.cached_likes = if is_liked_by(user)
	nodes - 1
	else
	nodes + 1
	end
	end

The page itself is using cached_likes here:

plots2/app/controllers/tag_controller.rb

Lines 121 to 122 in 27a3839

	elsif params[:order] == 'likes'
	'node.cached_likes DESC'

But see how the template is using node.likers.count ? Which may cause another database query and not be very efficient.

plots2/app/views/notes/_card.html.erb

Line 55 in 27a3839

<li><a>Total Likes: <%= node.likers.size %></a></li>

node.likers is defined here, and seems to use a different query... than the cached_likes code. Could they be drifting apart because some folks may like, but then get banned? In any case we should be able to use node.cached_likes instead in the template. That should be a pretty simple fix for now!

plots2/app/models/node.rb

Lines 256 to 264 in 27a3839

	# users who like this node
	def likers
	node_selections
	.joins(:user)
	.references(:rusers)
	.where(liking: true)
	.where('rusers.status': 1)
	.collect(&:user)
	end

---

Notice also how we aren't filtering out spam users in the cached_likes calculation -- maybe we should do that too, just to get these better in sync?

[jywarren]

I'll spin out that last idea about filtering banned users from cached_likes into its own issue. It's just a one-line change too!

[jywarren]

I spun that out into a first-timers-only issue at #8639 !

I could do the same for the template change above too, if it's helpful?

[alvesitalo]

Cool, it is. Thank you for clarifying this bug @jywarren

[jywarren]

I just did that over at #8691 - thanks @alvesitalo!

[gauravahlawat81]

Hey @jywarren , I was trying to reproduce this error in my local environment, but I couldn't do it. The post were all sorted correctly and I observed the same here, I wonder if this issue is solved now or are am I missing something else here ? 🤔