custom ordering activerecord data in rails

Question

I have 3 courses A(july 1), B(july 2), C(july 3).A and B is rated 4 and C is rated 5.

I want to order the course like this

C should come first because it was created latest and it has higher rating than others.

A should come second because it was created first than B

I cant use order because it wont give me what i need. any way to fix this?

Here is how i am fetching the data

@courses.order('updated_at DESC, average_rating DESC')

code

[
#<Course:0x00000009f3c128
  id: 6,
  tutor_id: 2,
  course_name: "name",
  course_subtitle: "sub",
  course_description: "<p>test</p> test\r\n",
  video_link: "https://www.youtube.com/watch?v=UVrQcieqD0U",
  course_language: "German",
  course_image: "finalse.png",
  created_at: Tue, 11 Jul 2017 05:03:03 UTC +00:00,
  updated_at: Tue, 11 Jul 2017 08:47:03 UTC +00:00,
  status: "accepted",
  average_rating: 2.5,
  rated_time: nil>,
 #<Course:0x00000008139608
  id: 7,
  tutor_id: 2,
  course_name: "another",
  course_subtitle: "another subtuitle",
  course_description: "<p>course descrition</p>\r\n",
  video_link: "https://www.youtube.com/watch?v=uaTeZA-Gj7s",
  course_language: "Chinese",
  course_image: nil,
  created_at: Tue, 11 Jul 2017 10:40:45 UTC +00:00,
  updated_at: Tue, 11 Jul 2017 10:41:06 UTC +00:00,
  status: "accepted",
  average_rating: 2.5,
  rated_time: nil>,
 #<Course:0x0000000813bea8
  id: 8,
  tutor_id: 2,
  course_name: "asfas",
  course_subtitle: "were",
  course_description: "<p>asdfsadf</p>\r\n",
  video_link: "https://www.youtube.com/watch?v=xGytDsqkQY8",
  course_language: "English",
  course_image: nil,
  created_at: Wed, 12 Jul 2017 03:53:26 UTC +00:00,
  updated_at: Wed, 12 Jul 2017 04:32:33 UTC +00:00,
  status: "accepted",
  average_rating: 1.0,
  rated_time: nil>,

I guess you could sort it with something like: [pseudocode] if rate1 == rate2 then return time2 - time1 else return rate1 - rate2, assuming there is a sort method that takes a callback taking two parameters and returning the difference — Top Sekret
– Top Sekret, Commented Jul 12, 2017 at 7:43

Gagan Gami · Accepted Answer · 2017-07-12 07:57:39Z

1

Try:

Course.all.order("average_rating DESC, created_at ASC")

edited Jul 12, 2017 at 7:57

answered Jul 12, 2017 at 6:36

Gagan Gami

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3 Comments

Sushant Bajracharya Over a year ago

the only problem with this is that if A, B has a rating of 4 each but A was created first and B was created second, then B shows up first. If A had shown up first, I wud accept this answer

Gagan Gami Over a year ago

you can change it to created_at ASC

Gagan Gami Over a year ago

@SushantBajracharya : you don't need to define ASC as well, as default it take ASC order

Nimish Gupta · Accepted Answer · 2017-07-12 05:50:23Z

0

try Course.order({ created_at: :desc, rating: :desc })

This will sort first on created_at and if two records have same created_at the will sort on the basis of rating

answered Jul 12, 2017 at 5:50

Nimish Gupta

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4 Comments

Nimish Gupta Over a year ago

well, this should work. Could you please share the query fired on rails console. So that I can have a better idea of what's happening

Nimish Gupta Over a year ago

It is sorting on the basis of time correctly. But your problem is that the field is of type datetime so, no two records have same created_at value.

Sushant Bajracharya Over a year ago

it has to sort according to rating as well.

Nimish Gupta Over a year ago

see there may be following cases According the query above it will sort by rating only when it got two records with same created_at value. Which will obviously never be the case. Please tell me what should be result if Course A created_at 4July 4:03 rating 2 Course B created_at 4July 3:03 rating 3 Course C created_at 5July 4:10 raitng 1 Now should Course C should be at top because it has highest created_at or at the lowest because it has lowest rating

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