Rails ActiveRecord select distinct records ordered by timestamp

Question

In the following table of data:

I am trying to select from this table the records that are distinct based off of the columns itemable_id, itemable_type, and user_id. I also want the records sorted by last_viewed_at. In rails, I have been able to get the records to be distinct, but every way I try always gets record ID 1 instead of 4 for ThingType1 that has itemable_id 32. Essentially, the record set iI'm trying to end up with is one with rows with IDs 4, 3, and 2. How can i do this efficiently?

Gautam · Answer 1 · 2020-08-14T03:10:17.140

0

You can use group to get a group of distinct records and then order them by asc or desc -

UserItemView.select(:user_id, : itemable_type, :itemable_id).group(:user_id, : itemable_type, :itemable_id).order(last_viewed_at: :desc)

edited Aug 14 '20 at 03:10

answered Aug 14 '20 at 02:12

Gautam

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Unfortunately that gives me a `# – ryanpitts1 Aug 14 '20 at 02:32
Yup, i'm running this: `UserItemView.group(:itemable_id, :itemable_type, :user_id).order(last_viewed_at: :desc)` – ryanpitts1 Aug 14 '20 at 03:01
I have updated the answer, can you please try that? – Gautam Aug 14 '20 at 03:10
now i get `# – ryanpitts1 Aug 14 '20 at 03:31
You can use `sort_by` instead of `order ` - UserItemView.select(:user_id, : itemable_type, :itemable_id).group(:user_id, : itemable_type, :itemable_id).sort_by{| last_viewed_at |} – Gautam Aug 14 '20 at 04:31

Rails ActiveRecord select distinct records ordered by timestamp

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