Get all columns of each distinct records in rails

Question

I want to get distinct records in rails. For that I see this Rails: how can I get unique values from column

But the issue is that by this solution I only get the Ids .

ViewsLog.uniq.pluck(:unit_id)
[24, 21, 23, 4, 16, 5, 7]

I want all columns of uniq unit_id

Distinct records based on what? What does your model look like? — shivam, Dec 17 '15 at 07:38
My model is ["id", "user_id", "unit_id", "unit_type", "is_billed", "created_at", "updated_at", "user_credit", "deleted_at", "campaign_id"] and I want all distinct records on unit_id — Haseeb Ahmad, Dec 17 '15 at 07:39

score 9 · Accepted Answer · edited Dec 17 '15 at 07:41

9

You can use group; it gives you all distinct records:

 ViewsLog.group(:unit_id)

edited Dec 17 '15 at 07:41

etdev

answered Dec 17 '15 at 07:33

Vishal JAIN

1

Is it only applicable on primary keys? Because when I do this it gives an error G::GroupingError: ERROR: column "surveys.id" must appear in the GROUP BY clause or be used in an aggregate function – Haseeb Ahmad Dec 17 '15 at 07:49
if your using `primary_key` then there is no chances of repetition of same id again n again it is handled by database. and it is applicable for all types of columns – Vishal JAIN Dec 17 '15 at 07:51
NO NO this isnt primary key – Haseeb Ahmad Dec 17 '15 at 07:52
@HaseebAhmad which database you are using?? and i think you are trying to select other columns that are not present in query – Vishal JAIN Dec 17 '15 at 07:53
Postgresql...No I write the same query – Haseeb Ahmad Dec 17 '15 at 07:56
@HaseebAhmad i think you are attached tag of `mysql` i am not sure it is working in `Postgresql` – Vishal JAIN Dec 17 '15 at 07:58
Yes according to myql its fine..n I find its equivalent in postgresql ....Thanks :) – Haseeb Ahmad Dec 17 '15 at 07:59
@VishalJAIN You can use group on only the column which are using in select statement or if you using aggregate functions. To get distinct record check my answer below. – Vishal Zambre Dec 19 '15 at 20:22

Vishal Zambre · Answer 2 · 2015-12-19T20:24:59.563

4

In rails to get distinct record can be used

ViewsLog.distinct(:unit_id)

If you are using postgres and have json type in a table then need to write like follow

ViewsLog.select('distinct on (views_logs.unit_id) views_logs.*')

Because postgres is not supporting to distinct if there is a json type filed in your table.

edited Dec 19 '15 at 20:24

answered Dec 19 '15 at 20:16

Vishal Zambre

`distinct` is giving a error in `rails 3.2` from which version of rails this feature is supporting?? – Vishal JAIN Dec 21 '15 at 08:38
1

`ViewsLog.select('distinct on (views_logs.unit_id) views_logs.*')` Does not work in Rails 6.0.3.1 either – JotK. Jun 11 '20 at 10:50

2 Answers2