mlesin
Ecto: select from generated_series only
I have table “tasks” with following fields:
id:bigint
canceled:date
done:date
And I have SQL query in this form:
SELECT date_trunc('day', date):: date as date,
(SELECT COUNT(*) FROM tasks WHERE date>="canceled") "canceled",
(SELECT COUNT(*) FROM tasks WHERE date>="done" AND (date<"canceled" or canceled isnull)) "done"
FROM generate_series('2020-01-01', '2020-01-10', '1 day'::interval) AS date
ORDER BY date
And I spent a lot of time googling if it is possible to wrap it in ecto query form without any success.
The main problem is I can’t write something like from( date in fragment(...)) and I can’t see how I can reformulate this query using joins to be able to fit into ecto restrictions on fragment() usage, because subqueries are using “less-than” or “more-than” comparisons of dates.
Any suggestions are welcome.
Marked As Solved
idi527
Maybe you can express generate_series('2020-01-01', '2020-01-10', '1 day'::interval) as a CTE with Ecto.Query — Ecto v3.14.0.
"date"
|> with_cte("date", as: fragment("select generate_series('2020-01-01', '2020-01-10', '1 day'::interval) as date"))
|> select([d], %{date: fragment("date_trunc('day', ?)", d.date), cancelled: fragment("select 1")})
|> Repo.all()
Also Liked
mlesin
I found a workaround for me: for this exact case it is better to use AyeSQL instead of Ecto.
first of all, it allows me to have much more readable code (at least for me: it’s almost plain SQL) and, at last but not least, it’s working for my case 
With AyeSQL, I’m able to dynamically combine all my filter cases inside pretty complex queries.
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