Ecto: Aggregate count of rows

[optikfluffel]

Hi, I'm trying to count the number of existing users in a small petproject of mine and currently came up with

number_of_users = Repo.all(from u in User, select: u.id) |> Enum.count

Is there a way to use something like

SELECT COUNT(*)   
FROM users;

with ecto?

Thanks in advance

[ericmj]

from(u in User, select: count(u.id)). You can find all query functions on Ecto.Query.API.

Please ask questions on the mailing list in the future.

[optikfluffel]

I tried that before but it just returns '\b'.

iex(6)> Repo.all(from(u in User, select: count(u.id)))
'\b'

Without the count everything looks ok:

iex(7)> Repo.all(from(u in User, select: u.id))       
[1, 2, 3, 4, 5, 6, 7, 8]

[lexmag]

[8] is only displayed as '\b'.

inspect [8] # => "'\\b'"
inspect [8], char_lists: :as_list # => "[8]"

[optikfluffel]

Thanks @lexmag :) this now did the trick. Still looks a little complicated, but works.

iex(1)> import Ecto.Query
nil
iex(2)> List.first Repo.all(from u in User, select: count(u.id))
8

[ericmj]

Use Repo.one if you want a single result.

[optikfluffel]

Cool, thanks again, works like a charm.

[hickscorp]

@optikfluffel I like very much to use the Repo.aggregate/3 function. In your case:

count = Repo.aggregate User, :count, :id
# Same as:
count = User |> Repo.aggregate(:count, :id)

[BenMorganIO]

merci @hickscorp