catra
Select by column
I have a Postgres view with 4 columns, two of them contains numbers. I want to create a function to get the sum of the elements depending on the column name.
This query is working well:
def sum_by_colum(column) do
Repo.aggregate(VwClientNodeBatteryStatus, :sum, column)
end
But I want to use something like:
from(vw in VwClientNodeBatteryStatus,
select: sum(vw.^column))
Because I can use Repo.one to get the popular {:ok, result} tuple. But I’m getting the following error:
`vw.^(column) is not a valid query expression. If you want to invoke vw.^/1 in a query, make sure that the module vw is required and that ^/1 is a macro
I guess Elixir/Ecto thinks that I have vw is a function. =S
Most Liked
gregvaughn
You’ll want to use field/2 (https://hexdocs.pm/ecto/Ecto.Query.API.html#field/2) to dynamically reference column names.
Untested code, but something like:
select sum(field(vw, ^column))
3
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