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elixirecto

Eval-ing paramaters in Elixir (with Ecto)

Have a look at the select() line below:

def query_group(user, group_by, filters \\[]) do
    from(Click)
    |> select([c], {c.^group_by, count(c)})
    |> where([c], c.link_user_id == ^user.id)
    |> where([c], ^filters)
    |> group_by([c], ^group_by)
    |> Repo.all
    |> Enum.map(&(Tuple.to_list &1))
  end

group_by is an atom. For example, if group_by = :platform, then in the select field, I need to get select([c], {c.platform, count(c)}).

What's the best way of approaching this?

Solution

  • You can also use field/2, as in select([c], {field(c, ^group_by), count(1)}) (not sure group_by needs to be pinned here but I think so)