acrolink
How to pass "asc" or "desc" to the Ecto.query function
I have created some basic select list (asc, desc). I want to pass either strings to Ecto.query.
# order by order_by_expires
def order_by_expires(query, nil), do: query
def order_by_expires(query, direction) do
query |> order_by(direction: :expires)
end
The above does not work, I get the error:
Ecto.Query.CompileError) expected :asc, :desc or interpolated value in order_by, got: :direction
Marked As Solved
t0t0
I think you need to write:
order_by({direction, :expires})
Else direction: is the atom :direction.
I guess direction has to be converted to atom first:
if direction in ~W[asc desc], do: String.to_existing_atom(direction), else: :asc
Or much better, do pattern matching on direction:
defp do_order_by_expires(query, direction) do
query |> order_by({direction, :expires})
end
def order_by_expires(query, "desc") do
do_order_by_expires(query, :desc)
end
def order_by_expires(query, _) do
do_order_by_expires(query, :asc)
end
Also Liked
josevalim
Move the assignment out of the if:
def order_by_expires(query, direction) do
direction = if direction in ~W[asc desc], do: String.to_existing_atom(direction), else: :asc
query |> order_by({^direction, :expires})
end
You can also simplify it to:
def order_by_expires(query, direction) do
direction = if direction == "desc", do: :desc, else: :asc
query |> order_by({^direction, :expires})
end
acrolink
A little modification was needed to get it to work:
defp do_order_by_expires(query, direction) do
query |> order_by({^direction, :expires})
end
Thank you.
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