defmodule AshPostgres.Transformers.PreventMultidimensionalArrayAggregates do
@moduledoc "Prevents at compile time certain aggregates that are unsupported by AshPostgres"
use Spark.Dsl.Transformer
alias Spark.Dsl.Transformer
def after_compile?, do: true
def transform(dsl) do
resource = Transformer.get_persisted(dsl, :module)
dsl
|> Ash.Resource.Info.aggregates()
|> Stream.filter(&(&1.kind in [:list, :first]))
|> Stream.filter(& &1.field)
|> Enum.each(fn aggregate ->
related = Ash.Resource.Info.related(resource, aggregate.relationship_path)
type = Ash.Resource.Info.field(related, aggregate.field).type
case type do
{:array, _} ->
raise Spark.Error.DslError,
module: resource,
path: [:aggregates, aggregate.name],
message: """
Aggregate not supported.
Aggregate #{inspect(resource)}.#{aggregate.name} is not supported, because its type is `#{aggregate.kind}`, and the destination attribute is an array.
Postgres does not support multidimensional arrays with differing lengths internally. In the future we may be able to remove this restriction
for the `:first` type aggregate, but likely never for `:list`. In the meantime, you will have to use a custom calculation to get this data.
"""
_ ->
:ok
end
end)
repo = Transformer.get_option(dsl, [:postgres], :repo)
cond do
match?({:error, _}, Code.ensure_compiled(repo)) ->
{:error, "Could not find repo module #{repo}"}
repo.__adapter__() != Ecto.Adapters.Postgres ->
{:error, "Expected a repo using the postgres adapter `Ecto.Adapters.Postgres`"}
true ->
{:ok, dsl}
end
end
end