No problem I appreciate your questions, and I while we definitely want to improve the documentation, having these kinds of questions here in the forum will help other people when they have similar questions. Documentation improvements are a longer term type thing, but this will help people in the short term

Hey @tellesleandro i just wanna say that your questions and the ensuing discussion is very helpful for newbies like me. Thanks for asking these questions!

You’d use calculations for this:

calculations do
  calculate :for_patio, :boolean, expr(exists(patios, id == ^arg(:id)) do
    argument :id, :uuid, allow_nil?: false
  end

  calculate :for_parceiro, :boolean, expr(exists(parceiros_precos_estadias, parceiro_id == ^arg(:parceiro_id) and voucher == ^arg(:voucher)))
end

And then you can query like

query =
  Resource
  |> Ash.Query.filter(for_parceiro(parceiro_id: parceiro_id, voucher: voucher))

# or 

query =
  Resource
  |> Ash.Query.filter(for_patio(patio_id: patio_id))

# or combine them

query =
  Resource
  |> Ash.Query.filter(for_parceiro(parceiro_id: parceiro_id, voucher: voucher) and for_patio(patio_id: patio_id))

# they can also be combined in ways you can't combine your example

query =
  Resource
  |> Ash.Query.filter(for_parceiro(parceiro_id: parceiro_id, voucher: voucher) or for_patio(patio_id: patio_id))

You cold then call a code interface and provide this query

YourResource.read(..., query: query)

Or use the underlying api for it

YourResource
|> Ash.Query.filter(....)
|> YourApi.read!()