Ash FrameworkAF
Ash Framework•4mo ago•
11 replies
Songyun

Ash Union Calculations

I'm still wrapping my head around polymorphic relationships and was wondering why a calculation on one needs to return a %Ash.Union{}?

E.g.

  def calculate(records, _, _) do
    Enum.map(records, fn record ->
      cond do
        record.checking_account ->
          %Ash.Union{type: :checking_account, value: record.checking_account}

        record.savings_account ->
          %Ash.Union{type: :savings_account, value: record.savings_account}

        true ->
          nil
      end
    end)
  end


I tried swapping out the return values above for the direct value, e.g. record.checking_account and that seemed to work, so what value is being added / what function is this playing here? I don't have multiple clauses in my condition yet as I'm still building things out (if that makes a difference). What was also surprising about this is that despite the calculation specifying a union type in the second argument (e.g. AccountImplementation), it was happy to return just the value. Thanks.
Solution
We don't check that calculation return values match their declaration (for performance reasons)
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