EctoMoney

Repo to demo a possible bug in ex_money_sql or ecto.

Steps to reproduce

# insert some moneys:

%EctoMoney.Money{amount: Money.new("100.00", :USD)} |> EctoMoney.Repo.insert()
%EctoMoney.Money{amount: Money.new("50.00", :USD)} |> EctoMoney.Repo.insert()
%EctoMoney.Money{amount: Money.new("75.00", :USD)} |> EctoMoney.Repo.insert()

# run a custom sum query and cast the response to a Money struct:

import Ecto.Query

query =
  from(
    money in "moneys",
    select: %{
      total: type(sum(money.amount), EctoMoneyType),
    }
  )

EctoMoney.Repo.all(query)

Expected:

This is the response you get when using ex_money_sql == 1.3.1

[%{total: #Money<:USD, 225.00>}]

Actual:

Using ex_money_sql ~> 1.4, with the new parameterized type, we get a compilation error:

** (UndefinedFunctionError) function Money.Ecto.Composite.Type.type/0 is undefined or private. Did you mean one of:

      * type/1

    (ex_money_sql 1.4.2) Money.Ecto.Composite.Type.type()
    (ecto 3.5.7) lib/ecto/type.ex:421: Ecto.Type.match?/2
    (ecto 3.5.7) lib/ecto/query/builder.ex:646: Ecto.Query.Builder.assert_type!/3
    (ecto 3.5.7) lib/ecto/query/builder.ex:415: Ecto.Query.Builder.escape/5
    (ecto 3.5.7) lib/ecto/query/builder.ex:462: Ecto.Query.Builder.escape_with_type/5
    (ecto 3.5.7) lib/ecto/query/builder/select.ex:111: anonymous fn/4 in Ecto.Query.Builder.Select.escape_pairs/4
    (elixir 1.11.3) lib/enum.ex:1533: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (ecto 3.5.7) lib/ecto/query/builder/select.ex:82: Ecto.Query.Builder.Select.escape/4

Workarounds

You can remove the casting, but then you get back a tuple instead of a Money struct.

query =
  from(
    money in "moneys",
    select: %{
      total: sum(money.amount),
    }
  )

EctoMoney.Repo.all(query)

Results in:

[%{total: {"USD", #Decimal<225.00>}}]