** (Postgrex.Error) ERROR 42883 (undefined_function) operator does not exist: money_with_currency + money_with_currency
query: UPDATE "wallets" AS w0 SET "balance" = w0."balance" + $1::money_with_currency WHERE (w0."id" = $2)
hint: No operator matches the given name and argument types. You might need to add explicit type casts.
I have run the “aggregate functions for money” migration although I didn’t think it would help since this is +, not sum.
I think maybe this kind of syntax just isn’t possible? Can anyone confirm?
To install the required functions in Postgres the readme now says:
Plus operator +
ex_money defines a migration generator which, when migrated to the database with mix ecto.migrate, supports the + operator for :money_with_currency columns. The steps are:
Generate the migration by executing mix money.gen.postgres.plus_operator
Migrate the database by executing mix ecto.migrate
Formulate an Ecto query to use the + operator
iex> q = Ecto.Query.select Item, [l], type(fragment("price + price"), l.price)
#Ecto.Query<from l0 in Item, select: type(fragment("price + price"), l0.price)>
iex> Repo.one q
[debug] QUERY OK source="items" db=5.6ms queue=0.5ms
SELECT price + price::money_with_currency FROM "items" AS l0 []
#Money<:USD, 200>]
Let me know if you have any feedback and please file any bugs on the issue tracker.
What amazing timing!
Thanks @kip . You’re genuinely an idol.
I’ll test that now and write the result here.
Update: I tried it for the use case described above and it works perfectly!
ex_money_sql is the library that implements database support for Money.t types. After that, its Postgres (or MySQL potentially or some other database) that is doing all the work.
The + operator can be overloaded in Postgres and the implementation of that for a :money_with_currency type is here