View in preferred currency

[MissStabby]

I'm going on a trip that has people from various countries, and the trip itself is in another country
(in total 3 different currencies are involved)
While it's good to write the payments in the currency that they are paid in, it would be nice to have a preview option that shows prices in a currency the user is most familiar with to get a better grasp on the expense value.

like "preview in Euro / USD / RMB / JPY" etc. So inside the database everything is still stored and calculated in the original currency but in the UI it shows (either as extra or replacement) the preferred currency.

[krokosik]

That would require integration with some sort of financial API. I am not familiar with any service that offers it for free with reasonable rate limits :/

[delta0815]

I have no idea about coding and APIs but from an enduser-perspective I could also live with a "convert now" during the entry of a new transaction and an option when you finally do the cashout with your friends. With this is would only trigger an API call when needed

[krokosik]

Sounds reasonable, altough a just daily request would also sound like a sane approach to me, but this is just my point of view. Some people might also want to convert their expenses based on the expense date (in retrospect), so keeping a cache of daily exchange rates sounds like a good and fairly simple option to me. I imagine 2 user flows:

1. Convert an individual expense, providing an input field for the exchange rate with today's echange rate as default. If someone needs a more up to date one, which seems extreme, in my experience daily fluctuations are rather insignificant for personal expenses, they can input their own. There should also be a calendar picker to fetch the exchange rate from a particular date.
2. Convert a balance. Here too, we see an input field, where we can apply a fixed exchange rate to an entire balance OR apply the rate on a per expense basis, from their creation date.

The preview feature would be easy to add on top of that, but I would keep it behind a toggle in group settings. This raises a question, which approach should a balance view use for that? Should it have a fixed rate from today?

What do you think? @Silther @delta0815 @MissStabby
I don't know how Splitwise handles that as I never paid for their Pro tier.

[Silther]

Just to have enough context, how does splitpro handle settle up? is it "just" a new balance with the exact amount missing which gets entered into the database, or do balances have a boolean for settled up.

The biggest problem I see with changing the the exchange rate is that previous settled balances could become unsettled.
So do we need 2. at all?
If every transaction automatically stores its conversion rate into your default/preferred currency at the time you add them, balances could just use that and there wouldn't really be a need to convert them.

(maybe have a dropdown next to the balance which lists the the remaining amount divided according to the individual currency balances and the average conversion rate in each case - that would probably be a bit overkill though).

[krokosik]

Settleups are treated as a type of expense (money transfer) and I imagine currency conversions being treated in the same way. Each expense has associated transfers occuring, for (person A receiving X from B) and we can assign two transfers in different currencies to a currency exchange expense.

[Silther]

A thing I completely missed before, what if two people have different preferred currencies, the currency conversion would have to happen on a per user bases.