First, thank you for this incredible lib.

Second: I'm new to Rust and spinning up my first backend (DB + Webserver), so please feel free to redirect me other places if I can answer my own questions.

Problem

While the Postgresmoney type isspecified in postgres-types, it doesn't appear to haveimpl To/FromSql out of the box. I tried using floats and ints to convert, with no luck - lots of errors likecannot convert between the Rust type i32 and the Postgres type money. I could implement these myself, but I wonder if they are simple enough to include in the library (if not by default, then perhaps as a feature).

From what I can tell from thePostgres docs on Monetary Types,it appears as though themoney type is likely represented as an i64 of cents.

Rationale:

• Postgres docs list a range of -92233720368547758.08 to +92233720368547758.07. If you take the high number, you'll notice that it is (2^63)-1 / 100. So it seems like a good bet that Postgres is modeling the cents under the covers, but "rendering" in dollars.

Proposed Code Change

• AddMONEY to thesimple_from! andsimple_to! entries fori64 in src/lib.rs:

(Line563)simple_from!(i64, int8_from_sql,INT8,MONEY);(Line889)simple_to!(i64, int8_to_sql,INT8,MONEY);

I made this change to my local cargo lib, and was able to run a query against amoney Postgres column and serialize it into an i64 struct field successfully. I have not tested the reverse path, going from Rust i64 to PG money column.

Snippets of the struct, impl, and Postgres table below:

pubstructAccount{id:Uuid,name:String,balance:i64,}implFrom<Row>forAccount{fnfrom(row:Row) ->Self{Self{id: row.get("id"),name: row.get("name"),balance: row.get("balance"),}}}

<localhost>=# \d accounts;                           Table"public.accounts" Column  |         Type          | Collation | Nullable |      Default---------+-----------------------+-----------+----------+-------------------- id      | uuid                  |           |not null | uuid_generate_v4() name    |character varying(40) |           |not null | balance |money                 |           |not null |0

Open Questions:

• Is the macro the correct approach, or shouldmoney get it's own explicit impl?
• Is this a common enough conversion to include by default, or should it be a feature?
• From the Postgres docs: "The fractional precision is determined by the database's lc_monetary setting." This seems like it could cause some wackiness.
• Further investigation would have to be done to ensure the conversion from Rust -> PG works as expected.
• Is i64 a good way to model money?