Add get_decimal()

[M5135213521asd3]

Get cassadra decimal value as BigDecimal (https://docs.rs/bigdecimal/latest/bigdecimal/)
Signed-off-by: Marian Marencik github@marianm.net

[M5135213521asd3]

Signed-off-by: Marian Marencik github@marianm.net

[kw217]

Thanks @M5135213521asd3 , this looks good. Just a couple of things:

• Please can you ensure you return the actual error, rather than a fixed one.
• I think this must be missing the code to supply a decimal value to Cassandra (i.e., bind). Please can you add that?
• Please can you add a decimal test in all the relevant places, to tests/basic.rs? Use a value that requires multiple bytes and a non-zero scale, so that the code is properly exercised.
• Please can you also add a specific test for endianness (to the same file), which uses a literal CQL statement to write a decimal value (e.g., INSERT INTO blah ... VALUES (99999.1234)), and then uses get_decimal to retrieve it and checks it gets the right value?

Thanks!

[M5135213521asd3]

• I think this must be missing the code to supply a decimal value to Cassandra (i.e., bind). Please can you add that?

I have include it to this request, but from my side there is one todo:

//@TODO: cpp scale = i32, BigInt scale = i64
        unsafe {
            cass_statement_bind_decimal(
                self.inner(),
                index,
                varint.as_ptr(),
                varint.len(),
                **scale as i32,**
            )
            .to_result(self)

[kw217]

Thank you very much! This is looking great! I have a suggestion for how to deal with your remaining TODO; otherwise this is fine!

[kw217]

Thanks! I think it's highly unlikely anyone will be using 4GB BigInts, but just in case, you should convert scale using try_into() and then if it fails return an error. I think it's OK to reuse one of the CASS_ERROR_LIB errors here, even though that's not strictly accurate: probably CASS_ERROR_LIB_INVALID_DATA.

[kw217]

As above.

[kw217]

LGTM! Thanks!