Deriving types for QueryResult Records (and the Option of)

[tobyweston]

As the query results are Any, how do you suggest deriving types for the values?

For example:

val temperature: Double = record("temperature").asInstanceOf[BigDecimal].toDouble

but that seems nasty. Do you retain the type from the JSON wire format? Any fancy implicit encoders available?

Similarly, how do you advice handling values which may be not there, e.g.

val maybeTemperature: Option[Double] = record("maybeThere") ...

Would be nice, but as it stands I can get NoSuchElementException when I request something that isn't there.

I had a poke around but couldn't find anything obvious.

Thanks in advance

[paulgoldbaum]

@tobyweston, in the first case I'm not sure what a good solution could look like, as these types can be different for each row. Maybe we could add type parameters to the query for when you know the types in advance and just fail the query if one row doesn't match. What do you think?

And yes, records should return Options instead of throwing an exception. Right now you can only surround it with a try-catch.

[tobyweston]

Yeah, that's the best I can think of, something like:

val temperature: Double = record("temperature")

Where Double should be enough for an implicit conversion method to kick in?

def toDouble(any: Record): Double = any.asInstance[BigDecimal].toDouble // with some error handling

or maybe

def toDouble(any: Record): Option[Double] = {
    Try(any.asInstance[BigDecimal].toDouble).toOption
}

to handle the error and absence of the value at the same time?

I don't know if there are other constraints within the codebase that make implicits not a good option but from a client API perspective, i'd certainly prefer not to have to care how types are pulled back. I haven't tried it yet so hypothetical ATM 👍