Hi, how can i make that query? ```fun distance( ...

# exposed

[João Eudes Lima]

Hi, how can i make that query?

fun distance(
    lat: Double,
    lon: Double,
    latColumn: Expression<Double>,
    lonColumn: Expression<Double>
) {
    val radius = PI / 180
    val radiusLiteral = doubleParam(radius)
    val radLat = doubleParam(lat * radius)     // Precomputed latitude in radians
    val radLon = doubleParam(lon * radius)     // Precomputed longitude in radians
    val earthRadiusKmLiteral = doubleParam(6371.0)     // Earth radius in kilometers

    Expression.build {
        acos(
            cos(radLat) *
            cos(latColumn * radiusLiteral) *
            cos((lonColumn * radiusLiteral) - radLon) +
            sin(radLat) *
            sin(latColumn * radiusLiteral)
        ) * earthRadiusKmLiteral
    }
}

[Chantal Loncle]

Hi @João Eudes Lima Existing trig and math functions require ExpressionWithColumnType (like actual columns and doubleLiteral()), as do most infix operators. These built-in trig functions also use DecimalColumnType under the hood.

So if you want to be using specifically un-column-typed expressions with doubleParam(), you can implement less restrictive versions in any way you want. For example, I've chosen to not use extension functions below for more readability:

fun <T : Double?> acos(expr: Expression<T>): CustomFunction<Double?> =
    CustomFunction("ACOS", DoubleColumnType(), expr)
fun <T : Double?> cos(expr: Expression<T>): CustomFunction<Double?> =
    CustomFunction("COS", DoubleColumnType(), expr)
fun <T : Double?> sin(expr: Expression<T>): CustomFunction<Double?> =
    CustomFunction("SIN", DoubleColumnType(), expr)

infix operator fun Expression<Double>.times(other: Expression<Double>): TimesOp<Double, Double> = TimesOp(this, other, DoubleColumnType())

Then your final block above would look like this:

acos(
    cos(radLat)
        .times(cos(latColumn * radiusLiteral))
        .times(cos((lonColumn * radiusLiteral) - radLon))
        .plus(sin(radLat))
        .times(sin(latColumn * radiusLiteral))
) * earthRadiusKmLiteral

[João Eudes Lima]

Thanks @Chantal Loncle