Render CastingExpression as "cast" function in PostgreSQL dialect

[arustleund]

Can the CastingExpression be rendered in PostgreSQL thusly?

    override fun <T : Any> visitCasting(expr: CastingExpression<T>): CastingExpression<T> {
        write("cast(")
        super.visit(expr.expression)
        removeLastBlank()
        write(" as ")
        write(expr.sqlType.typeName)
        write(") ")
        return expr
    }

Or is this not the intention of this expression?

[vincentlauvlwj]

CastingExpression was originally design just to make Kotlin's type checking happy, and it doesn't influence the generated SQL.

Assuming we want to join two tables together, in which one has an int id and the other has a long id:

object T1 : Table<Nothing>("t1") {
    val id by int("id")
}

object T2 : Table<Nothing>("t2") {
    val id by long("id")
}

We might write code like this:

database.from(T1).leftJoin(T2, on = T1.id eq T2.id)

Then the compiler complains that the types of these two ids are not matched. We have to modifiy it as follows:

database.from(T1).leftJoin(T2, on = T1.id.toLong() eq T2.id)

Just a trick.

[vincentlauvlwj]

I just read the document of PostgreSQL's cast function. It will be great to actually generate a cast function in SQL.

[d35h]

Hello,

any update on this one?

I'd be interested in this function too :)