Optic api 如何在列表中的位置执行操作？

Question

I have the following XQuery code that uses op:from-view . In the op:where section I am trying to select a column that can equal a list of values. When I use one value like op:eq(op:col("client"), $client1) it works fine. However i need it to select ($client1, $client2) . How do I do that? I can't seem to find an example anywhere. Thanks.

Answer 1

Optic doesn't have an in() operator at present, so the condition would have to be passed to Optic as

op:or((op:eq(op:col("client"), $client1), op:eq(op:col("client"), $client2)))

To make that less tedious, one possibility would be to take advantage of build-time expressions as in:

op:or(
    let $col := op:col("client")
    for $val in ($client1, $client2)
    return op:eq($col, $val)
    )

Or to wrap that expression in a helper function:

declare function local:in($colName as xs:string, $vals) {
    op:or(
        let $col := op:col($colName)
        for $val in ($vals)
        return op:eq($col, $val)
        )
};

and use it as follows:

op:where(
    local:in("client", ($client1, $client2))
    )

Hoping that helps,