helper:assert-throws-error, xdmp:apply, varargs

[kefo]

I have a function I want to test.  It takes 6 parameters.  If I call helper:assert-throws-error, I get a “Too few args” error message.  The error is actually occurring at line 295.

I think this might be a bug because xdmp:apply seems to require the $params be itemized.  Instead of this

    let $params := (‘1’, ‘2’, ‘3’)
    return xdmp:apply( $func, $params )

You seem to have to do this:

    let $params := (‘1’, ‘2’, ‘3’)
    return xdmp:apply($func, $params[1], $params[2], $params[3])

(Side note: Some googling turned up this 2011 post discussing the ‘varargs’ aspect of xdmp:apply.)

I’ve actually implemented a fix locally and it seems to work. Of course, it has all ugliness mentioned in the above post. Happy to submit a pull request if, in fact, this is an issue.

If it isn’t an issue, please advise how one uses helper:assert-throws-error with multiple vars.

[grtjn]

I think you found the best solution for the moment, though I wonder if you need to distinguish between all numbers of args like in the 2011 post. That link also proposes to use map:map to pass through arguments, which solves passing through sequences as argument. Or perhaps json:array would be practical here. Definitely a bug..

[grtjn]

Fixed in dev..

[ghost]

This is not actually working from what I can tell. There are 2 problems that i see, one is that the way the cascade of function calls are built, it will not work with <6 parameters. What ends up happening is that all sample functions get called with 6 parameters, with the balance being the empty sequence.

Once that was corrected, I noticed a different problem/limitation in json:to-array. There is some sequence collapse processing happening somewhere in the call stack that shouldn't be. This problem can be seen with this: json:to-array(json:to-array(1)) which should yield [ [ 1 ] ] but actually yields [ 1 ]. Luckily there is a way to workaround this by doing json:to-array((json:to-array(1), json:to-array('xtra')), 1)

See attached patch for a fix:
refactored-json-array-patch.txt

I can make a pull-request if that is helpful, but didn't seem necessary for such a small diff.

[ghost]

Hmm, not sure my patch is correct... I think sending an empty sequence to an XQuery function as an argument in this case the function will receive an empty JSON array instead... I need to double check that when I get a chance.

UPDATE: Nevermind, I think it is OK after all. The json:array-values() does seem to work correctly to convert an empty json array into an empty sequence. The only trouble would come in if you tried to test a function with arrity > 6 and also sent some arguments as empty-sequence and it hit the fallback statement.

[grtjn]

:)

Feel free to reopen again, or file a new ticket if you think those edge cases can be a real issue..