Hi Markus, you wrote

"How would you determine where unexpected gaps occur?"

Gaps? First, to avoid a misunderstanding: whereas map keys must not be the empty sequence, map values may.

An elegant way to construct map entries safely - taking care that the key is not empty - is to use the map operator (!) or a path step, in both cases with the map:entry() on the right-hand side.

Example, map operator:

$thingy/@name/normalize-space(.)[string()] ! map:entry(., $tingy/string())

Example, path step:

map:merge(doc('things.xml')//thingy/@name[normalize-space(.)]/map:entry(., ../string()))

Kind regards,

Hans-Jürgen

Am Freitag, 27. Mai 2022, 10:51:00 MESZ hat Markus Elfring <markus.elfring@web.de> Folgendes geschrieben:

> although I do not quite understand your description

Which wording variant would you have found clearer for the mentioned use case?

> (why should I care for the representation of the map I construct?),

* Selection of a general data structure for the handling of key/value pairs

* I guess that you would like to put customised data into keys and associated values.

> it may be that one piece of information is useful to you,

Thanks for your constructive feedback.

> as it is not obvious from the spec: it's about how to construct a map dynamically,

Can such a view trigger any further consequences?

> that is,
>
> (1) when the keys are not known beforehand,
> (2) and/or when the entry values are assigned in "iterations" of a FLWOR expression
>
> (Especially (2) might be what puzzles you.)

I thought also about this data processing area in special ways for a moment.

> (1) and (2) can't be accomplished when using the map constructor expression, like this: basex "map{'x':1, 'y': false()}"

Will any information sources help to understand this technical detail better
(besides the XPath function library)?

> The trick consists of using a combination of the functions map:merge() [1] and map:entry() [2].

I became curious how application considerations will evolve further.

> This code may for example be (most often is) a FLWOR expression.
> In this code, each entry is constructed by a call of function map:entry().

Now I stumble on the error message “[XPTY0004] Item expected, empty sequence found.”
from my software test according to a special data source.
How would you determine where unexpected gaps occur?

Regards,
Markus