Hi Markus,
although I do not quite understand your description (why should I care for the
representation of the map I construct?), it may be that one piece of
information is useful to you, as it is not obvious from the spec: it's about
how to construct a map dynamically, 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.)
(1) and (2) can't be accomplished when using the map constructor expression,
like this: basex "map{'x':1, 'y': false()}"
The trick consists of using a combination of the functions map:merge() [1] and
map:entry() [2].
So summarize, the code constructing the map entries is the argument of function
map:merge().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(). For a
tiny example see below.
Kind regards,Hans-Jürgen
PS: Tiny example demonstrating the construction of maps via map:merge() &
map:entry().
(: Creates a map with one entry for each element name encountered in the
input document. The entry value is the number of elements with that name. As
the map keys are not known in advance, map:merge() is used. :)map:merge(
for $elem in //* group by $name := $elem/local-name(.) return
map:entry($name, count($elem)))
[1] https://www.w3.org/TR/xpath-functions-31/#func-map-merge[2]
https://www.w3.org/TR/xpath-functions-31/#func-map-entry
Am Mittwoch, 25. Mai 2022, 16:59:48 MESZ hat Markus Elfring
<markus.elfr...@web.de> Folgendes geschrieben:
Hello,
I would like to construct a map structure based on a dynamic selection by
the means of a FLWOR expression.
https://www.w3.org/TR/2017/REC-xquery-31-20170321/#id-maps
The keys and associated values should be presented as a CSV-like file by
a subsequent data processing step.
Can it become easier to find existing XQuery script examples for such an use
case?
Regards,
Markus
