BaseX-Talk November 2017

basex-talk@mailman.uni-konstanz.de

27 participants
44 discussions

BaseX scripting
by Kristian Kankainen 28 Nov '17

28 Nov '17

A simple question - did I correctly understand, that when running a script, then each separate command will be an isolated transaction? And that it is not the case that the whole script is treated as a single transaction? So that, let's say I have script with three updating commands (or XQueries) A, B and C. While running it, A and B executes successfully but C creates an error. After running the script, whatever was updated by A and B is still reflected in the database? Br, Kristian

2 2

id generation and updates
by E. Wray Johnson 27 Nov '17

27 Nov '17

How can I white a single XQUERY statement that assigns an auto-generated id to a node (using either generate-id(), or random:uuid() ) then inserts the node into a database and then returns the auto-generated id. I can do the id assignment and insert operation just fine using { }, I just don't know how to return the id afterward

3 7

Issue preserving namespaces with json:parse
by E. Wray Johnson 24 Nov '17

24 Nov '17

What is wrong with this code? import module namespace geo = 'http://expath.org/ns/geo'; declare namespace gml='http://www.opengis.net/gml'; let $opt := map { "lax": true() } let $y := json:parse('{ "coords":{ "gml:Point":{ "gml:coordinates":"0,0" } } }', $opt ) let $x := json:parse('{ "coords":{ "gml:Point":{ "gml:coordinates":"-123.45,45.343" } } }', $opt ) return geo:distance($x/json/coords/*, $y/json/coords/*)

2 3

Unknown function: lazy:cache
by Bridger Dyson-Smith 21 Nov '17

21 Nov '17

Hi Christian, et al, In the process of reading the wiki and trying examples, I've stumbled across a problem while attempting the lazy:cache example[1] let $f := 'lazy.txt' let $t := lazy:cache(file:read-text($f)) return(file:delete($f), $t) throws an error "No namespace for 'lazy:cache'." If I prepend a `declare namespace lazy = "http://basex.org/modules/lazy";` to the beginning of my test file, I get an updated error: "Unknown function: Q{ http://basex.org/modules/lazy}cache". I get that same result in BaseX-latest (9.0 beta b5f1824) and v8.6.7. Is this a bug or is this A Case of The Missing Import Module Statement? Thanks in advance for your help. Cheers, Bridger [1] http://docs.basex.org/wiki/Lazy_Module#lazy:cache

2 1

Loading data
by E. Wray Johnson 20 Nov '17

20 Nov '17

I have a JSON file https://gist.githubusercontent.com/Miserlou/c5cd8364bf9b2420bb29/raw/2bf258… I want to load it into a database in a different XML format where I can use gml:Point in place of longitude and latitude as separate elements. However my for loop does not emit individual XML elements for each json object in the loaded array.

3 7

geo package - Great Circle Distances
by E. Wray Johnson 20 Nov '17

20 Nov '17

Can anyone recommend how in BaseX to calculate great circle distances (e.g. between two geo:Points) (e.g. in meters or kilometers).

1 0

Documentation typo
by Marco Lettere 20 Nov '17

20 Nov '17

Hi all, I think there is a typo in the documentation on the map:merge function [1]. The Summary states the possibility to use "use-combine" as a value for duplicates option but it should be 'combine' only. Regards, M. [1] http://docs.basex.org/wiki/Map_Module#map:merge

2 1

Re: [basex-talk] Spatial Reference not working
by Christian Grün 18 Nov '17

18 Nov '17

The Geo Module is basically a light-weight wrapper for the JTS Topology Suite: geo:srid calls getSRID() (see [1]). Maybe you could ask on the jts mailing list and give us some feedback? [1] https://github.com/BaseXdb/basex/blob/master/basex-api/src/main/java/org/ex… Am 14.11.2017 12:23 vorm. schrieb "E. Wray Johnson" <wray.johnson(a)gmail.com >: I am sorry, I did not make myself clear. It always returns 0. There is a way to set the spatial reference. Typically with the srsName attribute on the geometry. In this example that would be the gml:Polygon element. However, none of the valid values is recognized by JTS. It is as if the srsName attribute is not getting to JTS. On Mon, Nov 13, 2017 at 5:41 PM, Christian Grün <christian.gruen(a)gmail.com> wrote: > > I can’t get the geo:srid() to work. I have tried many combinations of > @srsName values. Can anyone provide examples? > > Try e.g. this: > > import module namespace geo='http://expath.org/ns/geo'; > declare namespace gml='http://www.opengis.net/gml'; > geo:srid( > <gml:Polygon> > <outerboundaryIs> > <gml:LinearRing> > <coordinates>-150,50 -150,60 -125,60 -125,50 > -150,50</coordinates> > </gml:LinearRing> > </outerboundaryIs> > </gml:Polygon> > ) >

2 4

Re: [basex-talk] XPath generator
by Kristian Kankainen 17 Nov '17

17 Nov '17

I don't know if it is the optimal solution in BaseX, but what functionality concerns, you can look at this functx function: http://www.xqueryfunctions.com/xq/functx_path-to-node-with-pos.html For BaseX specifics, maybe this page can help you (sorry but I am not sure): http://docs.basex.org/wiki/Index Best, Kristian K17. nov 2017 4:06 PM kirjutas kuupäeval Giuseppe Celano <celano(a)informatik.uni-leipzig.de>: > > Hi All, > > I would like to ask what the best way is in BaseX to create XPath expressions once I identify a certain span in an XML file. More concretely, I usually tokenize a text contained in an XML document, and I would like to specify for each token its position in the original document. Thanks. > > Best, > Giuseppe > >

1 0

Some string peculiarities
by Kristian Kankainen 17 Nov '17

17 Nov '17

Hello I encountered some strange things when tokenizing text. Sample runnable code is added below. Here is my list of problems: 1) the regular expression "(\.){3}" doesn't match the same as "(\.\.\.)". Shouldn't they be equal? 2) a very annoying whitespace is placed text to the newline of out:nl(). It is placed before out:nl() if it is called in the beginning of an element, or it is placed after the newline if out:nl() is called in the end of an element. E.g the serialized output is either "<s> this" or ". </s>". Sample runnable code: for $text in ("this one... is the first.", "this one is second.") return <s>{ out:nl(), string-join( analyze-string($text, '(\.){3}|[\W]')//text()[not(.=" ")], out:nl() ), out:nl() }</s> , "--------- VERSUS --------- " , for $text in ("this one... is the first.", "this one is second.") return <s>{ out:nl(), string-join( analyze-string($text, '(\.\.\.)|[\W]')//text()[not(.=" ")], out:nl() ), out:nl() }</s>

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BaseX-Talk November 2017