BaseX-Talk

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1 participants
5252 discussions

COPY DB vs. CREATE DB
by Jonathan Robie 16 Feb '22

16 Feb '22

What's the easiest way to copy a database, whether or not there is an existing copy with a given name? If I load a database with CREATE DB, it replaces any existing database with the same name. I would like to do the same with COPY DB, but it raises an error if there is a database with the same name. And DELETE DB raises an error if there isn't a database with that name. So what's the right way to do this? Jonathan

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Accessing Java constant from XQuery
by Paul L. Merchant Jr. 16 Feb '22

16 Feb '22

Hi everyone, I'm using a Java library in XQuery in BaseX and I haven't been able to determine if there's a way to access a constant string (final static String... or even just final String...) in the Java class from XQuery. For example, if the Java class is declared as package my.module; public class MyModule { public static final String TITLE ="I'm a module!"; public String hello(final String world) { return "Hello " + world; } } The XQuery to call the "hello" method is import module namespace java = 'java:my.module.MyModule'; java:hello("World!") But is there any way to access "TITLE"? I'd like to share some constants between XQuery and Java, and I could write accessor functions for these constants, but it'd be cleaner if I didn't have to. Thanks!

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fn:format-date french translation
by Josselin Morvan 16 Feb '22

16 Feb '22

Hi everyone! It seems that there is no french translation for the fn:format-date() fonction with BaseX. Does anyone knows how and where I could add it to make it run with the format-date() function? Eventually, I could share the translation to make it accessible to all? Thanks a lot for your help, Best, Josselin

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Best Technique for Managing Sequences of Transactions Through Web/REST App
by Eliot Kimber 15 Feb '22

15 Feb '22

My validation dashboard is coming together and I’m now at the point of moving data update orchestration into the web app itself, rather than just in the shell scripts and single-transaction XQuery scripts I have now. My question is: What is the recommended technique, or what are the available options, for orchestrating a sequence of transactions in the context of a web application? For example, I have a button, not yet implemented, that needs to trigger update or creation of one of my indexes, which involves several transactions (drop temporary work database if it exists, create new work database, do work in that database, swap work result with current production database). I know I can use a sequence of redirects to get this and of course could also orchestrate it through JavaScript running in the browser. I’m trying to avoid JavaScript in this application simply to avoid complexity and keep as much of it as possible in XQuery. I’m also trying to work out the best way to present status and feedback for long-running actions—I know how to do the javaScript programming for this but again I’m hoping I don’t have to step up to that level of sophistication, at least not yet. So curious what techniques people use or recommend for transaction orchestration and monitoring. Thanks, Eliot _____________________________________________ Eliot Kimber Sr Staff Content Engineer O: 512 554 9368 M: 512 554 9368 servicenow.com<https://www.servicenow.com> LinkedIn<https://www.linkedin.com/company/servicenow> | Twitter<https://twitter.com/servicenow> | YouTube<https://www.youtube.com/user/servicenowinc> | Facebook<https://www.facebook.com/servicenow>

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'Flatten' a collection
by Ben Engbers 14 Feb '22

14 Feb '22

Hi, I have a collection of 740 XML-documents which I want to flatten. The files all have the same structure: <handeling id="h_1"> <datum date="d_1"/> <spreekbeurt><spreker>spreker_1</spreker></spreekbeurt> <spreekbeurt><spreker>spreker_3</spreker></spreekbeurt> </handeling> <handeling id="h_2"> <datum date="d_2"/> <spreekbeurt> <spreker>spreker_2</spreker></spreekbeurt><spreekbeurt> <spreker>spreker_1</spreker><spreekbeurt> <spreker>spreker_4</spreker></spreekbeurt> </handeling> <handeling id="h_3"> <datum date="d_3"/> <spreekbeurt><spreker>spreker_2</spreker></spreekbeurt> <spreekbeurt><spreker>spreker_3</spreker></spreekbeurt> <spreekbeurt><spreker>spreker_2</spreker></spreekbeurt> <spreekbeurt><spreker>spreker_1</spreker></spreekbeurt> </handeling> The following query gives this result: import module namespace functx = "http://www.functx.com"; let $Blogs := collection("Blog") let $Turns := collection("Blog") for $Blog in collection("Blog"), $Turn in collection("Blog") where $Turn//datum/@date = $Blog//datum/@date order by $Blog//datum/@date count $Count let $Id := $Blog/handeling/@id let $Datum := $Blog//datum/@date let $Speaker := $Turn//spreker/text() return($Id, $Datum, $Speaker, $Count) id="h_1" date="d_1" spreker_1 spreker_3 1 id="h_2" date="d_2" spreker_2 spreker_1 spreker_4 2 id="h_3" date="d_3" spreker_2 spreker_3 spreker_2 spreker_1 3 But what I eventually need is this (for clarity shown as a table): 1, id="h_1", date="d_1", 1, spreker_1 1, id="h_1", date="d_1", 2, spreker_3 2, id="h_2", date="d_2", 1, spreker_2 2, id="h_2", date="d_2", 2, spreker_1 2, id="h_2", date="d_2", 3, spreker_4 3, id="h_3", date="d_3", 1, spreker_2 3, id="h_3", date="d_3", 2, spreker_3 3, id="h_3", date="d_3", 3, spreker_2 3, id="h_3", date="d_3", 4, spreker_1 The first counter indicates the position in $Blog. and the second counter indicates the position in $Turn I expected that the following query would return what I was looking for: for $Blog in collection("Blog") order by $Blog//datum/@date let $Id := $Blog/handeling/@id let $Datum := $Blog//datum/@date count $countOuter return ( for $Turn in collection("Blog") where $Turn//datum/@date = $Blog//datum/@date let $Speaker := $Turn//spreker/text() return ($countOuter, $Id, $Datum, $Speaker)) Instead it returns 1, id="h_1", date="d_1", 1, spreker_1, spreker_3 2, id="h_2", date="d_2", 1, spreker_2, spreker_1, spreker_4 3, id="h_3", date="d_3", 1, spreker_2, spreker_3, spreker_2, spreker_1 I have 2 questions: 1: Is it possible to use separate counters for the inner and the outer loop? (How should I define the $countInner?) 2: How can I formulate the query for getting the correct output? Ben Engbers

4 3

combining queries from mutiple sources
by Eric Levy 14 Feb '22

14 Feb '22

I am completely new to BaseX, and trying to conceive of a way to use it to process a compound query that combines an external query with a static one. The core idea is a very simple application, expressed as an XQuery file, that results in the following sequence of actions: 1. Extraction of data from a database, by some query. 2. Modification of the results of (1), by some query. 3. Persistence of the results from (2), back into the database from which the data was originally extracted. The modifications given in (2) would be expressed external to the application, supplied as input per invocation, in a separate file or in a command-line parameter. Thus, the overall operation would entail static components, the fixed parts of the application, represented by (1) and (3), and dynamic components, passed by the invocation, represented by (2). I realize such a processing pipeline may be achieved through queries supplied in a full application accessing the database by one of the language-specific APIs, but I am trying to consider an approach that requires use only of XQuery statements, without involving a separate programming language or formal build process. Does the design of BaseX accommodate an application having the structure as described?

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Feature request - file listing
by Hans-Juergen Rennau 12 Feb '22

12 Feb '22

Dear BaseX people, I have a feature request: a function which does the same as file:list, but returns the full paths. (In the explanation, I call it "file:list2") Rationale: (a) It is the full paths what we need in order to parse the files (doc(), json:doc(), csv:doc(), html:doc()). (b) The combination of file listing and parsing in a single expression is of matchless elegance and expressivenessJust think about how we can extend this into a single list+parse+navigate+report expression, like: file:list2($folder, true(), $fname) ! doc(.) ! //returnCode[. ne 0]/concat(base-uri(.), ': ', .) (Wow! Is there any language or tool competing with this compactness and readability?) Currently, if I don't overlook something, I have to do this: file:list($dir, false(), $fname) ! concat($dir, '/', .) ! doc(.) => count() I emphasize the psychological aspect. Every time I have the pleasure to give a workshop about XQuery, I show off how elegant it is to parse a whole file system tree into a forest of nodes in a single expression. And I am always embarrassed about this clumsy fumbling montage of a path. It's as if Mozart had fallen asleep while writing his xquery sonata, knocked over the inkwell and now there is this splash smeared out on the score. You would be my heroes if you can spare us that. Kind regards,Hans-Jürgen

6 9

my application's performance statistics
by Rob Stapper 11 Feb '22

11 Feb '22

Hi Christian, I did some performance statistics on my application and something caught my eye, which I hope you can shed some light on. I found that when running the application the distribution of the life-cycle fases: Parsing, Compiling, Evaluating and Printing, is: Parsing : 95%, Compiling : 4%, Evaluating : 0.4% and Printing : 0.03% . My development-paradigm is maintainability and not as much as performance optimization. So I expect is a lot of code-optimization during parsing and therefore a relatively high amount of time consumed for parsing. This is confirmed by the relatively low amount of time for the Compiling- and Evaluating-time. Code-optimization actually is a strong point of the parser. However I had expected/hoped that this code-optimization only occurs at the first run and that the optimized code is kept for following runs. This does not seem to be the case. First of all: am I correct in my analysis? Secondly, can you give me any advise on improving the parsing-time, not being giving up on my development-paradigm, based on these stats? Some more stats: The info-view gives for the compiling -fase a total of 2124 lines of which: - Inline …… 923 lines - Remove type check …. 710 lines - Simplify FLWOR …. 218 lines - Rewrite … 150 lines - Unroll …. 12 lines - Merge: concat ….. 11 lines - Open database … 3 lines - Swap operant … 1 lines - Simplify catch * …. 4 lines - Thnx in advance for your reply. Rob Stapper Sent from Mail for Windows -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

2 1

file:descendants - returns relative paths
by Hans-Juergen Rennau 11 Feb '22

11 Feb '22

Dear BaseX people, functions file:children() file:descendants() should return the full paths of the resources found, but they do so only if the argument was in turn a full path. A bug? Example: file:children('.') =>PS C:\projects\xquery-introduction\tips> basex "file:children('.')" .\foo.xq .\bar.docx Kind regards,Hans-Jürgen

2 1

How to extract value from fn:analyze-string
by Ben Engbers 11 Feb '22

11 Feb '22

Hi, This query produces the following result: let $debates := collection("Parliament") for $debate-item in $debates let $item-file := $debate-item/officiele-publicatie//meta/@content let $debate-id := fn:analyze-string( $debate-item/officiele-publicatie//meta/@content, "(\d{8}-\d*)-(\d*)") return ($debate-id) => <analyze-string-result xmlns="http://www.w3.org/2005/xpath-functions"> <non-match>https://zoek.officielebekendmakingen.nl/h-tk-</non-match> <match> <group nr="1">20202021-102</group>-<group nr="2">1</group> </match> <non-match>/metadata.xml</non-match> </analyze-string-result> ... I am trying to extract the values from group 1 and 2 but this query returns 0 results: let $debates := collection("Parliament") for $debate-item in $debates let $item-file := $debate-item/officiele-publicatie//meta/@content let $debate-id := fn:analyze-string( $debate-item/officiele-publicatie//meta/@content, "(\d{8}-\d*)-(\d*)") let $debate-nr := $debate-id//match/group[@nr="1"]/text() let $item-nr := $debate-id//match/group[@nr="2"]/text() return ($debate-nr, $item-nr) My guess is that analyze-string inserts new elements in the query and that that is the reason why this does not work. How can I extract debate-nr and item-nr from $debate-id? Ben Engbers

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