Clojure Q&A - Recent questions tagged clojure.data.xml

Default implementation of AsElements to treat numbers as numbers, not strings

Tue, 28 Apr 2026 16:10:26 +0000

I'm slowly converting some code from using xml/element to xml/sexp-as-element, and I've noticed a discrepancy. xml/element does (almost) no processing of the "content", inserting it directly (unless it's nil). xml/sexp-as-element calls (str) on the "content" if it's not seq of some kind (vector or ISeq) or a keyword. This means that (= (xml/element :foo {} 1) (xml/sexp-as-element [:foo 1])) is false.

There are probably other differences, but this one seems relatively big, as there's no way to use numbers in xml/sexp-as-element without calling extend-protocol yourself.

May I recommend/request adding this extension? It will make xml/sexp-as-element match xml/element for numbers, and make xml/sexp-as-element match hiccup in general.

(extend-protocol clojure.data.xml.protocols/AsElements
  java.lang.Number
  (as-elements [n] [n]))

clojure.data.xml/aggregate-xml generates invalid "xml" and "xmlns" prefixes

Wed, 22 Feb 2023 22:37:19 +0000

Using aggregate-xmlns with larger xml trees causes the following exception:

Execution error (ExceptionInfo) at clojure.data.xml.name/legal-xmlns-binding! (name.cljc:151).
The xmlns binding for prefix `xml` is fixed to `http://www.w3.org/XML/1998/namespace`

aggregate-xmlns creates a new prefix for each tag with gen-prefix:

     (binding [*gen-prefix-counter* 0]
       (-> (fn [tm uri]
             (pu/assoc! tm (gen-prefix) uri))
           qname-uri-xf
           (reduce-tree (pu/transient pu/EMPTY) xml)
           pu/persistent!))}))

gen-prefix itself just deterministically joins characters to make up a new prefix string, e.g. "a", "b", "c" ...

Unfortunately the 7771th iteration generates the prefix string "xml", which is illegal to use and is rejected in clojure.data.xml.pu-map/assoc! by the check in (name/legal-xmlns-binding! prefix uri), causing the above quoted exception. The same problem will happen later for "xmlns".

An easy workaround is to not do the checks in case the uri is blank.

clojure/data.xml tests fail on JDK 17

Sun, 06 Feb 2022 18:20:42 +0000

Hi,

The clojure/data.xml test suite fails to run on JDK 17 with the following error

$ lein test
Exception in thread "main" Syntax error compiling at (clojure/data/xml/cljs_repls.clj:11:5).
	at clojure.lang.Compiler.analyze(Compiler.java:6808)
	...
	at clojure.main.main(main.java:37)
Caused by: java.lang.RuntimeException: No such var: repl-nh/eval-resource
	at clojure.lang.Util.runtimeException(Util.java:221)
	at clojure.lang.Compiler.resolveIn(Compiler.java:7387)
	at clojure.lang.Compiler.resolve(Compiler.java:7357)
	at clojure.lang.Compiler.analyzeSymbol(Compiler.java:7318)
	at clojure.lang.Compiler.analyze(Compiler.java:6768)
	... 67 more
Tests failed.

This is because the Clojurescript tests run on top of the Nashorn JS engine, but the latter has been removed from JDK 15 onwards.

Are there any plans to run the tests directly from Clojurescript, perhaps as core.async does it with deps.edn? Happy to have a look if so and you are open to PRs.

Thanks