marcinwieckowski opened a new pull request, #25843:
URL: https://github.com/apache/camel/pull/25843
# Description
Adds a `namespacesRef` attribute to `NamespaceAwareExpression` (the shared
base class for
`XPathExpression`, `XQueryExpression` and
`XMLTokenizerExpression`/xtokenize), letting users
reference a registry bean instead of declaring namespaces inline.
**Why**: today, namespace-aware languages only support namespaces declared
inline via
`<namespace>` child elements (or programmatically via a `Map`/`Namespaces`
object in Java DSL).
There is no way to define a reusable set of namespace mappings once and
reference it by name
from multiple expressions/routes, which becomes repetitive for XML payloads
with many
namespaces reused across a route's XPath conditions.
**How**:
- `namespacesRef` is a plain string attribute (bean id) on
`NamespaceAwareExpression`, marked
`@Metadata(label = "advanced")`, and inherited by XPath, XQuery and
Xtokenize.
- Each reifier (`XPathExpressionReifier`, `XQueryExpressionReifier`,
`XMLTokenizerExpressionReifier`) resolves the namespaces in
`createProperties()`, i.e.
**before the language builds the expression**, via a private
`resolveNamespaces()`. If no
inline namespaces are present, the bean is looked up with
`mandatoryLookup(ref, Namespaces.class)` - intentionally typed to
`org.apache.camel.support.builder.Namespaces`, the same class used in Java
DSL for xpath
namespaces - and the result is passed through `parseMap()` so property
placeholders resolve.
- Resolving before the expression is built (rather than afterwards via
`configureExpression`/`configurePredicate`) is required for Saxon, which
resolves prefixes at
compile time; injecting namespaces after the fact fails with "Namespace
prefix has not been
declared". This is what blocked the earlier attempt in #25561.
- Inline `<namespace>` elements still take priority when present, for
backward compatibility.
- Works across all three configuration surfaces: Java DSL (model setter plus
a `namespacesRef`
method on the shared expression builder), XML DSL and YAML DSL - including
defining the
`Namespaces` bean itself declaratively (XML `<bean>` / YAML `beans:`),
using Camel's
`foo[bar]` map-syntax property binding against
`Namespaces.getNamespaces()`.
**Tests**: four, one per configuration surface plus a Saxon regression test.
`camel-core`, `camel-xml-io-dsl` and `camel-yaml-dsl` each cover a bean with
two namespace
prefixes, a positive match per namespace, a data-mismatch negative (correct
namespace, wrong
value) and a namespace-mismatch negative (correct value, wrong namespace
URI).
`camel-saxon` repeats this against a Saxon `XPathFactory`, and additionally
covers the
`resultType` path, to pin the compile-time resolution behaviour described
above.
**Documentation**: new sections in the XPath, XQuery and XML Tokenize
language pages showing the
bean definition and `namespacesRef` usage in XML and YAML, and noting that
inline namespaces
win. The XML Tokenize page had no namespaces section at all previously.
Supersedes #25561, which I closed myself pending the Saxon issue now fixed
here.
# Target
- [x] I checked that the commit is targeting the correct branch (Camel 4
uses the `main` branch)
# Tracking
- [x] If this is a large change, bug fix, or code improvement, I checked
there is a
[JIRA issue](https://issues.apache.org/jira/browse/CAM
(I didn't create a JIRA for this feature. It is something we needed in our
internal
project and decided it is general and useful enough to share)
# Apache Camel coding standards and style
- [x] I checked that each commit in the pull request hasd body.
- [x] I have run `mvn clean install -DskipTests` locally from root folder
and I have committed
all auto-generated changes.
# AI-assisted contributions
- [x] If this PR includes AI-generated code, commits havution
(e.g., `Co-authored-by` trailers) and the PR description identifies the AI
tool used.
_Written with Claude Code (Claude Opus 5) on behalf of @marcinwieckowski._
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