shashank created CAMEL-25455:
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Summary: camel-wasm - the wasm predicate never matches a Boolean,
String or byte[] result
Key: CAMEL-25455
URL: https://issues.apache.org/jira/browse/CAMEL-25455
Project: Camel
Issue Type: Bug
Reporter: shashank
{{WasmExpression.matches()}} (camel-wasm, main e1bdb2f124b4, line 142) only
returns true for a Jackson {{BooleanNode}} or a non-empty
{{java.util.Collection}}; every other result is false. The result type of the
{{wasm}} language defaults to {{byte[]}} (the raw bytes the function returns),
so as a predicate it never matches:
{code:java}
from("direct:in")
.filter().wasm("is_valid", "classpath:functions.wasm") // byte[] result:
never passes
.to("direct:valid");
{code}
With {{resultType}} {{Boolean}} the expression evaluates to {{Boolean.TRUE}}
and {{matches()}} still returns false; the same with {{String}}. A predicate
only works with {{resultType=com.fasterxml.jackson.databind.JsonNode}} plus a
Jackson type converter on the classpath (camel-jackson is not a dependency of
camel-wasm), which is not documented. The checks date from the original
contribution (CAMEL-20336) and match camel-jq, whose result is always a
{{JsonNode}}.
h3. Reproduction
{{filter().wasm("transform", "functions.wasm", resultType)}} with the
{{functions.wasm}} module of the camel-wasm tests ({{transform}} upper-cases
the body) and bodies {{false}}, empty and {{true}}: on main no message passes
for {{byte[]}}, {{String}} or {{Boolean}} ({{mock://result Received message
count. Expected: <1> but was: <0>}}, two runs). A survey probe with a guest
that returns {{true}}: {{evaluate}} -> {{true}} ({{java.lang.Boolean}}),
{{matches}} -> {{false}}; the Filter EIP passed 0 of 1.
h3. Proposed fix
Evaluate the result with {{ObjectHelper.evaluateValuePredicate}} like
{{ExpressionSupport}}, camel-bean and camel-quickjs ({{Boolean}} as is,
{{true}}/{{false}} text in any case, empty is false, other non-null values
true), converting a {{byte[]}} result to a {{String}} with the exchange charset
first. Keep the JSON case as it is: a {{JsonNode}} only matches when it is the
boolean {{true}}. Docs: a predicate section in the language page; a short
upgrade-guide note since predicates that never matched can now match.
Affected: since 4.5 (the wasm language), main included.
Duplicate check (2026-10-07): no camel-wasm JIRA component; text search "wasm"
finds CAMEL-20336, CAMEL-21569, CAMEL-24059 (all resolved, none about
predicates). GitHub pull requests "wasm": none open on this.
_Filed with Claude Code on behalf of allthingssecurity._
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