How do I write a Jahia rule that runs when a node is published?

Question

How do I write a Jahia rule that runs when a node is published?

Answer

Use the DSL sentence A node is published, together with a condition on the node type or a property:

rule "React to publication"
    when
        A node is published
            - the node has the type mynt:myType
    then
>       logger.info("published {}", node.getPath());
end

Jahia ships four publication sentences, all backed by the same PublishedNodeFact:

Publish and unpublish are the same fact type, separated by a flag, so a pattern that does not constrain it will match both.

A publication emits more than one fact

This is the part that surprises people. Publishing a node that has internationalized properties emits a fact for the node and a separate fact per translated language.

Measured on Jahia 8.2.3.2, publishing one node with an English title:

The raw pattern fires twice because it matches the node fact and the translation fact. That is exactly what the DSL sentences protect you from - each one pins translation to true or false. If your rule is running twice per publication, this is almost certainly why.

On the translation fact, getPath() returns the parent node's path, not the j:translation_xx child, and getLanguage() gives you the locale.

It runs in more than one workspace

The same rule file is loaded by several listeners. In the same measurement, one publication fired the rule once with workspace=default and once with workspace=live.

So a rule in rules.drl reacting to publication runs twice, once per listener. If you only want one execution, guard on the workspace global, which is available in the consequence.

"Unable to expand" when you write the pattern by hand

A file that declares expander rules.dsl expects every line in when to be a DSL sentence. A raw Drools pattern must be prefixed with >, or compilation fails:

rule "broken"
    when
        $published : PublishedNodeFact( unpublished == false )
    then
        ...
end

Errors when compiling rules in file [...] : [9] Unable to expand:
$published : PublishedNodeFact( unpublished == false )

The fix is the > prefix:

rule "works"
    when
>       $published : PublishedNodeFact( unpublished == false )
    then
>       logger.info("published {}", $published.getPath());
end

Both forms above were compiled on 8.2.3.2: the first produced that exact error, the second loaded and fired.

Remember that a hand-written pattern loses the translation == false constraint the DSL sentence would have given you - which is the double-firing described earlier.

This article was drafted with AI assistance, then reviewed and curated by Jahia Customer Support engineers before publication.