[borinquenkid]

Fixes #16809

Stacked on #16823 (chain: #16816, #16817, #16818, #16820, #16821, #16822, #16823). no ci until the chain reaches 8.0.x.

Problem

Person.where { age > avg(age) } and the other aggregate subqueries documented for where put a DetachedCriteria in the comparison. SQL datastores run it as a subquery. MongoDB and Neo4j compared the property with the criteria object and returned no rows, without an error (the issue reports a MissingMethodException for some forms). inList / notIn against a subquery, exists and the all / some forms had the same gap.

Changes

• Query.resolveSubqueries(Junction) (new, protected, @since 8.0.1) runs each subquery and returns a copy of the criteria that holds the results. The criteria passed in are not changed, so a reused where query runs its subqueries again each time.
  • ==, !=, >, >=, <, <= take the one value the subquery returns (an empty result compares with null);
  • inList takes every row, and notIn becomes a negated inList;
  • a comparison against a subquery that returns more than one row, exists, notExists and the all / some forms throw InvalidDataAccessResourceUsageException naming the form or the property.
• MongoQuery.executeQuery and Neo4jQuery.executeQuery call it first.
• Docs: where reference and upgrade guide section 26.16.

Two queries instead of one $expr pipeline or a Cypher subquery: the result is a snapshot taken when the query runs, which is what a where query already is on the SQL datastores' first read. A native $expr / CALL translation can replace the substitution later without changing behavior.

Tests

• AggregateSubquerySpec for MongoDB (12) and Neo4j (9): avg with >, >=, <, <=, the .of { } closure, max, min, sum, ==, !=, negation, ||, inList, notIn, the multi-row and exists errors, and a repeat run that sees new data. All fail without the change (10 of 10 and 7 of 7 when I checked before adding the later cases).
• Full suites: grails-data-mongodb-core 1036 tests and grails-data-neo4j-core 623, 0 failures; grails-datastore-core 348, 0 failures. codeStyle, validateRepositoryConventions and rat pass.
• PITest (feat(build-logic): add opt-in PITest mutation testing support and skill #16819, cross-module): 43 mutants in the new Query code, 43 killed.

Not in this PR

• A native $expr / Cypher translation (see above).
• count as an aggregate comparison is untested here and not documented.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has insufficient remaining quota. Try requesting a review at a lower effort level.

[borinquenkid]

Replaced by #16875, which has only this change on 8.0.x. This branch sat on top of the chain #16816 to #16823, so its diff against 8.0.x was the whole chain. Closing; the review history here was Copilot's only.