hibernate/hibernate-orm · error · IllegalStateException

Not a compound selection

Error message

Not a compound selection

What it means

AbstractJpaSelection.getSelectionItems throws IllegalStateException when called on a selection that is not a compound selection. In the JPA Criteria API getSelectionItems() is only meaningful for selections built via multiselect()/tuple/array/construct builders that aggregate several items; the base implementation in Hibernate returns isCompoundSelection()==false and treats getSelectionItems() as an illegal call. Subclasses that are compound (e.g. SqmJpaCompoundSelection) override both methods.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/query/sqm/tree/spi/jpa/AbstractJpaSelection.java:43

	protected AbstractJpaSelection(@Nullable SqmBindableType<? super T> sqmExpressible, NodeBuilder criteriaBuilder) {
		super( sqmExpressible, criteriaBuilder );
	}

	@Nonnull
	@Override
	public JpaSelection<T> alias(@Nonnull String alias) {
		setAlias( alias );
		return this;
	}

	@Override
	public boolean isCompoundSelection() {
		return false;
	}

	@Override
	public List<? extends JpaSelection<?>> getSelectionItems() {
		throw new IllegalStateException( "Not a compound selection" );
	}
}

View on GitHub (pinned to fad1729dce)

Solutions

1. Guard with `if (selection.isCompoundSelection())` and treat non-compound as a single item
2. Use `List.of(selection)` for the non-compound branch so downstream code sees a uniform list
3. For explicit multi-item selections use cb.tuple()/cb.array()/cb.construct(...) or query.multiselect(...) so the compound implementation is used
4. In tree-walkers, recurse via instanceof checks on SqmExpression subtypes rather than assuming getSelectionItems exists

Example fix

// before
List<? extends JpaSelection<?>> items = query.getSelection().getSelectionItems(); // IllegalStateException for single select

// after
JpaSelection<?> sel = query.getSelection();
List<? extends JpaSelection<?>> items = sel.isCompoundSelection()
        ? sel.getSelectionItems()
        : List.of( sel );

if (selection.isCompoundSelection()) {
    items = selection.getSelectionItems();
} else {
    items = List.of(selection);
}

static List<? extends jakarta.persistence.criteria.Selection<?>> itemsOf(
        jakarta.persistence.criteria.Selection<?> s) {
    return s.isCompoundSelection() ? s.getSelectionItems() : List.of(s);
}

When it happens

Trigger: Calling `selection.getSelectionItems()` on a plain expression/path (a single SqmPath, literal, parameter, function result); generic result-mapping code that iterates `query.getSelection().getSelectionItems()` for both single and multi selects; transformers that flatten selection trees without checking isCompoundSelection first.

Common situations: DTO-projection frameworks that walk the criteria selection tree to derive column aliases/types; code that worked against multiselect queries breaking the first time it receives a single-item selection; migrating hand-rolled HQL result mapping to criteria where the selection is one expression.

Related errors

• JPA selection is not compound
• Blobs may not be accessed after serialization
• Clobs may not be accessed after serialization
• Unknown entity type '{}'
• Same column is added more than once with different values fo

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/7530c422f661c1ce. Report an issue: GitHub.