hibernate/hibernate-orm · error · UnsupportedOperationException

Function roots can not be treated

Error message

Function roots can not be treated

What it means

TREAT is defined for entity inheritance hierarchies; a SqmFunctionRoot (a root derived from a function call) does not participate in one, so treatAs throws UnsupportedOperationException. Filter predicates on the function result's columns are the supported alternative to downcasting.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/query/sqm/tree/spi/domain/SqmFunctionRoot.java:121

	public String getEntityName() {
		throw new UnsupportedOperationException( "Function root does not have an entity type. Use getReferencedPathSource() instead." );
	}

	@Override
	public SqmPathSource<E> getResolvedModel() {
		return getReferencedPathSource();
	}

	@Override
	@Nonnull
	public SqmCorrelatedRoot<E> createCorrelation() {
		throw new UnsupportedOperationException();
	}

	@Override
	@Nonnull
	public <S extends E> SqmTreatedFrom<E, E, S>  treatAs(@Nonnull EntityDomainType<S> treatTarget, @Nullable String alias, boolean fetch) {
		throw new UnsupportedOperationException( "Function roots can not be treated" );
	}

	@Override
	public boolean deepEquals(SqmFrom<?, ?> object) {
		return super.deepEquals( object )
			&& function.equals( ((SqmFunctionRoot<?>) object).function );
	}

	@Override
	public boolean isDeepCompatible(SqmFrom<?, ?> object) {
		return super.isDeepCompatible( object )
			&& function.isCompatible( ((SqmFunctionRoot<?>) object).function );
	}
}

View on GitHub (pinned to fad1729dce)

Solutions

1. Replace TREAT with WHERE conditions on the function result's type/kind attribute (e.g. where g.kind = 'SUB')
2. Move the polymorphic part to a real entity association elsewhere in the query and TREAT that instead
3. Restructure so the function returns a single concrete type and do subtype filtering in SQL or Java

Example fix

// before
from json_rows(p.doc) g join treat(g as SpecialRow) s -- treat on function root

// after
from json_rows(p.doc) g where g.kind = 'SPECIAL'
-- filter on the type/kind column; or join a real entity association and TREAT that

static boolean treatableRoot(SqmRoot<?> root) {
    return !(root instanceof SqmFunctionRoot<?>);
}

try {
    SqmTreatedFrom<?, ?, ?> t = root.treatAs(target, alias, false);
} catch (UnsupportedOperationException e) {
    // function roots are never treatable: replace with a WHERE type/kind predicate
    throw new IllegalStateException("Use a filter predicate instead of TREAT on function roots", e);
}

When it happens

Trigger: HQL 'treat(f(x) as Sub)' in the FROM clause, or criteria calling functionRoot.treatAs(SubType.class, alias, false) on a function-derived root.

Common situations: Applying boilerplate TREAT patterns to new function-root queries; set-returning functions that conceptually return different row kinds; porting SQL's joins over type-discriminated subqueries into HQL.

Related errors

• Cannot apply TREAT operator to discriminator path
• Non-aggregate composite paths cannot be TREAT-ed
• Basic-value cannot be treated (downcast)
• Derived roots can not be treated
• Embeddable paths cannot be TREAT-ed to an entity type

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/ce689c9b448da62f. Report an issue: GitHub.