hibernate/hibernate-orm · error · ConversionException

Could not determine ValueMapping for SqmExpression: {}

Error message

Could not determine ValueMapping for SqmExpression: {}

What it means

determineValueMapping could not resolve a MappingModelExpressible for an SqmExpression: it found no value mapping for the expression itself and no inferred type on the inferrable-type stack. Literals are explicitly tolerated (null is returned), but every other unmappable expression aborts translation with a ConversionException echoing the expression.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/query/sqm/sql/spi/BaseSqmToSqlAstConverter.java:6524

		}


		final var valueMapping =
				domainModel.resolveMappingExpressible( nodeType, fromClauseIndex::getTableGroup );

		if ( valueMapping == null ) {
			final var mappingModelExpressible = resolveInferredType();
			if ( mappingModelExpressible != null ) {
				return mappingModelExpressible;
			}
		}

		if ( valueMapping == null ) {
			// For literals, it is totally possible that we can't figure out a mapping type
			if ( sqmExpression instanceof SqmLiteral<?> ) {
				return null;
			}
			throw new ConversionException( "Could not determine ValueMapping for SqmExpression: " + sqmExpression );
		}

		return valueMapping;
	}

	protected MappingModelExpressible<?> getInferredValueMapping() {
		final var inferredMapping = resolveInferredType();
		if ( inferredMapping != null ) {
			if ( inferredMapping instanceof PluralAttributeMapping pluralAttributeMapping ) {
				return pluralAttributeMapping.getElementDescriptor();
			}
			if ( inferredMapping instanceof TupleMappingModelExpressible tuple ) {
				final var elementExpressible =
						tuple.findComponentMappingModelExpressible( CollectionPart.Nature.ELEMENT.getName() );
				return elementExpressible == null ? inferredMapping : elementExpressible;
			}
			else if ( !( inferredMapping instanceof JavaObjectType ) ) {
				// Never report back the "object type" as inferred type and instead rely on the value type

View on GitHub (pinned to fad1729dce)

Solutions

  1. Give the expression a type to infer from: 'cast(null as Integer)', 'coalesce(x, 0)' with typed branches
  2. Use typed parameters (cb.parameter(Integer.class)) instead of raw Object ones
  3. Reference a mapped path on one side of the expression so the other side can be inferred
  4. Simplify the expression tree - split compound arithmetic into steps Hibernate can type

Example fix

// before
select o.id, null from Ord o order by 2

// after
select o.id, cast(null as Integer) from Ord o
Defensive patterns

Strategy: try-catch

Validate before calling

// For dynamic criteria projections: reject expressions without a resolvable Java type
Expression<?> sel = ...;
if (sel.getJavaType() == Object.class || sel.getJavaType() == null) {
    throw new IllegalArgumentException("Projection lacks a concrete type; wrap with cb.cast(...));");
}

Try / catch

try {
    return session.createQuery(cq).getResultList();
} catch (org.hibernate.query.sqm.tree.SqmConversionException | RuntimeException e) {
    // ConversionException extends HibernateException; detect by class name to stay import-safe
    if (e.getClass().getSimpleName().equals("ConversionException")) {
        log.error("Unresolvable expression type in criteria query", e);
    }
    throw e;
}

Prevention

When it happens

Trigger: An untyped 'null' in the select list or order-by with nothing to infer the type from; criteria expressions typed Object; arithmetic over expressions whose operand types cannot be resolved (e.g. parameters of unknown type on both sides); comparing a subquery result that itself has no mapping.

Common situations: Dynamic criteria queries building projections from loosely typed expressions; HQL with coalesce/cast of null without a typed second branch; mixing parameters of raw types in predicates; queries that worked on older 6.x and break after inference changes.

Related errors

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/70629da7d4c83fcb. Report an issue: GitHub.