hibernate/hibernate-orm · error · IllegalStateException

Map instantiation contained one or more arguments with no al

Error message

Map instantiation contained one or more arguments with no alias

What it means

Thrown by DynamicInstantiationResultImpl.createResultAssembler when a `select new map(...)` query has at least one argument without an alias. This is the primary validation point and fires during query-plan creation (usually on first execution of the query). Because the alias becomes the map key, an unaliased argument makes the Map result impossible to construct.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/sql/results/graph/instantiation/internal/DynamicInstantiationResultImpl.java:137

	@SuppressWarnings("unchecked")
	private DomainResultAssembler<R> resolveAssembler(
			boolean areAllArgumentsAliased,
			boolean areAnyArgumentsAliased,
			List<String> duplicatedAliases,
			List<ArgumentReader<?>> argumentReaders,
			AssemblerCreationState creationState) {

		if ( nature == DynamicInstantiationNature.LIST ) {
			if ( LOG.isDebugEnabled() && areAnyArgumentsAliased ) {
				LOG.debug( "One or more arguments for List dynamic instantiation (`new list(...)`) specified an alias; ignoring" );
			}
			return (DomainResultAssembler<R>)
					new DynamicInstantiationAssemblerListImpl( (JavaType<List<?>>) javaType, argumentReaders );
		}
		else if ( nature == DynamicInstantiationNature.MAP ) {
			if ( ! areAllArgumentsAliased ) {
				throw new IllegalStateException( "Map instantiation contained one or more arguments with no alias" );
			}
			if ( !duplicatedAliases.isEmpty() ) {
				throw new IllegalStateException(
						"Map instantiation has arguments with duplicate aliases ["
								+ StringHelper.join( ",", duplicatedAliases ) + "]"
				);
			}
			return (DomainResultAssembler<R>)
					new DynamicInstantiationAssemblerMapImpl( (JavaType<Map<?,?>>) javaType, argumentReaders );
		}
		else {
			return assembler( areAllArgumentsAliased, duplicatedAliases, argumentReaders, creationState );
		}
	}

	private DomainResultAssembler<R> assembler(
			boolean areAllArgumentsAliased,
			List<String> duplicatedAliases,

View on GitHub (pinned to fad1729dce)

Solutions

Alias every argument in the map instantiation: `select new map(e.id as id, e.name as name)`
If a wrapper Map is genuinely wanted without keys, switch to `new list(...)` where aliases are optional
For Criteria API, set an alias on each Selection before adding it to the compound selection

Example fix

// before
List<Map<?,?>> rows = session.createQuery("select new map(e.id, e.name) from Employee e", Map.class).getResultList();
// after
List<Map<?,?>> rows = session.createQuery("select new map(e.id as id, e.name as name) from Employee e", Map.class).getResultList();

Defensive patterns

Strategy: validation

Validate before calling

// With Criteria API, fail fast before execution if any selection lacks an alias
List<Selection<?>> parts = cb.construct? null : null; // (illustrative)
for (Selection<?> s : compoundSelections) {
    if (s.getAlias() == null) throw new IllegalStateException("Selection needs alias for map instantiation: " + s);
}

Prevention

Alias all arguments when writing `new map(...)`; aliases are the map keys
Cover every HQL query with a test that executes it once so plan-time validation runs in CI
When migrating from `new list(...)` remember aliases go from optional to required

When it happens

Trigger: Executing `select new map(e.id, e.name) from Employee e` via `session.createQuery(...).getResultList()`; criteria query with DynamicInstantiationNature.MAP where selections lack aliases; first request after deployment triggers plan creation and fails.

Common situations: Developers writing `new map(...)` for the first time and not knowing aliases are mandatory; queries migrated from `new list(...)` or from native SQL; integration tests that only run the query late in the build, surfacing the failure at runtime instead of compile time.

Related errors

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/94e412b884ecdcfa. Report an issue: GitHub.