What causes "Cannot coerce value '%s' [%s] to Float" in hibernate/hibernate-orm?

Convert to Float yourself before binding: Float.parseFloat on a normalized string or ((Number) v).floatValue()

hibernate/hibernate-orm · error · CoercionException

Cannot coerce value '%s' [%s] to Float

Error message

Cannot coerce value '%s' [%s] to Float

What it means

FloatJavaType.coerce(Object) is the last-chance conversion of an arbitrary value to Float for float-typed attributes and parameters: it delegates to coerceOrNull and throws CoercionException('Cannot coerce value ... to Float'), naming the value and its class, when no coercion rule matched.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/type/descriptor/java/FloatJavaType.java:173

	@Override
	public int getDefaultSqlPrecision(Dialect dialect, JdbcType jdbcType) {
		return jdbcType.isFloat()
				// this is usually the number of *binary* digits
				// in a single-precision FP number
				? dialect.getFloatPrecision()
				// this is the number of decimal digits in a Java float
				: 8;
	}

	@Override
	public @Nullable Float coerce(@Nullable Object value) {
		if ( value == null ) {
			return null;
		}
		final var coerced = coerceOrNull( value );
		if ( coerced == null ) {
			throw new CoercionException(
					String.format(
							Locale.ROOT,
							"Cannot coerce value '%s' [%s] to Float",
							value,
							value.getClass().getName()
					)
			);
		}
		return coerced;
	}

	@Override
	public @Nullable Float coerceOrNull(@Nonnull Object value) {
		if ( value instanceof Float floatValue ) {
			return floatValue;
		}

		if ( value instanceof Number number ) {

View on GitHub (pinned to fad1729dce)

Solutions

Convert to Float yourself before binding: Float.parseFloat on a normalized string or ((Number) v).floatValue()
Fix the producer of the value (correct Locale, trimmed input)
Type the query parameter explicitly so coercion is not guessed
Catch CoercionException at the boundary and map it to a validation error

Example fix

// before
q.setParameter("ratio", userInput); // String "abc" -> CoercionException

// after
q.setParameter("ratio", Float.parseFloat(userInput.trim()));

Defensive patterns

Strategy: type-guard

Validate before calling

static Float toFloatOrNull(Object v) {
    try {
        return v instanceof Number n ? n.floatValue()
                : Float.parseFloat(String.valueOf(v).trim());
    } catch (RuntimeException e) {
        return null;
    }
}

Type guard

static boolean coercibleToFloat(Object v) {
    if (v == null || v instanceof Number || v instanceof Boolean) return true;
    return v instanceof String s && s.trim().matches("[+-]?([0-9]+(\\.[0-9]*)?|\\.[0-9]+)([eE][+-]?[0-9]+)?");
}

Try / catch

try {
    return q.setParameter("ratio", value).getSingleResult();
} catch (CoercionException e) {
    throw new BadRequestException("ratio must be numeric", e);
}

Prevention

Convert external input to Float before binding
Normalize decimal separators and trim whitespace at the edge
Type parameters explicitly instead of relying on coercion

When it happens

Trigger: Binding a query parameter or setting a float-typed attribute with an unconvertible value: non-numeric or locale-formatted strings, arbitrary object types (Date, POJO, char[]) that the coercion helper does not recognize.

Common situations: setParameter with user input parsed as the wrong type; JSON/deserializer output mapped directly onto float fields; consuming loosely typed maps.

Related errors

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/12eed653ca357453. Report an issue: GitHub.