spring-projects/spring-ai · error · RuntimeException

Not supported expression type:

Error message

Not supported expression type:

What it means

MongoDBAtlasFilterExpressionConverter.getOperationSymbol maps Spring AI Filter.Op values to MongoDB Atlas comparison operators ($lt, $gt, $in, etc.) and throws a RuntimeException("Not supported expression type:") in the default branch when it encounters an operator it cannot translate to an Atlas Search filter clause.

Source

Thrown at vector-stores/spring-ai-mongodb-atlas-store/src/main/java/org/springframework/ai/vectorstore/mongodb/atlas/MongoDBAtlasFilterExpressionConverter.java:81

		context.append(getOperationSymbol(expression));
		context.append(":");
		this.convertOperand(expression.right(), context);
		context.append("}}");
	}

	private String getOperationSymbol(Filter.Expression exp) {
		return switch (exp.type()) {
			case AND -> "$and";
			case OR -> "$or";
			case EQ -> "$eq";
			case NE -> "$ne";
			case LT -> "$lt";
			case LTE -> "$lte";
			case GT -> "$gt";
			case GTE -> "$gte";
			case IN -> "$in";
			case NIN -> "$nin";
			default -> throw new RuntimeException("Not supported expression type:" + exp.type());
		};
	}

	@Override
	protected void doKey(Filter.Key filterKey, StringBuilder context) {
		var identifier = filterKey.key();
		emitJsonValue("metadata." + identifier, context);
	}

	/**
	 * Serialize values using JSON serialization for MongoDB Atlas filter expressions.
	 * Delegates to {@link #emitJsonValue(Object, StringBuilder)} for Jackson-based JSON
	 * serialization.
	 * @param value the value to serialize
	 * @param context the context to append the JSON representation to
	 */
	@Override
	protected void doSingleValue(Object value, StringBuilder context) {

View on GitHub (pinned to 98a7beda4f)

Solutions

1. Rewrite the filter using only supported operators: EQ, NE, GT, GTE, LT, LTE, IN, NIN.
2. Replace LIKE/CONTAINS expressions with EQ against an exact value or precompute the match in metadata.
3. Upgrade spring-ai-mongodb-atlas-store to the latest version for broader operator support.
4. Implement a custom FilterExpressionConverter extending the Atlas converter to handle the missing op.
5. Split complex filters into supported compound expressions (AND/OR of supported ops).

Example fix

// before
new FilterExpressionBuilder().like("genre", "doc").build();
// after
new FilterExpressionBuilder().eq("genre", "documentary").build(); // use supported EQ instead of LIKE

// validate filter ops before passing to Atlas search
static boolean isSupportedOp(Filter.Expression exp) {
    return switch (exp.type()) {
        case EQ, NE, GT, GTE, LT, LTE, IN, NIN, AND, OR -> true;
        default -> false; // LIKE, CONTAINS etc. will throw in the Atlas converter
    };
}

boolean isSupportedFilter(Expression filter) {
    if (filter instanceof Filter.Expression exp) {
        return isSupportedOp(exp);
    }
    return filter instanceof Filter.Group g && g.expressions().stream().allMatch(MyGuards::isSupportedFilter);
}

try {
    vectorStore.similaritySearch(SearchRequest.builder().query(q).filterExpression(expr).build());
} catch (RuntimeException e) {
    if (e.getMessage().startsWith("Not supported expression type")) {
        throw new IllegalArgumentException("Rewrite filter with supported ops: EQ/NE/GT/GTE/LT/LTE/IN/NIN", e);
    }
    throw e;
}

When it happens

Trigger: Passing a Filter.Expression whose Op is not EQ/NE/GT/GTE/LT/LTE/IN/NIN (e.g. LIKE, CONTAINS, or nested unsupported combinators) into a SearchRequest filter expression used with MongoDBAtlasVectorStore.

Common situations: Building a filter with string matching ops (LIKE/CONTAINS) which Atlas vector search filters do not support this way; using a newer Filter.Op added to Spring AI but not handled by this converter version; version drift between spring-ai-core and the Atlas store module.

Related errors

• Failed to delete documents by filter
• Not supported expression type:
• Unsupported operator:
• Unsupported operand type:
• Expression of type %s requires a left operand

AI-assisted analysis of spring-projects/spring-ai@98a7beda4f (2026-09-11). Data as JSON: /api/errors/f698c476b67bf720. Report an issue: GitHub.