t8y2/dbx · error · java.lang.IllegalArgumentException

Index keys are required

Error message

Index keys are required

What it means

createIndex builds a MongoDB createIndexes command whose index specification needs a "key" document mapping fields to sort directions. After the keys_json parameter passes the requiredDocument check (present), the agent additionally rejects an empty keys document. An index with no keys is meaningless, so it throws IllegalArgumentException.

Solutions

1. Supply the index key fields, e.g. {"keys_json": {"field": 1}} or {"createdAt": -1}.
2. For compound indexes include every field, e.g. {"userId": 1, "createdAt": -1}.
3. If keys are computed at runtime, assert the resulting map is non-empty before calling createIndex.

Example fix

// before
{"database": "app", "collection": "orders", "keys_json": {}}
// after
{"database": "app", "collection": "orders", "keys_json": {"userId": 1, "createdAt": -1}}

if (!params.keys_json || Object.keys(params.keys_json).length === 0) {
  throw new Error("keys_json must contain at least one field, e.g. {field: 1}");
}

function hasIndexKeys(keys) {
  return keys != null && typeof keys === "object" && Object.keys(keys).length > 0;
}

try {
  await agent.createIndex({ database, collection, keys_json: keys, options_json: opts });
} catch (e) {
  if (String(e.message).includes("Index keys are required")) {
    console.error("Supply keys_json like {field: 1}");
  } else throw e;
}

When it happens

Trigger: Calling createIndex with {"keys_json": {}} — the parameter is present but contains no fields.

Common situations: Templates or generated calls leaving keys_json empty; a serialization bug producing an empty map; copying an example and deleting the keys to fill in later.

Understand the failure class

Background: Missing required parameter errors: what 'X is required' and 'the required X param is missing' mean, and how to fix them — this error's family across 27 libraries.

Related errors

• Index option "name" must be a non-empty string
• Index options cannot contain "key"; specify index fields in…
• runCommand requires a non-empty command document
• agentSessionId is required
• arrayFilters must be an array

AI-assisted analysis of t8y2/dbx@c0390bff16 (2026-09-05). Data as JSON: /api/errors/cb791432ed8c0961. Report an issue: GitHub.

Appendix: source

Thrown at agents/drivers/mongodb/src/main/java/com/dbx/agent/mongodb/MongoAgent.java:1003

    }

    private static boolean serverRequiresSerialDropIndexes(MongoClient client, String database) {
        try {
            Document buildInfo = client.getDatabase(database).runCommand(new Document("buildInfo", 1));
            return serverVersionRequiresSerialDropIndexes(serverVersionFromBuildInfo(buildInfo));
        } catch (RuntimeException error) {
            // Without an explicit old version, preserve MongoDB's single-command array semantics.
            return false;
        }
    }

    private static Object createIndex(JsonObject params) {
        MongoClient c = requireClient();
        String database = params.get("database").getAsString();
        String collection = params.get("collection").getAsString();
        Document keys = requiredDocument(params, "keys_json", "Index keys");
        if (keys.isEmpty()) {
            throw new IllegalArgumentException("Index keys are required");
        }

        Document index = new Document("key", keys);
        Document options = documentOrNull(params, "options_json");
        if (options != null) {
            if (options.containsKey("key")) {
                throw new IllegalArgumentException("Index options cannot contain \"key\"; specify index fields in keys JSON");
            }
            index.putAll(options);
        }
        String name;
        if (!index.containsKey("name")) {
            name = defaultIndexName(keys);
            index.put("name", name);
        } else if (!(index.get("name") instanceof String)) {
            throw new IllegalArgumentException("Index option \"name\" must be a non-empty string");
        } else {
            name = (String) index.get("name");

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