# INVALID_AGGREGATION_OP — unknown aggregation operator

Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. The supported operators are `sum`, `avg`, `min`, `max` and `stdev`, spelled lowercas…

<em>cyoda-go version <a href="https://github.com/Cyoda/cyoda-go/releases/tag/v0.8.4">0.8.4</a></em>

# errors.INVALID_AGGREGATION_OP

## NAME

INVALID_AGGREGATION_OP — an aggregation's `op` is not one of the supported operators.

## SYNOPSIS

HTTP: `400` `Bad Request`. Retryable: `no`.

## DESCRIPTION

Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. The supported operators are `sum`, `avg`, `min`, `max` and `stdev`, spelled lowercase. Anything else — including `count`, an uppercase spelling, or a typo — is rejected, and the message echoes the value that was sent.

There is no `count` operator because every bucket already carries `count`. `stdev` is the sample standard deviation (divisor `n − 1`) and is `null` when a bucket has fewer than two numeric samples.

## SEE ALSO

- errors
- crud
- errors.INVALID_AGGREGATION_FIELD
- errors.DUPLICATE_AGGREGATION_ALIAS

## See also

- [`cyoda help errors`](/help/errors/) — Every error response from the Cyoda REST API carries a structured `errorCode` in the `properties` object. Multiple codes may share the same HTTP status. Programmatic handling keys on `errorCode`, not HTTP status.
- [`cyoda help crud`](/help/crud/) — Entities are instances of models. Each entity has a UUID, a model reference (`entityName`, `modelVersion`), and a lifecycle state managed by the workflow engine. Creating an entity requires the referenced model to be in `LOCKED` state. All write operations run within a Cyoda transaction and return a `transactionId` alongside the affected entity IDs.
- [`cyoda help errors INVALID_AGGREGATION_FIELD`](/help/errors/invalid_aggregation_field/) — Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. An aggregation `field` obeys exactly the grammar a `groupBy` path does — a required `$.` leader followed by dot-separated segments of ASCII letters, digits, `_` and `-`, with no bracket-quoted access, array subscript or projection, recursive descent, whitespace or non-ASCII character. See `cyoda help errors INVALID_GROUP_BY_PATH` for the grammar and the rejected spellings; the message names the offending field and the reason.
- [`cyoda help errors DUPLICATE_AGGREGATION_ALIAS`](/help/errors/duplicate_aggregation_alias/) — Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. Each bucket's `aggregations` object is keyed by the aggregation's `as` alias, or — when `as` is omitted — by a synthesized `<op>_<field>` with the leading `$.` stripped, so `{"op":"sum","field":"$.amount"}` becomes `sum_amount`. Two aggregations that compute different things cannot share one key, because only one of the two values could be returned under it.

## Raw formats

- [`/help/errors/invalid_aggregation_op.json`](/help/errors/invalid_aggregation_op.json) — full descriptor (matches `GET /help/{topic}` envelope)
- [`/help/errors/invalid_aggregation_op.md`](/help/errors/invalid_aggregation_op.md) — body only