# DUPLICATE_AGGREGATION_ALIAS — two aggregations claim the same response key

Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. Each buckets `aggregations` object is keyed by the aggregations `as` alias, or — w…

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

# errors.DUPLICATE_AGGREGATION_ALIAS

## NAME

DUPLICATE_AGGREGATION_ALIAS — two aggregations over different `(op, field)` pairs resolve to the same key in the response.

## SYNOPSIS

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

## DESCRIPTION

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.

The collision can arise between two explicit aliases, or between an explicit alias and a synthesized one (`as: "sum_amount"` on one entry alongside an unaliased `sum` over `$.amount` on another). The message carries the contested alias.

Repeating the *same* `(op, field)` pair does not raise this — identical pairs are deduplicated silently, since both would compute the same value.

Give the colliding aggregations distinct `as` aliases.

## SEE ALSO

- errors
- crud
- errors.INVALID_AGGREGATION_OP
- errors.INVALID_AGGREGATION_FIELD

## 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_OP`](/help/errors/invalid_aggregation_op/) — 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.
- [`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.

## Raw formats

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