# MISSING_GROUP_BY — grouped-stats request supplied no groupBy dimension

Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. `groupBy` is required and must carry at least one dimension: the endpoint returns on…

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

# errors.MISSING_GROUP_BY

## NAME

MISSING_GROUP_BY — the grouped-statistics request omitted `groupBy`, or sent it as an empty array.

## SYNOPSIS

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

## DESCRIPTION

Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. `groupBy` is required and must carry at least one dimension: the endpoint returns one bucket per distinct group key, and there is no reading of the request that groups by nothing.

Supply at least one entry — either the reserved token `state` (lifecycle state) or a scalar JSONPath into the payload, such as `$.country`. For an ungrouped count of a model's entities, use the model statistics endpoint instead.

## SEE ALSO

- errors
- crud
- errors.DUPLICATE_GROUP_BY
- errors.INVALID_GROUP_BY_PATH

## 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 DUPLICATE_GROUP_BY`](/help/errors/duplicate_group_by/) — Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. The reserved token `state` appearing twice, or the same JSONPath appearing twice, is rejected rather than deduplicated: a repeated dimension adds a second copy of the same value to every bucket's `groupKey` and changes nothing about the grouping, so it is more likely a mistake in the request than an intent.
- [`cyoda help errors INVALID_GROUP_BY_PATH`](/help/errors/invalid_group_by_path/) — Raised by `POST /api/entity/stats/{entityName}/{modelVersion}/query`. Every `groupBy` entry other than `state` must match the wire JSONPath grammar — a required `$.` leader followed by dot-separated segments of ASCII letters, digits, `_` and `-`:

## Raw formats

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