strawberry-django-aggregates

Hasura-shape aggregations over Django querysets in Strawberry GraphQL.

count · count_distinct · sum · avg · min · max · stddev · variance · bool_and · bool_or · array_agg · string_agg — composed with multi-level group_by, having filters, and ordering on aggregate aliases. Inspired by Hasura's <table>_aggregate, PostGraphile's pg-aggregates, and Odoo 18's _read_group. Built for strawberry-django over PostgreSQL and SQLite.

from decimal import Decimal
from datetime import datetime
from strawberry import auto
import strawberry, strawberry_django
from strawberry_django_aggregates import AggregateBuilder

from .models import Order

@strawberry_django.type(Order)
class OrderType:
    id: auto
    customer: "CustomerType"
    total: Decimal
    status: str
    created_at: datetime

# One call wires count/sum/avg/min/max + group_by + having into the schema:
order_aggs = AggregateBuilder(
    model=Order,
    aggregate_fields=["total"],
    group_by_fields=["customer", "status", "created_at"],
).build()

@strawberry.type
class Query:
    orders_aggregate = order_aggs.aggregate_field
    orders_group_by  = order_aggs.group_by_field

Generates a fully-typed GraphQL surface:

type Query {
  ordersAggregate(filter: OrderFilter): OrderAggregate!
  ordersGroupBy(
    filter:    OrderFilter
    groupBy:   [OrderGroupBySpec!]!
    having:    OrderHaving
    orderBy:   [OrderGroupOrder!]
    pagination: OffsetPagination
  ): OrderGroupedResult!
}

type OrderAggregate {
  count:           Int!
  countDistinct(field: OrderCountableField!): Int!
  sum:             OrderSumFields
  avg:             OrderAvgFields
  min:             OrderMinFields
  max:             OrderMaxFields
  stddev:          OrderStddevFields    # Postgres only
  variance:        OrderVarianceFields  # Postgres only
}

type OrderGrouped {
  key:   OrderGroupKey!   # composite — every requested groupBy field present
  count: Int!
  sum:   OrderSumFields
  # ... no recursive subgroups field — flat results
}

Features

• Hasura-canonical schema shape. <Model>Aggregate { count, countDistinct, sum, avg, min, max, stddev, variance, boolAnd, boolOr, arrayAgg, stringAgg }.
• Odoo-grade group-by. Multi-level via composite keys (flat result rows), dual date-granularity tracks (date_trunc returning DateTime AND date_part::int returning Int), timezone-correct bucketing.
• HAVING with aggregate aliases. { countGt: 5, sumTotalGt: 1000 } — typed inputs generated per measure.
• Ordering on aggregates. [{ field: "total:sum", direction: DESC }] — fail-loud on unknown terms (Odoo's pre-17 silent-drop bug avoided).
• Standalone backend primitive. compute_aggregation(qs, group_by, aggregates, having, order_by, ...) is callable from any Python context — DRF view, Celery task, admin script, MCP tool — not just GraphQL resolvers.
• Exact group cardinality. AggregateBuilder.count_groups(...) returns the database-side group count before pagination for custom grouped envelopes, including filters, granularity, JSON paths, and HAVING.
• Determinism. Type generation produces byte-identical SDL for the same inputs.
• No magic. Every operator, every granularity, every type is whitelisted.

Non-goals

• Cross-database aggregation. PostgreSQL + SQLite only. SQLite degrades gracefully on array_agg/string_agg/stddev/variance — those operators raise OperatorNotSupportedError at resolver entry.
• Auto-traversal of one-to-many / many-to-many for measures. This is the silent row-multiplication footgun Odoo refuses to ship; we follow. array_agg is the explicit escape hatch.
• Permission integration. The library expects a pre-scoped queryset — the caller has already applied accessible_by(user) or equivalent. This keeps the library compatible with django-guardian, django-rules, django-rebac (when shipped), or hand-rolled permission systems.

Status

Beta (v0.10.0). The schema shape, operator vocabulary, and compute_aggregation signature are stable for early adopters, but minor-level iteration is still expected before a 1.0 stability commitment — see docs/SPEC.md § 16. Runtime: Python 3.14, Django 6.0.

Documentation

• Full contract: docs/SPEC.md — operator catalog, granularity tracks, HAVING semantics, ordering rules, timezone handling, and the Odoo-derived footgun audit.
• Naming and wire vocabulary: docs/TERMINOLOGY.md
• Contributor quality gate: CONTRIBUTING.md

License

BSD-3-Clause.