resolvers.md

title
Resolvers

Custom Resolvers

Basic resolvers are generated automatically once the types are declared.

However it is possible to override them with custom resolvers.

Sync resolvers

Sync resolvers can be used in both ASGI/WSGI and will be automatically wrapped in sync_to_async when running async.

import strawberry_django
from strawberry import auto
from . import models

@strawberry_django.type(models.Color)
class Color:
    id: auto
    name: auto

    @strawberry_django.field
    def fruits(self) -> list[Fruit]:
        return self.fruits.objects.filter(...)

Async resolvers

Async resolvers can be used when running using ASGI.

import strawberry_django
from strawberry import auto
from . import models
from asgiref.sync import sync_to_async

@strawberry_django.type(models.Color)
class Color:
    id: auto
    name: auto

    @strawberry_django.field
    async def fruits(self) -> list[Fruit]:
        return sync_to_async(list)(self.fruits.objects.filter(...))

Optimizing resolvers

When using custom resolvers together with the Query Optimizer Extension you might need to give it a "hint" on how to optimize that field

Take a look at the optimization hints docs for more information about this topic.

Issues with Resolvers

It is important to note that overriding resolvers also removes default capabilities (e.g. Pagination, Filter), exception for relay connections. You can however still add those by hand and resolve them:

import strawberry
from strawberry import auto
from strawberry.types import Info
import strawberry_django
from . import models


@strawberry_django.filter(models.Fruit, lookups=True)
class FruitFilter:
    id: auto
    name: auto


@strawberry_django.type(models.Fruit, order=FruitOrder)
class Fruit:
    id: auto
    name: auto


@strawberry_django.type(models.Fruit, is_interface=True)
class Fruit:
    id: auto
    name: auto


@strawberry.type
class Query:
    @strawberry_django.field
    def fruits(
        self,
        filters: FruitFilter | None = strawberry.UNSET,
        order: FruitOrder | None = strawberry.UNSET,
        info: Info
    ) -> list[Fruit]
        qs = models.fruit.objects.all()

        # apply filters if defined
        if filters is not strawberry.UNSET:
            qs = strawberry_django.filters.apply(filters, qs, info)

        # apply ordering if defined
        if order is not strawberry.UNSET:
            qs = strawberry_django.ordering.apply(filters, qs)

        return qs