ContextQMD
Back to Strawberry

Relay wrong resolver annotation Error

docs/errors/relay-wrong-resolver-annotation.md

0.315.31.6 KB
Original Source

Relay wrong resolver annotation error

Description

This error is thrown when a field on a relay connection was defined with a resolver that returns something that is not compatible with pagination.

For example, the following code would throw this error:

python
from typing import Any

import strawberry
from strawberry import relay


@strawberry.type
class MyType(relay.Node): ...


@strawberry.type
class Query:
    @relay.connection(relay.Connection[MyType])
    def some_connection_returning_mytype(self) -> MyType: ...

    @relay.connection(relay.Connection[MyType])
    def some_connection_returning_any(self) -> Any: ...

This happens because the connection resolver needs to return something that can be paginated, usually an iterable/generator of the connection type itself.

How to fix this error

You can fix this error by annotating the resolver with one of the following supported types:

  • List[<NodeType>]
  • Iterator[<NodeType>]
  • Iterable[<NodeType>]
  • AsyncIterator[<NodeType>]
  • AsyncIterable[<NodeType>]
  • Generator[<NodeType>, Any, Any]
  • AsyncGenerator[<NodeType>, Any]

For example:

python
from typing import Any

import strawberry
from strawberry import relay


@strawberry.type
class MyType(relay.Node): ...


@strawberry.type
class Query:
    @relay.connection(relay.Connection[MyType])
    def some_connection(self) -> Iterable[MyType]: ...
<Note> Note that if you are returning a type different than the connection type, you will need to subclass the connection type and override its `resolve_node` method to convert it to the correct type, as explained in the [relay guide](../guides/relay). </Note>