[WIP] Add websockets support to Sanic #3903

DoctorJohn · 2025-06-13T19:01:54Z

Description

TODO:

fix the test client
- The Sanic test client can only send requests to websocket endpoints, but cannot work with the actually websocket at all
- Sanic claims it can be run as an ASGI application, but doing that and using the resulting ASGI app with our ASGI test client doesn't work either: websocket route handlers suddenly receive an object that does not conform with a Sanic WebSocket at all, breaking everything
make the view easier to use: Sanic's HTTPMethodView cannot handle websockets. We could look at Blueprints or ask users to register route handlers individually.
resolve route conflicts: looks like Sanic does not allow GET and WebSocket route handlers on the same path (i.e., /graphql)

Types of Changes

Issues Fixed or Closed by This PR

Fixes Sanic - subscriptions not supported #2927

Summary by Sourcery

Add support for GraphQL subscriptions over WebSockets in Sanic by implementing a dedicated WebSocket adapter and extending the GraphQLView to handle WS connections, along with updated test client infrastructure.

New Features:

Introduce SanicWebSocketAdapter to enable GraphQL WebSocket transports.
Extend GraphQLView with a websocket() handler for subscription workflows and protocol negotiation.
Add keep-alive, debug, and protocol configuration options to GraphQLView initialization.
Integrate WebSocket routes into the Sanic test client and provide a ws_connect helper for testing.

Enhancements:

Unify HTTP and WebSocket request and context handling in GraphQLView methods.
Provide default implementations for subprotocol selection and WebSocket response creation.

Tests:

Update Sanic test client to register WebSocket routes and handle GraphQL WS transports.
Add an async ws_connect context manager for WebSocket integration tests.
Include SanicHttpClient in test suite configuration for WebSocket support.

the native sanic test client appears to be useless for testing websockets. they claim sanic apps can be run as asgi apps, but that changes the whole interface for websocket objects and breaks everything. nice

sourcery-ai · 2025-06-13T19:01:59Z

Reviewer's Guide

This PR adds full WebSocket support for Sanic by introducing a custom WebSocket adapter, extending the GraphQLView to handle WebSocket routes and protocols (including initialization parameters and runtime methods), enhancing the Sanic test client to exercise subscription endpoints, and updating the base view’s type signatures to accommodate WebSocket requests.

New Class Diagram: SanicWebSocketAdapter

classDiagram
    class AsyncWebSocketAdapter {
        %% Base class methods (conceptual)
    }
    class SanicWebSocketAdapter {
        +ws: Websocket
        +__init__(view: AsyncBaseHTTPView, request: Websocket, response: Websocket)
        +iter_json() AsyncGenerator~object, None~
        +send_json(message: Mapping~str, object~) None
        +close(code: int, reason: str) None
    }
    AsyncWebSocketAdapter <|-- SanicWebSocketAdapter

Updated Class Diagram: GraphQLView and AsyncBaseHTTPView WebSocket Handling

classDiagram
    class AsyncBaseHTTPView {
        +websocket_adapter_class: Callable[[Self, WebSocketRequest, WebSocketResponse], AsyncWebSocketAdapter] // Type hint 'Self' adopted
    }
    class GraphQLView {
        +keep_alive: bool  // New attribute
        +keep_alive_interval: float  // New attribute
        +debug: bool  // New attribute
        +protocols: Sequence[str]  // New attribute (from subscription_protocols)
        +connection_init_wait_timeout: timedelta  // New attribute
        +websocket_adapter_class: SanicWebSocketAdapter // Concrete adapter type assigned

        +get_root_value(request: Union[Request, Websocket]) Optional[RootValue] // Parameter type updated
        +get_context(request: Union[Request, Websocket], response: Union[TemporalResponse, Websocket]) Context // Parameter types updated
        +websocket(request: Request, ws: Websocket) Websocket // New method for WebSocket route
        +is_websocket_request(request: Union[Request, Websocket]) TypeGuard[Websocket] // Parameter type and return updated
        +pick_websocket_subprotocol(request: Websocket) Optional[str] // Parameter type updated
        +create_websocket_response(request: Websocket, subprotocol: Optional[str]) Websocket // Parameter type and return updated
    }
    AsyncBaseHTTPView <|-- GraphQLView

File-Level Changes

Change	Details	Files
Introduce SanicWebSocketAdapter and wire it into the GraphQLView	import GraphQL subscription protocol constants define SanicWebSocketAdapter with iter_json, send_json, close assign websocket_adapter_class in GraphQLView	`strawberry/sanic/views.py`
Extend GraphQLView to support WebSocket routes and options	add init parameters for keep_alive, protocols, debug, and timeouts implement async websocket(request, ws) entrypoint calling run() override is_websocket_request, pick_websocket_subprotocol, create_websocket_response adjust get_root_value and get_context to accept Websocket objects	`strawberry/sanic/views.py`
Enhance Sanic test client to drive WebSocket endpoints	extend test GraphQLView with WS mixin and handler classes use add_websocket_route instead of HTTP route registration add ws_connect contextmanager returning AsgiWebSocketClient	`tests/http/clients/sanic.py` `tests/websockets/conftest.py`
Adjust async_base_view typing for WebSocket adapters and multipart data	update websocket_adapter_class signature to use Self type change encode_multipart_data parameter type to object	`strawberry/http/async_base_view.py`

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#2927	Fix the reported error: `Cannot return null for non-nullable field Subscription.count.` when using subscriptions with Sanic.	✅
#2927	Enable subscriptions to work in Sanic web apps.	✅

Possibly linked issues

Sanic - subscriptions not supported #2927: The PR adds a Sanic websocket adapter and modifies the GraphQL view to enable websocket support for subscriptions.
Sanic - subscriptions not supported #2927: The PR adds websocket support to the Sanic integration, including the graphql-transport-ws and graphql-ws protocols mentioned in the issue.

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codecov · 2025-06-13T19:08:07Z

Codecov Report

Attention: Patch coverage is 75.36232% with 17 lines in your changes missing coverage. Please review.

Project coverage is 94.94%. Comparing base (758cd0b) to head (e85a1ba).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3903      +/-   ##
==========================================
- Coverage   95.06%   94.94%   -0.12%     
==========================================
  Files         515      515              
  Lines       33583    33634      +51     
  Branches     1736     1739       +3     
==========================================
+ Hits        31924    31934      +10     
- Misses       1377     1419      +42     
+ Partials      282      281       -1

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

codspeed-hq · 2025-06-13T19:14:45Z

CodSpeed Performance Report

Merging #3903 will not alter performance

_{Comparing DoctorJohn:add-websockets-support-to-sanic (e85a1ba) with main (758cd0b)}

Summary

✅ 21 untouched benchmarks

WIP test client does not work

e85a1ba

the native sanic test client appears to be useless for testing websockets. they claim sanic apps can be run as asgi apps, but that changes the whole interface for websocket objects and breaks everything. nice

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Description

Types of Changes

Issues Fixed or Closed by This PR

Summary by Sourcery

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Reviewer's Guide

New Class Diagram: SanicWebSocketAdapter

Updated Class Diagram: GraphQLView and AsyncBaseHTTPView WebSocket Handling

File-Level Changes

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Possibly linked issues

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