WIP defer support

[patrick91]

Worked on this with @bellini666

Still need to check:

• extensions
• commented out code
• stream (Streamable type)
• multipart subscriptions are probably broken

Summary by Sourcery

Implement support for @defer directive. This allows deferring the execution of specific fields in a query, improving initial response times.

New Features:

• Added support for the @defer directive, enabling deferred execution of selected fields within a query.

Tests:

• Added tests for the @defer directive, covering basic functionality and multipart subscriptions.

[sourcery-ai]

Reviewer's Guide by Sourcery

This PR implements support for @defer and @stream directives. It introduces handling for multipart responses in subscriptions and modifies the GraphiQL HTML to use a newer version.

Sequence diagram for incremental execution with @defer

sequenceDiagram
    participant Client
    participant Server
    participant GraphQL

    Client->>Server: Send GraphQL query with @defer
    Server->>GraphQL: Execute query incrementally
    GraphQL-->>Server: Return initial result
    Server-->>Client: Send initial response

    loop Subsequent Results
        GraphQL-->>Server: Return deferred result
        Server-->>Client: Send multipart response
    end

    Server-->>Client: Send end boundary

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Class diagram for incremental execution results

classDiagram
    class ExecutionResult
    class ExperimentalIncrementalExecutionResults
    class InitialIncrementalExecutionResult
    class SubsequentIncrementalExecutionResult
    class IncrementalResult
    class IncrementalDeferResult
    class IncrementalStreamResult

    ExperimentalIncrementalExecutionResults --> InitialIncrementalExecutionResult
    ExperimentalIncrementalExecutionResults --> SubsequentIncrementalExecutionResult

    IncrementalResult <|-- IncrementalDeferResult
    IncrementalResult <|-- IncrementalStreamResult

    class IncrementalDeferResult {
        +data
        +errors
        +path
        +label
        +extensions
    }

    class IncrementalStreamResult {
        +items
        +errors
        +path
        +label
        +extensions
    }

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Flow diagram for multipart response handling

flowchart TD
    A[Receive Query] --> B{Is Incremental?}
    B -->|Yes| C[Process Initial Result]
    C --> D[Send Initial Response]
    D --> E[Process Subsequent Results]
    E --> F{Has Next?}
    F -->|Yes| E
    F -->|No| G[Send End Boundary]

    B -->|No| H[Process Normal Result]
    H --> I[Send Response]

    style B decision
    style F decision

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File-Level Changes

Change	Details	Files
Implement @defer directive	Added handling for ExperimentalIncrementalExecutionResults in run method to support @defer. Modified execute to use experimental_execute_incrementally. Added process_incremental_result and process_subsequent_result methods to handle incremental results. Added tests for basic defer functionality. Updated process_result to handle InitialIncrementalExecutionResult objects.	strawberry/http/async_base_view.py strawberry/schema/execute.py tests/http/incremental/test_defer.py
Implement @stream directive	Added GraphQLStreamDirective to the schema. Updated release notes to mention @defer.	strawberry/schema/schema.py RELEASE.md
Update GraphiQL version	Updated GraphiQL library from version 3.0.9 to 3.8.3.	strawberry/static/graphiql.html
Implement multipart subscription support	Added encode_multipart_data method to format multipart responses. Added tests for multipart subscriptions. Added fixtures for testing multipart subscriptions. Removed old tests for multipart subscriptions.	strawberry/http/async_base_view.py tests/http/incremental/test_multipart_subscription.py tests/http/incremental/conftest.py tests/http/test_multipart_subscription.py
Update graphql-core dependency	Updated graphql-core dependency to version 3.3.0a6. Updated poetry.lock file to reflect the dependency change.	pyproject.toml poetry.lock

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[codspeed-hq]

CodSpeed Performance Report

Merging #3753 will improve performances by ×3.2

_{Comparing feature/defer-with-thiago (8c40f5a) with main (71f4c11)}

Summary

⚡ 3 improvements
✅ 18 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	feature/defer-with-thiago	Change
⚡	test_execute_generic_input	409.9 ms	366.1 ms	+11.95%
⚡	test_subscription_long_run[1000]	179 ms	59.3 ms	×3
⚡	test_subscription_long_run[20000]	3.5 s	1.1 s	×3.2

[codecov]

Codecov Report

Attention: Patch coverage is 7.81250% with 118 lines in your changes missing coverage. Please review.

Project coverage is 9.90%. Comparing base (fa5c2d0) to head (eb43d5e).
Report is 3 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (fa5c2d0) and HEAD (eb43d5e). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (fa5c2d0)	HEAD (eb43d5e)
	2	1

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #3753       +/-   ##
==========================================
- Coverage   97.27%   9.90%   -87.37%     
==========================================
  Files         504     502        -2     
  Lines       33481   32388     -1093     
  Branches     5503    1673     -3830     
==========================================
- Hits        32567    3208    -29359     
- Misses        703   29024    +28321     
+ Partials      211     156       -55     

[patrick91]

Me and Thiago spent a bit of time on this again today 😊 Here's a report of what we need to think about for next time:

handle_execution_results (or similar) is currently called from multiple places in execute (and subscribe). We were thinking of moving this to the schema class so that we reduce the places where this functions is called, but also we move this function call where the results are actually returned (in the http and ws integration).

We also need to think about the extensions field on the response, apparently this can be on the initial response, on the subsequent response and on each increment result.

Not sure how can fill it in the subsequent response data, see this test for the shape:

async def test_basic_defer(method: Literal["get", "post"], http_client: HttpClient):
    response = await http_client.query(
        method=method,
        query="""{
            hello

            ... @defer {
                asyncHello
            }
        }""",
    )

    async with contextlib.aclosing(response.streaming_json()) as stream:
        initial = await stream.__anext__()

        assert initial == {
            "data": {"hello": "Hello world"},
            "incremental": [],
            "hasNext": True,
            # TODO: why is this None?
            "extensions": None,
        }

        subsequent = await stream.__anext__()

        assert subsequent == {
            "incremental": [
                {
                    "data": {"asyncHello": "Hello world"},
                    "extensions": {"example": "example"},
                }
            ],
            "hasNext": False,
            # TODO: how do we fill these?
            "extensions": None,
        }