🐛 Fix response model serialization options for SSE event data

fastapi/routing.py

@@ -507,7 +507,14 @@ def get_request_handler(
                             data_str: str | None = item.raw_data
                         elif item.data is not None:
                             if hasattr(item.data, "model_dump_json"):
-                                data_str = item.data.model_dump_json()
+                                data_str = item.data.model_dump_json(
+                                    include=response_model_include,
+                                    exclude=response_model_exclude,
+                                    by_alias=response_model_by_alias,
+                                    exclude_unset=response_model_exclude_unset,
+                                    exclude_defaults=response_model_exclude_defaults,
+                                    exclude_none=response_model_exclude_none,
+                                )
                             else:
                                 data_str = json.dumps(jsonable_encoder(item.data))
                         else:

tests/test_sse.py

@@ -8,7 +8,7 @@ from fastapi import APIRouter, FastAPI
 from fastapi.responses import EventSourceResponse
 from fastapi.sse import ServerSentEvent
 from fastapi.testclient import TestClient
-from pydantic import BaseModel
+from pydantic import BaseModel, Field
 
 
 class Item(BaseModel):
@@ -16,6 +16,17 @@ class Item(BaseModel):
     description: str | None = None
 
 
+class AliasedItem(BaseModel):
+    name: str = Field(serialization_alias="itemName")
+
+
+class AliasedItemWithDefaults(BaseModel):
+    name: str = Field(serialization_alias="itemName")
+    description: str | None = None
+    hidden: str = "secret"
+    status: str = "new"
+
+
 items = [
     Item(name="Plumbus", description="A multi-purpose household device."),
     Item(name="Portal Gun", description="A portal opening device."),
@@ -62,6 +73,65 @@ async def sse_items_event():
     yield ServerSentEvent(data="retry-test", retry=5000)
 
 
+@app.get("/items/stream-sse-event-model-data", response_class=EventSourceResponse)
+async def sse_items_event_model_data():
+    yield ServerSentEvent(data=AliasedItem(name="Portal Gun"))
+
+
+@app.get(
+    "/items/stream-sse-event-model-data-no-alias",
+    response_class=EventSourceResponse,
+    response_model_by_alias=False,
+)
+async def sse_items_event_model_data_no_alias():
+    yield ServerSentEvent(data=AliasedItem(name="Portal Gun"))
+
+
+@app.get(
+    "/items/stream-sse-event-model-data-include",
+    response_class=EventSourceResponse,
+    response_model_include={"name"},
+)
+async def sse_items_event_model_data_include():
+    yield ServerSentEvent(data=AliasedItemWithDefaults(name="Portal Gun"))
+
+
+@app.get(
+    "/items/stream-sse-event-model-data-exclude",
+    response_class=EventSourceResponse,
+    response_model_exclude={"hidden"},
+)
+async def sse_items_event_model_data_exclude():
+    yield ServerSentEvent(data=AliasedItemWithDefaults(name="Portal Gun"))
+
+
+@app.get(
+    "/items/stream-sse-event-model-data-exclude-none",
+    response_class=EventSourceResponse,
+    response_model_exclude_none=True,
+)
+async def sse_items_event_model_data_exclude_none():
+    yield ServerSentEvent(data=AliasedItemWithDefaults(name="Portal Gun"))
+
+
+@app.get(
+    "/items/stream-sse-event-model-data-exclude-unset",
+    response_class=EventSourceResponse,
+    response_model_exclude_unset=True,
+)
+async def sse_items_event_model_data_exclude_unset():
+    yield ServerSentEvent(data=AliasedItemWithDefaults(name="Portal Gun"))
+
+
+@app.get(
+    "/items/stream-sse-event-model-data-exclude-defaults",
+    response_class=EventSourceResponse,
+    response_model_exclude_defaults=True,
+)
+async def sse_items_event_model_data_exclude_defaults():
+    yield ServerSentEvent(data=AliasedItemWithDefaults(name="Portal Gun"))
+
+
 @app.get("/items/stream-mixed", response_class=EventSourceResponse)
 async def sse_items_mixed() -> AsyncIterable[Item]:
     yield items[0]
@@ -199,6 +269,55 @@ def test_sse_events_with_fields(client: TestClient):
     assert 'data: "retry-test"\n' in text
 
 
+def test_sse_event_model_data_uses_serialization_alias(client: TestClient):
+    response = client.get("/items/stream-sse-event-model-data")
+    assert response.status_code == 200
+    assert 'data: {"itemName":"Portal Gun"}\n' in response.text
+    assert '"name"' not in response.text
+
+
+def test_sse_event_model_data_respects_response_model_by_alias_false(
+    client: TestClient,
+):
+    response = client.get("/items/stream-sse-event-model-data-no-alias")
+    assert response.status_code == 200
+    assert 'data: {"name":"Portal Gun"}\n' in response.text
+    assert '"itemName"' not in response.text
+
+
+@pytest.mark.parametrize(
+    ("path", "expected_data"),
+    [
+        (
+            "/items/stream-sse-event-model-data-include",
+            '{"itemName":"Portal Gun"}',
+        ),
+        (
+            "/items/stream-sse-event-model-data-exclude",
+            '{"itemName":"Portal Gun","description":null,"status":"new"}',
+        ),
+        (
+            "/items/stream-sse-event-model-data-exclude-none",
+            '{"itemName":"Portal Gun","hidden":"secret","status":"new"}',
+        ),
+        (
+            "/items/stream-sse-event-model-data-exclude-unset",
+            '{"itemName":"Portal Gun"}',
+        ),
+        (
+            "/items/stream-sse-event-model-data-exclude-defaults",
+            '{"itemName":"Portal Gun"}',
+        ),
+    ],
+)
+def test_sse_event_model_data_respects_response_model_serialization_options(
+    client: TestClient, path: str, expected_data: str
+):
+    response = client.get(path)
+    assert response.status_code == 200
+    assert response.text == f"data: {expected_data}\n\n"
+
+
 def test_mixed_plain_and_sse_events(client: TestClient):
     response = client.get("/items/stream-mixed")
     assert response.status_code == 200