Merge 42a934ca17 into 6df50d40fe

docs/en/docs/tutorial/handling-errors.md

@@ -109,6 +109,37 @@ You could also use `from starlette.requests import Request` and `from starlette.
 
 ///
 
+### Handle multiple exceptions or status codes
+
+You can register the same handler for multiple exceptions or multiple status codes at once. Just pass a list or tuple of them to `@app.exception_handler(...)`.
+
+This is useful when you want to group related errors together and respond with the same logic.
+
+For example, if you want to treat 401 Unauthorized and 403 Forbidden as access-related issues:
+
+{* ../../docs_src/handling_errors/tutorial007.py hl[15:20,33,37] *}
+
+Raising an `HTTPException` with either a `401` or `403` status code will result in the same response detail:
+
+```JSON
+{"detail": "Access denied. Check your credentials or permissions."}
+```
+
+Or you can handle multiple exception classes like this:
+
+{* ../../docs_src/handling_errors/tutorial008.py hl[10:12,15:17,20:25,32,38] *}
+
+Here, if your request causes either a `FileTooLargeError` or an `UnsupportedFileTypeError`, the `custom_exception_handler` will be used to handle the exception and add a `hint` field to the response:
+
+```JSON
+{
+  "error": "The uploaded file is too large.",
+  "hint": "Need help? Contact support@example.com"
+}
+```
+
+This allows for simpler, more maintainable error handling when several conditions should result in the same kind of response.
+
 ## Override the default exception handlers
 
 **FastAPI** has some default exception handlers.

docs_src/handling_errors/tutorial007.py

@@ -0,0 +1,39 @@
+from typing import Union
+
+from fastapi import FastAPI, HTTPException, Request
+from fastapi.responses import JSONResponse
+
+app = FastAPI()
+
+FAKE_DB = {
+    0: {"name": "Admin", "role": "ADMIN"},
+    1: {"name": "User 1", "role": "USER"},
+    2: {"name": "User 2", "role": "USER"},
+}
+
+
+@app.exception_handler([401, 403])
+async def handle_auth_errors(request: Request, exc: Exception):
+    return JSONResponse(
+        status_code=exc.status_code if isinstance(exc, HTTPException) else 403,
+        content={"detail": "Access denied. Check your credentials or permissions."},
+    )
+
+
+@app.get("/secrets/")
+async def get_secrets(auth_user_id: Union[int, None] = None):
+    # Get authenticated user info (not a production-ready code)
+    if auth_user_id is not None:
+        auth_user_info = FAKE_DB.get(auth_user_id)
+    else:
+        auth_user_info = None
+
+    # Return 401 status code if user not authenticated
+    if auth_user_info is None:
+        raise HTTPException(status_code=401)  # Not authenticated
+
+    # Return 403 status code if user is not authorized to get secret information
+    if auth_user_info["role"] != "ADMIN":
+        raise HTTPException(status_code=403)  # Not authorized
+
+    return {"data": "Secret information"}

docs_src/handling_errors/tutorial008.py

@@ -0,0 +1,40 @@
+from fastapi import FastAPI, File, HTTPException, Request, UploadFile
+from fastapi.responses import JSONResponse
+
+MAX_FILE_SIZE_MB = 5
+ALLOWED_TYPES = {"application/pdf", "image/jpeg"}
+
+app = FastAPI()
+
+
+class FileTooLargeError(HTTPException):
+    def __init__(self):
+        super().__init__(status_code=413, detail="The uploaded file is too large.")
+
+
+class UnsupportedFileTypeError(HTTPException):
+    def __init__(self):
+        super().__init__(status_code=415, detail="Unsupported file type")
+
+
+@app.exception_handler((FileTooLargeError, UnsupportedFileTypeError))
+async def custom_exception_handler(request: Request, exc: HTTPException):
+    return JSONResponse(
+        status_code=exc.status_code,
+        content={"error": exc.detail, "hint": "Need help? Contact support@example.com"},
+    )
+
+
+@app.post("/upload/")
+async def upload_file(file: UploadFile = File(...)):
+    # Validate file type
+    if file.content_type not in ALLOWED_TYPES:
+        raise UnsupportedFileTypeError()
+
+    # Validate file size (read contents to check size in memory)
+    contents = await file.read()
+    size_mb = len(contents) / (1024 * 1024)
+    if size_mb > MAX_FILE_SIZE_MB:
+        raise FileTooLargeError()
+
+    return {"filename": file.filename, "message": "File uploaded successfully!"}

fastapi/applications.py

@@ -4543,10 +4543,10 @@ class FastAPI(Starlette):
     def exception_handler(
         self,
         exc_class_or_status_code: Annotated[
-            Union[int, Type[Exception]],
+            Union[int, Type[Exception], Sequence[int], Sequence[Type[Exception]]],
             Doc(
                 """
-                The Exception class this would handle, or a status code.
+                The Exception class, a status code or a sequence of them this would handle.
                 """
             ),
         ],
@@ -4582,7 +4582,11 @@ class FastAPI(Starlette):
         """
 
         def decorator(func: DecoratedCallable) -> DecoratedCallable:
-            self.add_exception_handler(exc_class_or_status_code, func)
+            if isinstance(exc_class_or_status_code, Sequence):
+                for exc_class_or_status_code_ in exc_class_or_status_code:
+                    self.add_exception_handler(exc_class_or_status_code_, func)
+            else:
+                self.add_exception_handler(exc_class_or_status_code, func)
             return func
 
         return decorator

tests/test_exception_handlers.py

@@ -5,6 +5,14 @@ from fastapi.testclient import TestClient
 from starlette.responses import JSONResponse
 
 
+class CustomException1(HTTPException):
+    pass
+
+
+class CustomException2(HTTPException):
+    pass
+
+
 def http_exception_handler(request, exception):
     return JSONResponse({"exception": "http-exception"})
 
@@ -86,3 +94,62 @@ def test_traceback_for_dependency_with_yield():
     last_frame = exc_info.traceback[-1]
     assert str(last_frame.path) == __file__
     assert last_frame.lineno == raise_value_error.__code__.co_firstlineno
+
+
+def test_exception_handler_with_single_exception():
+    local_app = FastAPI()
+
+    @local_app.exception_handler(CustomException1)
+    def custom_exception_handler(request, exception):
+        pass  # pragma: no cover
+
+    assert (
+        local_app.exception_handlers.get(CustomException1) == custom_exception_handler
+    )
+
+
+@pytest.mark.parametrize(
+    "exceptions",
+    [
+        (CustomException1, CustomException2),  # Tuple of exceptions
+        [CustomException1, CustomException2],  # List of exceptions
+    ],
+)
+def test_exception_handler_with_multiple_exceptions(exceptions):
+    local_app = FastAPI()
+
+    @local_app.exception_handler(exceptions)
+    def custom_exception_handler(request, exception):
+        pass  # pragma: no cover
+
+    assert local_app.exception_handlers.get(exceptions[0]) == custom_exception_handler
+
+    assert local_app.exception_handlers.get(exceptions[1]) == custom_exception_handler
+
+
+def test_exception_handler_with_single_status_code():
+    local_app = FastAPI()
+
+    @local_app.exception_handler(409)
+    def http_409_status_code_handler(request, exception):
+        pass  # pragma: no cover
+
+    assert local_app.exception_handlers.get(409) == http_409_status_code_handler
+
+
+@pytest.mark.parametrize(
+    "status_codes",
+    [
+        (401, 403),  # Tuple of status codes
+        [401, 403],  # List of status codes
+    ],
+)
+def test_exception_handler_with_multiple_status_codes(status_codes):
+    local_app = FastAPI()
+
+    @local_app.exception_handler(status_codes)
+    def auth_errors_handler(request, exception):
+        pass  # pragma: no cover
+
+    assert local_app.exception_handlers.get(status_codes[0]) == auth_errors_handler
+    assert local_app.exception_handlers.get(status_codes[1]) == auth_errors_handler

tests/test_tutorial/test_handling_errors/test_tutorial007.py

@@ -0,0 +1,27 @@
+from fastapi.testclient import TestClient
+
+from docs_src.handling_errors.tutorial007 import app
+
+client = TestClient(app)
+
+
+def test_unauthenticated():
+    response = client.get("/secrets")
+    assert response.status_code == 401, response.text
+    assert response.json() == {
+        "detail": "Access denied. Check your credentials or permissions."
+    }
+
+
+def test_unauthorized():
+    response = client.get("/secrets", params={"auth_user_id": 1})
+    assert response.status_code == 403, response.text
+    assert response.json() == {
+        "detail": "Access denied. Check your credentials or permissions."
+    }
+
+
+def test_success():
+    response = client.get("/secrets", params={"auth_user_id": 0})
+    assert response.status_code == 200, response.text
+    assert response.json() == {"data": "Secret information"}

tests/test_tutorial/test_handling_errors/test_tutorial008.py

@@ -0,0 +1,59 @@
+from pathlib import Path
+from unittest.mock import patch
+
+from fastapi.testclient import TestClient
+
+from docs_src.handling_errors import tutorial008
+from docs_src.handling_errors.tutorial008 import app
+
+client = TestClient(app)
+
+
+def test_unsupported_file_type(tmp_path: Path):
+    file = tmp_path / "test.txt"
+    file.write_text("<file content>")
+    with open(file, "+rb") as fp:
+        response = client.post(
+            "/upload",
+            files={"file": ("test.txt", fp, "text/plain")},
+        )
+    assert response.status_code == 415, response.text
+    assert response.json() == {
+        "error": "Unsupported file type",
+        "hint": "Need help? Contact support@example.com",
+    }
+
+
+def test_file_too_large(tmp_path: Path):
+    file = tmp_path / "test.pdf"
+    file.write_text("<file content>" * 100)  # ~1.37 kB
+    with patch.object(
+        tutorial008,
+        "MAX_FILE_SIZE_MB",
+        new=0.001,  # MAX_FILE_SIZE_MB = 1 kB
+    ):
+        with open(file, "+rb") as fp:
+            response = client.post(
+                "/upload",
+                files={"file": ("test.pdf", fp, "application/pdf")},
+            )
+    assert response.status_code == 413, response.text
+    assert response.json() == {
+        "error": "The uploaded file is too large.",
+        "hint": "Need help? Contact support@example.com",
+    }
+
+
+def test_success(tmp_path: Path):
+    file = tmp_path / "test.pdf"
+    file.write_text("<file content>")
+    with open(file, "+rb") as fp:
+        response = client.post(
+            "/upload",
+            files={"file": ("test.pdf", fp, "application/pdf")},
+        )
+    assert response.status_code == 200, response.text
+    assert response.json() == {
+        "filename": "test.pdf",
+        "message": "File uploaded successfully!",
+    }