继续获取 CORS 策略：没有 'Access-Control-Allow-Origin' 即使使用 FastAPI CORSMiddleware
Keep getting CORS policy: No 'Access-Control-Allow-Origin' even with FastAPI CORSMiddleware
我正在开发一个具有快速API 后端和 React 前端的项目。通过 fetch 调用后端时，我有时会得到以下信息：
Access to fetch at 'http://localhost:8000/get-main-query-data' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
这种情况经常发生，我可以调用一个端点然后抛出错误。有时会为所有端点抛出错误
我已经在我的 main.py 中设置了 Middleware，就像这样：（也在这个 line）
# allows cross-origin requests from React
origins = [
"http://localhost",
"http://localhost:3000",
]
app.add_middleware(
CORSMiddleware,
allow_origins=origins,
allow_credentials=True,
allow_methods=["*"],
allow_headers=["*"],
)
这可能是 fetch it's self 的问题吗？我担心当我开始托管时会收到 CORS 错误并且我的原型将无法工作:(
整个main.py是这样的：
后端
""" API to allow for data retrieval and manipulation. """
from typing import Optional
from fastapi import FastAPI, HTTPException, status
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
import models
from db import Session
app = FastAPI()
""" Pydantic BaseModels for the API. """
class SignalJourneyAudiences(BaseModel):
"""SignalJourneyAudiences BaseModel."""
audienceId: Optional[int] # PK
segment: str
enabled: bool
class SignalJourneyAudienceConstraints(BaseModel):
"""SignalJourneyAudienceConstraints BaseModel."""
uid: Optional[int] # PK
constraintId: int
audienceId: int # FK - SignalJourneyAudiences -> audienceId
sourceId: int # FK - SignalJourneySources -> sourceId
constraintTypeId: int # FK - SignalJourneyConstraintType -> constraintTypeId
constraintValue: str
targeting: bool
frequency: int
period: int
class SignalJourneyAudienceConstraintRelations(BaseModel):
"""SignalJourneyAudienceConstraintRelations BaseModel."""
uid: Optional[int] # PK
audienceId: int
relation: str
constraintIds: str
class SignalJourneyConstraintType(BaseModel):
"""SignalJourneyConstraintType BaseModel."""
constraintTypeId: Optional[int] # PK
constraintType: str
class SingalJourneySources(BaseModel):
"""SignalJourneySources BaseModel."""
sourceId: Optional[int] # PK
source: str
# allows cross-origin requests from React
origins = [
"http://localhost",
"http://localhost:3000",
]
app.add_middleware(
CORSMiddleware,
allow_origins=origins,
allow_credentials=True,
allow_methods=["*"],
allow_headers=["*"],
)
# database instance
db = Session()
@app.get("/")
def index():
"""Root endpoint."""
return {
"messagee": "Welcome to Signal Journey API. Please use the API documentation to learn more."
}
@app.get("/audiences", status_code=status.HTTP_200_OK)
def get_audiences():
"""Get all audience data from the database."""
return db.query(models.SignalJourneyAudiences).all()
@app.get("/audience-constraints", status_code=status.HTTP_200_OK)
def get_audience_constraints():
"""Get all audience constraint data from the database."""
return db.query(models.SignalJourneyAudienceConstraints).all()
@app.get("/audience-constraints-relations", status_code=status.HTTP_200_OK)
def get_audience_constraints_relations():
"""Get all audience constraint data from the database."""
return db.query(models.SignalJourneyAudienceConstraintRelations).all()
@app.get("/get-constraint-types", status_code=status.HTTP_200_OK)
def get_constraints_type():
"""Get all audience constraint data from the database."""
return db.query(models.SignalJourneyConstraintType).all()
@app.post("/add-constraint-type", status_code=status.HTTP_200_OK)
def add_constraint_type(sjct: SignalJourneyConstraintType):
"""Add a constraint type to the database."""
constraint_type_query = (
db.query(models.SignalJourneyConstraintType)
.filter(
models.SignalJourneyConstraintType.constraintType
== sjct.constraintType.upper()
and models.SignalJourneyConstraintType.constraintTypeId
== sjct.constraintTypeId
)
.first()
)
if constraint_type_query is not None:
raise HTTPException(
status_code=status.HTTP_400_BAD_REQUEST,
detail="Constaint type already exists.",
)
constraint_type = models.SignalJourneyConstraintType(
constraintType=sjct.constraintType.upper(),
)
db.add(constraint_type)
db.commit()
return {
"message": f"Constraint type {sjct.constraintType.upper()} added successfully."
}
@app.get("/get-sources", status_code=status.HTTP_200_OK)
def get_sources():
"""Get all sources data from the database."""
return db.query(models.SingalJourneySources).all()
@app.post("/add-source", status_code=status.HTTP_200_OK)
def add_source_type(sjs: SingalJourneySources):
"""Add a new source type to the database."""
source_type_query = (
db.query(models.SingalJourneySources)
.filter(models.SingalJourneySources.source == sjs.source.upper())
.first()
)
if source_type_query is not None:
raise HTTPException(
status_code=status.HTTP_400_BAD_REQUEST,
detail="Source already exists.",
)
source_type = models.SingalJourneySources(source=sjs.source.upper())
db.add(source_type)
db.commit()
return {"message": f"Source {sjs.source.upper()} added successfully."}
"""
Endpoints for populating the UI with data. These need to consist of some joins.
Query to be used in SQL
SELECT
constraintid,
sja.segment,
sjs.source,
sjct.constrainttype,
constraintvalue,
targeting,
frequency,
period
FROM signaljourneyaudienceconstraints
JOIN signaljourneyaudiences sja ON sja.audienceid = signaljourneyaudienceconstraints.audienceid;
JOIN signaljourneysources sjs ON sjs.sourceid = signaljourneyaudienceconstraints.sourceid
JOIN signaljourneyconstrainttype sjct ON sjct.constrainttypeid = signaljourneyaudienceconstraints.constrainttypeid
"""
@app.get("/get-main-query-data", status_code=status.HTTP_200_OK)
def get_main_query_data():
"""Returns data for the main query."""
return (
db.query(
models.SignalJourneyAudienceConstraints.constraintId,
models.SignalJourneyAudiences.segment,
models.SingalJourneySources.source,
models.SignalJourneyConstraintType.constraintType,
models.SignalJourneyAudienceConstraints.constraintValue,
models.SignalJourneyAudienceConstraints.targeting,
models.SignalJourneyAudienceConstraints.frequency,
models.SignalJourneyAudienceConstraints.period,
)
.join(
models.SignalJourneyAudiences,
models.SignalJourneyAudiences.audienceId
== models.SignalJourneyAudienceConstraints.audienceId,
)
.join(
models.SingalJourneySources,
models.SingalJourneySources.sourceId
== models.SignalJourneyAudienceConstraints.sourceId,
)
.join(
models.SignalJourneyConstraintType,
models.SignalJourneyConstraintType.constraintTypeId
== models.SignalJourneyAudienceConstraints.constraintTypeId,
)
.all()
)
前端
我这样调用我的 API 端点：
//form.jsx
// pulls segments name from signaljourneyaudiences
useEffect(() => {
fetch('http://localhost:8000/audiences')
.then((res) => res.json())
.then((data) => setSegmentNames(data))
.catch((err) => console.log(err));
}, []);
// pulls field names from signaljourneyaudiences
useEffect(() => {
fetch('http://localhost:8000/get-constraint-types')
.then((res) => res.json())
.then((data) => setConstraints(data))
.catch((err) => console.log(err));
}, []);
// table.jsx
useEffect(() => {
fetch('http://localhost:8000/get-main-query-data')
.then((res) => res.json())
.then((data) => {
setTableData(data);
})
.catch((err) => console.log(err));
}, []);
正如您在此处看到的那样，table 已由端点填充，但另一方面，其中一个下拉列表没有。
HTTP 500 错误描述
INFO: 127.0.0.1:62301 - "GET /get-constraint-types HTTP/1.1" 500 Internal Server Error
2022-02-24 09:26:44,234 INFO sqlalchemy.engine.Engine [cached since 2972s ago] ()
ERROR: Exception in ASGI application
Traceback (most recent call last):
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1702, in _execute_context
context = constructor(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1013, in _init_compiled
self.cursor = self.create_cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1361, in create_cursor
return self.create_default_cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1364, in create_default_cursor
return self._dbapi_connection.cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 1083, in cursor
return self.dbapi_connection.cursor(*args, **kwargs)
sqlite3.ProgrammingError: SQLite objects created in a thread can only be used in that same thread. The object was created in thread id 6191820800 and this is thread id 6174994432.
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/uvicorn/protocols/http/httptools_impl.py", line 372, in run_asgi
result = await app(self.scope, self.receive, self.send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/uvicorn/middleware/proxy_headers.py", line 75, in __call__
return await self.app(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/applications.py", line 259, in __call__
await super().__call__(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/applications.py", line 112, in __call__
await self.middleware_stack(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/middleware/errors.py", line 181, in __call__
raise exc
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/middleware/errors.py", line 159, in __call__
await self.app(scope, receive, _send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/middleware/cors.py", line 92, in __call__
await self.simple_response(scope, receive, send, request_headers=headers)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/middleware/cors.py", line 147, in simple_response
await self.app(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/exceptions.py", line 82, in __call__
raise exc
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/exceptions.py", line 71, in __call__
await self.app(scope, receive, sender)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
raise e
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
await self.app(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/routing.py", line 656, in __call__
await route.handle(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/routing.py", line 259, in handle
await self.app(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/routing.py", line 61, in app
response = await func(request)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/routing.py", line 227, in app
raw_response = await run_endpoint_function(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/routing.py", line 162, in run_endpoint_function
return await run_in_threadpool(dependant.call, **values)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/concurrency.py", line 39, in run_in_threadpool
return await anyio.to_thread.run_sync(func, *args)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/anyio/to_thread.py", line 28, in run_sync
return await get_asynclib().run_sync_in_worker_thread(func, *args, cancellable=cancellable,
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/anyio/_backends/_asyncio.py", line 818, in run_sync_in_worker_thread
return await future
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/anyio/_backends/_asyncio.py", line 754, in run
result = context.run(func, *args)
File "/Users/paul/Developer/signal_journey/backend/./main.py", line 109, in get_constraints_type
return db.query(models.SignalJourneyConstraintType).all()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 2759, in all
return self._iter().all()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 2894, in _iter
result = self.session.execute(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/orm/session.py", line 1692, in execute
result = conn._execute_20(statement, params or {}, execution_options)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1614, in _execute_20
return meth(self, args_10style, kwargs_10style, execution_options)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/sql/elements.py", line 325, in _execute_on_connection
return connection._execute_clauseelement(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1481, in _execute_clauseelement
ret = self._execute_context(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1708, in _execute_context
self._handle_dbapi_exception(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 2026, in _handle_dbapi_exception
util.raise_(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/util/compat.py", line 207, in raise_
raise exception
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1702, in _execute_context
context = constructor(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1013, in _init_compiled
self.cursor = self.create_cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1361, in create_cursor
return self.create_default_cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1364, in create_default_cursor
return self._dbapi_connection.cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 1083, in cursor
return self.dbapi_connection.cursor(*args, **kwargs)
sqlalchemy.exc.ProgrammingError: (sqlite3.ProgrammingError) SQLite objects created in a thread can only be used in that same thread. The object was created in thread id 6191820800 and this is thread id 6174994432.
[SQL: SELECT "SignalJourneyConstraintType"."constraintTypeId" AS "SignalJourneyConstraintType_constraintTypeId", "SignalJourneyConstraintType"."constraintType" AS "SignalJourneyConstraintType_constraintType"
FROM "SignalJourneyConstraintType"]
[parameters: [{}]]
(Background on this error at: https://sqlalche.me/e/14/f405)
当发生服务器端错误（响应代码 5xx）时，CORS 中间件不会添加它们的 headers，因为请求已有效终止，使浏览器无法读取响应。
对于第二个问题，您应该为 API 的每次调用使用单独的 session。 The reference guide has an example of how to do this:
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
...
# Dependency
def get_db():
db = SessionLocal()
try:
yield db
finally:
db.close()
...
@app.post("/users/{user_id}/items/", response_model=schemas.Item)
def create_item_for_user(..., db: Session = Depends(get_db)):
return crud.create_user_item(db=db, item=item, user_id=user_id)
我正在开发一个具有快速API 后端和 React 前端的项目。通过 fetch 调用后端时，我有时会得到以下信息：
Access to fetch at 'http://localhost:8000/get-main-query-data' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
这种情况经常发生，我可以调用一个端点然后抛出错误。有时会为所有端点抛出错误
我已经在我的 main.py 中设置了 Middleware，就像这样：（也在这个 line）
# allows cross-origin requests from React
origins = [
"http://localhost",
"http://localhost:3000",
]
app.add_middleware(
CORSMiddleware,
allow_origins=origins,
allow_credentials=True,
allow_methods=["*"],
allow_headers=["*"],
)
这可能是 fetch it's self 的问题吗？我担心当我开始托管时会收到 CORS 错误并且我的原型将无法工作:(
整个main.py是这样的：
后端
""" API to allow for data retrieval and manipulation. """
from typing import Optional
from fastapi import FastAPI, HTTPException, status
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
import models
from db import Session
app = FastAPI()
""" Pydantic BaseModels for the API. """
class SignalJourneyAudiences(BaseModel):
"""SignalJourneyAudiences BaseModel."""
audienceId: Optional[int] # PK
segment: str
enabled: bool
class SignalJourneyAudienceConstraints(BaseModel):
"""SignalJourneyAudienceConstraints BaseModel."""
uid: Optional[int] # PK
constraintId: int
audienceId: int # FK - SignalJourneyAudiences -> audienceId
sourceId: int # FK - SignalJourneySources -> sourceId
constraintTypeId: int # FK - SignalJourneyConstraintType -> constraintTypeId
constraintValue: str
targeting: bool
frequency: int
period: int
class SignalJourneyAudienceConstraintRelations(BaseModel):
"""SignalJourneyAudienceConstraintRelations BaseModel."""
uid: Optional[int] # PK
audienceId: int
relation: str
constraintIds: str
class SignalJourneyConstraintType(BaseModel):
"""SignalJourneyConstraintType BaseModel."""
constraintTypeId: Optional[int] # PK
constraintType: str
class SingalJourneySources(BaseModel):
"""SignalJourneySources BaseModel."""
sourceId: Optional[int] # PK
source: str
# allows cross-origin requests from React
origins = [
"http://localhost",
"http://localhost:3000",
]
app.add_middleware(
CORSMiddleware,
allow_origins=origins,
allow_credentials=True,
allow_methods=["*"],
allow_headers=["*"],
)
# database instance
db = Session()
@app.get("/")
def index():
"""Root endpoint."""
return {
"messagee": "Welcome to Signal Journey API. Please use the API documentation to learn more."
}
@app.get("/audiences", status_code=status.HTTP_200_OK)
def get_audiences():
"""Get all audience data from the database."""
return db.query(models.SignalJourneyAudiences).all()
@app.get("/audience-constraints", status_code=status.HTTP_200_OK)
def get_audience_constraints():
"""Get all audience constraint data from the database."""
return db.query(models.SignalJourneyAudienceConstraints).all()
@app.get("/audience-constraints-relations", status_code=status.HTTP_200_OK)
def get_audience_constraints_relations():
"""Get all audience constraint data from the database."""
return db.query(models.SignalJourneyAudienceConstraintRelations).all()
@app.get("/get-constraint-types", status_code=status.HTTP_200_OK)
def get_constraints_type():
"""Get all audience constraint data from the database."""
return db.query(models.SignalJourneyConstraintType).all()
@app.post("/add-constraint-type", status_code=status.HTTP_200_OK)
def add_constraint_type(sjct: SignalJourneyConstraintType):
"""Add a constraint type to the database."""
constraint_type_query = (
db.query(models.SignalJourneyConstraintType)
.filter(
models.SignalJourneyConstraintType.constraintType
== sjct.constraintType.upper()
and models.SignalJourneyConstraintType.constraintTypeId
== sjct.constraintTypeId
)
.first()
)
if constraint_type_query is not None:
raise HTTPException(
status_code=status.HTTP_400_BAD_REQUEST,
detail="Constaint type already exists.",
)
constraint_type = models.SignalJourneyConstraintType(
constraintType=sjct.constraintType.upper(),
)
db.add(constraint_type)
db.commit()
return {
"message": f"Constraint type {sjct.constraintType.upper()} added successfully."
}
@app.get("/get-sources", status_code=status.HTTP_200_OK)
def get_sources():
"""Get all sources data from the database."""
return db.query(models.SingalJourneySources).all()
@app.post("/add-source", status_code=status.HTTP_200_OK)
def add_source_type(sjs: SingalJourneySources):
"""Add a new source type to the database."""
source_type_query = (
db.query(models.SingalJourneySources)
.filter(models.SingalJourneySources.source == sjs.source.upper())
.first()
)
if source_type_query is not None:
raise HTTPException(
status_code=status.HTTP_400_BAD_REQUEST,
detail="Source already exists.",
)
source_type = models.SingalJourneySources(source=sjs.source.upper())
db.add(source_type)
db.commit()
return {"message": f"Source {sjs.source.upper()} added successfully."}
"""
Endpoints for populating the UI with data. These need to consist of some joins.
Query to be used in SQL
SELECT
constraintid,
sja.segment,
sjs.source,
sjct.constrainttype,
constraintvalue,
targeting,
frequency,
period
FROM signaljourneyaudienceconstraints
JOIN signaljourneyaudiences sja ON sja.audienceid = signaljourneyaudienceconstraints.audienceid;
JOIN signaljourneysources sjs ON sjs.sourceid = signaljourneyaudienceconstraints.sourceid
JOIN signaljourneyconstrainttype sjct ON sjct.constrainttypeid = signaljourneyaudienceconstraints.constrainttypeid
"""
@app.get("/get-main-query-data", status_code=status.HTTP_200_OK)
def get_main_query_data():
"""Returns data for the main query."""
return (
db.query(
models.SignalJourneyAudienceConstraints.constraintId,
models.SignalJourneyAudiences.segment,
models.SingalJourneySources.source,
models.SignalJourneyConstraintType.constraintType,
models.SignalJourneyAudienceConstraints.constraintValue,
models.SignalJourneyAudienceConstraints.targeting,
models.SignalJourneyAudienceConstraints.frequency,
models.SignalJourneyAudienceConstraints.period,
)
.join(
models.SignalJourneyAudiences,
models.SignalJourneyAudiences.audienceId
== models.SignalJourneyAudienceConstraints.audienceId,
)
.join(
models.SingalJourneySources,
models.SingalJourneySources.sourceId
== models.SignalJourneyAudienceConstraints.sourceId,
)
.join(
models.SignalJourneyConstraintType,
models.SignalJourneyConstraintType.constraintTypeId
== models.SignalJourneyAudienceConstraints.constraintTypeId,
)
.all()
)
前端
我这样调用我的 API 端点：
//form.jsx
// pulls segments name from signaljourneyaudiences
useEffect(() => {
fetch('http://localhost:8000/audiences')
.then((res) => res.json())
.then((data) => setSegmentNames(data))
.catch((err) => console.log(err));
}, []);
// pulls field names from signaljourneyaudiences
useEffect(() => {
fetch('http://localhost:8000/get-constraint-types')
.then((res) => res.json())
.then((data) => setConstraints(data))
.catch((err) => console.log(err));
}, []);
// table.jsx
useEffect(() => {
fetch('http://localhost:8000/get-main-query-data')
.then((res) => res.json())
.then((data) => {
setTableData(data);
})
.catch((err) => console.log(err));
}, []);
正如您在此处看到的那样，table 已由端点填充，但另一方面，其中一个下拉列表没有。
HTTP 500 错误描述
INFO: 127.0.0.1:62301 - "GET /get-constraint-types HTTP/1.1" 500 Internal Server Error
2022-02-24 09:26:44,234 INFO sqlalchemy.engine.Engine [cached since 2972s ago] ()
ERROR: Exception in ASGI application
Traceback (most recent call last):
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1702, in _execute_context
context = constructor(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1013, in _init_compiled
self.cursor = self.create_cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1361, in create_cursor
return self.create_default_cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1364, in create_default_cursor
return self._dbapi_connection.cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 1083, in cursor
return self.dbapi_connection.cursor(*args, **kwargs)
sqlite3.ProgrammingError: SQLite objects created in a thread can only be used in that same thread. The object was created in thread id 6191820800 and this is thread id 6174994432.
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/uvicorn/protocols/http/httptools_impl.py", line 372, in run_asgi
result = await app(self.scope, self.receive, self.send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/uvicorn/middleware/proxy_headers.py", line 75, in __call__
return await self.app(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/applications.py", line 259, in __call__
await super().__call__(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/applications.py", line 112, in __call__
await self.middleware_stack(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/middleware/errors.py", line 181, in __call__
raise exc
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/middleware/errors.py", line 159, in __call__
await self.app(scope, receive, _send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/middleware/cors.py", line 92, in __call__
await self.simple_response(scope, receive, send, request_headers=headers)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/middleware/cors.py", line 147, in simple_response
await self.app(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/exceptions.py", line 82, in __call__
raise exc
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/exceptions.py", line 71, in __call__
await self.app(scope, receive, sender)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
raise e
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
await self.app(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/routing.py", line 656, in __call__
await route.handle(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/routing.py", line 259, in handle
await self.app(scope, receive, send)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/routing.py", line 61, in app
response = await func(request)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/routing.py", line 227, in app
raw_response = await run_endpoint_function(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/fastapi/routing.py", line 162, in run_endpoint_function
return await run_in_threadpool(dependant.call, **values)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/starlette/concurrency.py", line 39, in run_in_threadpool
return await anyio.to_thread.run_sync(func, *args)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/anyio/to_thread.py", line 28, in run_sync
return await get_asynclib().run_sync_in_worker_thread(func, *args, cancellable=cancellable,
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/anyio/_backends/_asyncio.py", line 818, in run_sync_in_worker_thread
return await future
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/anyio/_backends/_asyncio.py", line 754, in run
result = context.run(func, *args)
File "/Users/paul/Developer/signal_journey/backend/./main.py", line 109, in get_constraints_type
return db.query(models.SignalJourneyConstraintType).all()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 2759, in all
return self._iter().all()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 2894, in _iter
result = self.session.execute(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/orm/session.py", line 1692, in execute
result = conn._execute_20(statement, params or {}, execution_options)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1614, in _execute_20
return meth(self, args_10style, kwargs_10style, execution_options)
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/sql/elements.py", line 325, in _execute_on_connection
return connection._execute_clauseelement(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1481, in _execute_clauseelement
ret = self._execute_context(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1708, in _execute_context
self._handle_dbapi_exception(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 2026, in _handle_dbapi_exception
util.raise_(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/util/compat.py", line 207, in raise_
raise exception
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1702, in _execute_context
context = constructor(
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1013, in _init_compiled
self.cursor = self.create_cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1361, in create_cursor
return self.create_default_cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 1364, in create_default_cursor
return self._dbapi_connection.cursor()
File "/Users/paul/.local/share/virtualenvs/backend-CF5omcRU/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 1083, in cursor
return self.dbapi_connection.cursor(*args, **kwargs)
sqlalchemy.exc.ProgrammingError: (sqlite3.ProgrammingError) SQLite objects created in a thread can only be used in that same thread. The object was created in thread id 6191820800 and this is thread id 6174994432.
[SQL: SELECT "SignalJourneyConstraintType"."constraintTypeId" AS "SignalJourneyConstraintType_constraintTypeId", "SignalJourneyConstraintType"."constraintType" AS "SignalJourneyConstraintType_constraintType"
FROM "SignalJourneyConstraintType"]
[parameters: [{}]]
(Background on this error at: https://sqlalche.me/e/14/f405)
当发生服务器端错误（响应代码 5xx）时，CORS 中间件不会添加它们的 headers，因为请求已有效终止，使浏览器无法读取响应。
对于第二个问题，您应该为 API 的每次调用使用单独的 session。 The reference guide has an example of how to do this:
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
...
# Dependency
def get_db():
db = SessionLocal()
try:
yield db
finally:
db.close()
...
@app.post("/users/{user_id}/items/", response_model=schemas.Item)
def create_item_for_user(..., db: Session = Depends(get_db)):
return crud.create_user_item(db=db, item=item, user_id=user_id)