英文:
FastAPI: AssertionError
问题
当我尝试使用uvicorn启动API时，我遇到以下错误：
"AssertionError: Param: nodes can only be a request body, using Body():"
如何修复这个错误？
英文:
When i try to start the API with uvicorn, i get following error:
"""AssertionError: Param: nodes can only be a request body, using Body():"""
from fastapi import FastAPI
from fastapi.responses import JSONResponse
from typing import List, Dict
app = FastAPI(title="Neo4jAPI")
@app.post("/create_nodes/")
def post(nodes: List[Dict] | None = Header(default=None)):
#Some Logic
return JSONResponse(nodes)
How do i fix this error?
答案1
得分: 1
通过定义 nodes: ... = Header(default=None)，你告诉 FastAPI 应从请求头中提取 nodes 参数的值。
FastAPI 支持将头部作为单个值提取：例如，使用 user_agent: str = Header() 提取 User-Agent 头的值。
它还支持从头部提取值的列表，如果头部多次指定（参见 https://fastapi.tiangolo.com/lo/tutorial/header-params/）。
但是，它不支持从请求头中提取字典的列表。
你如何在请求头中建模这种情况？
你可能想要的是从请求体中提取节点（可能作为 JSON）。
修复这个问题的简单方法就是删除 = Header(...) 部分。如果只有一个参数，FastAPI 会假定它代表请求体。
@app.post("/create_nodes/")
def post(nodes: List[Dict] | None):
return JSONResponse(nodes)
英文:
By defining nodes: ... = Header(default=None), you tell FastAPI that the values of the nodes parameter should be extracted from the request headers.
FastAPI supports headers as single values: e.g. extracting the value of the User-Agent header with user_agent: str = Header().
It also supports extracting lists of values from headers, if headers are specified multiple times (see https://fastapi.tiangolo.com/lo/tutorial/header-params/).
However it doesn't support extracting lists of dictionaries from request headers.
How would you even model that in a request header?
What you probably want to do, is extract the nodes from the request body (probably as JSON).
The simple fix for it is just to remove the = Header(...) part. If there is just one parameter, FastAPI assumes that this represents the body.
@app.post("/create_nodes/")
def post(nodes: List[Dict] | None):
return JSONResponse(nodes)
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