FastAPI: how to read body as any valid json?

问题

Sorry, not proficient in Python.

I haven't found the docs for that use case. How can I get the request body, ensure its a valid Json (any valid json, including numbers, string, booleans and nulls, not only objects and arrays) and get the actual Json. Using pydantic forces the Json to have a specific structure.

回答1:

You can find nearly everything inside the Request object

You are able to get request body with request.body()

from fastapi import Request, FastAPI

@app.post("/dummypath")
async def get_body(request: Request):
    return await request.body()

回答2:

If you are confident that the incoming data is "a valid JSON", you can create a simple type annotation structure to receive the arbitrary JSON data.

from fastapi import FastAPI
from typing import Any, Dict, AnyStr, List, Union

app = FastAPI()

JSONObject = Dict[AnyStr, Any]
JSONArray = List[Any]
JSONStructure = Union[JSONArray, JSONObject]


@app.post("/")
async def root(arbitrary_json: JSONStructure = None):
    return {"received_data": arbitrary_json}

Examples

1. JSON object

curl -X POST "http://0.0.0.0:6022/" -H  "accept: application/json" -H  "Content-Type: application/json" -d "{\"test_key\":\"test_val\"}"

Response:

{
  "received_data": {
    "test_key": "test_val"
  }
}

2. JSON array

curl -X POST "http://0.0.0.0:6022/" -H  "accept: application/json" -H  "Content-Type: application/json" -d "[\"foo\",\"bar\"]"

Response:

{
  "received_data": [
    "foo",
    "bar"
  ]
}

If you are not sure about the content type of the incoming data, better to parse the request body.

It can be done as,

from fastapi import FastAPI, Request

app = FastAPI()


@app.post("/")
async def root(request: Request):
    return {"received_request_body": await request.body()}

The advantage of this method is that the body will contain any kind of data, JSON, form-data, multipart-form-data, etc.

回答3:

The accepted answer is valid as well, but FastAPI provides a built-in way to do that - check the Singular values in body section in docs.

A parameter with the default Body gets all the payload that doesn't match passed Pydantic-typed parameters (the whole payload in our case) and converts it to the dict. In case of invalid JSON, a standard validation error would be produced.

from fastapi import Body, FastAPI

app = FastAPI()


@app.post('/test')
async def update_item(
        payload: dict = Body(...)
):
    return payload

回答4:

from fastapi import Request

async def synonyms__select(request: Request):
    return await request.json()

will return a JSON object.

来源：https://stackoverflow.com/questions/64379089/fastapi-how-to-read-body-as-any-valid-json

标签

json

fastapi

pydantic